Chapter 40: Glenohumeral Instability

Andrew Jawa, Eric T. Ricchetti

Chapter Outline

Background on Glenohumeral Instability

Definition of Glenohumeral Instability

Glenohumeral instability is defined as the symptomatic and pathologic condition in which the humeral head does not remain centered in the glenoid fossa. Although the definition is simple, it includes a wide spectrum of diseases which has become larger with more nuances as our understanding of the pathoanatomy and clinical presentation evolves. 
Importantly, instability is not the same as laxity, which is a physical examination finding that is a property of normal joints. Laxity is defined as the degree to which the humeral head passively translates, relative to the glenoid, with the application of a load. By definition, it is asymptomatic. It varies with age, gender, and congenital factors.74,248,347 In addition, there is a wide spectrum of laxity among normal individuals.119,118 Hyperlaxity may contribute to instability, but the two are separate concepts.248 

Classification of Glenohumeral Instability

A number of classification systems have been developed to define glenohumeral instability, but with a rapidly evolving understanding of the pathology, many are incomplete and none are universal. As such, a descriptive classification of instability has become the standard rather than one based on reproducibility and high intra- and interobserver reliability. 

Descriptive Classification

Glenohumeral instability is currently defined by six characteristics: Severity (subluxation vs. dislocation), etiology (traumatic, microtraumtic, atraumatic, neuromuscular), chronicity (acute vs. chronic), frequency (initial vs. recurrent), volition (voluntary vs. involuntary), and direction (anterior, posterior, inferior, superior, bidirectional, multidirectional (MDI)). Each of these terms can be used in a description of a patient’s instability episode. For example, an instability event may be described as a recurrent, acute, traumatic, involuntary, anterior dislocation of the glenohumeral joint (Table 40-1). 
 
Table 40-1
Descriptive Classification of Shoulder Instability
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Table 40-1
Descriptive Classification of Shoulder Instability
Severity Volition
Subluxation Voluntary
Dislocation Involuntary
Etiology Direction
Traumatic Anterior
Microtraumatic Posterior
Atraumatic Inferior
Neuromuscular Superior
Chronicity Bidirectional
Acute Multidirectional
Chronic
Frequency
Initial
Recurrent
X
Severity.
A dislocation is defined as a complete symptomatic dissociation of the articular surfaces of the humeral head and glenoid without spontaneous reduction. The need for a manual reduction (or a confirmatory radiograph) is required to define a dislocation. A subluxation is a symptomatic dissociation of the articular surfaces with spontaneous reduction. The degree or dissociation varies and includes complete separation.256 
Symptomology is the key feature for both. The symptom felt is typically apprehension, the feeling of the humeral head translating out of the glenoid fossa. Pain may also be a symptom, but, without apprehension, other diagnoses should be considered. 
Etiology.
There are currently four defined etiologies of instability: Traumatic, neuromuscular, atraumatic, and microtraumatic. Traumatic causes include injuries such as falls or motor vehicle accidents in which a large external force is the major contributor to the instability. This etiology should be distinguished from neuromuscular causes like seizures and strokes in which the imbalance of the glenohumeral muscular stabilizers leads to instability. Atraumatic instability, by definition, is not associated with a single traumatic episode. Microtraumatic instability is a controversial theoretical category in which repetitive symptomatic and asymptomatic microtrauma lead to chronic joint changes and subsequent instability. Microtraumatic instability is sometimes called acquired instability. As discussed later, atraumatic or microtraumatic instability is often associated with posterior, bidirectional, and multidirectional instability and underlying hyperlaxity. Congenital predisposition to instability may be related to glenoid dysplasia, or systemic syndromes like Ehlers–Danlos. Often these patients have atraumatic or microtraumatic instability. 
Frequency and Chronicity.
The frequency of instability is defined as either an initial or recurrent episode. The event may be either a subluxation or a dislocation. The chronicity of instability is a spectrum with no clear definition for what defines acute versus chronic. Typically the terms are used to describe a dislocation (vs. subluxation). As such, acute is best defined as a time from the episode to presentation in which a closed reduction is likely to succeed (3 to 6 weeks).56,126,311 Chronic dislocations are typically locked or fixed, meaning the humeral head is impaled on the edge of the glenoid making reduction difficult (Fig. 40-1). The terms locked, chronic, and fixed have sometimes been used interchangeably and the exact definition can be confusing.126,311 As such, it is best to define the timeframe as well as the humeral head pathology. 
Note the position of the humeral head directly below the acromion.
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Figure 40-1
Axillary view of a chronic subacromial posterior dislocation with the humeral head “locked” or “fixed” on the posterior glenoid.
Note the position of the humeral head directly below the acromion.
Note the position of the humeral head directly below the acromion.
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Volition.
Voluntary instability, in which the patient can dislocate at will, is often atraumatic and can be associated with psychiatric problems or secondary gain. Rowe designated these patients “habitual dislocators.”233,308 This group should be distinguished from patients who have no underlying psychological issues, but who have learned the position(s) of instability. They can reproduce their instability, but are symptomatic and try to avoid these positions. These patients seek medical advice because they typically have an involuntary component that they cannot control. Last, there is a rare group of patients who can dissociate their humeral head and glenoid at will, but are neither symptomatic nor desire secondary gain. By definition, they do not have instability because they have exceptional control over their glenohumeral joint.97 

Direction

The directions of instability have increased with the growing recognition of patient pathology and presentation. Anterior, posterior, superior, inferior, and multi- or bidirectional25 instability have all been described. Confusion certainly exists in defining the direction of instability because there can be overlap or misdiagnosis. 
Anterior unidirectional instability is, by far, the most common.183,254 There are a number of named types of anterior dislocations that likely represent a spectrum of direction. Nonetheless, they have been described and need to be mentioned though there are few implications for treatment. The typical anterior dislocation, representing about two-thirds of anterior dislocations, is called a subcoracoid dislocation as the humeral head is located below the coracoid process (Fig. 40-2).49 Subglenoid dislocations, in which the humeral head is inferior to the glenoid, represents about one-third of dislocations (Fig. 40-3). Often this type of dislocation is associated with a greater tuberosity fracture.49 The remaining two types, subclavicular, in which the humeral head is medial to the glenoid and inferior to clavicle, and intrathoracic, in which the humeral head lies within the thorax, are very uncommon.49,71,361 
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Figure 40-2
AP view of a subcoracoid dislocation.
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Figure 40-3
AP view of a subglenoid dislocation.
 
Note the associated greater tuberosity fracture.
Note the associated greater tuberosity fracture.
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Figure 40-3
AP view of a subglenoid dislocation.
Note the associated greater tuberosity fracture.
Note the associated greater tuberosity fracture.
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Posterior instability, as discussed later in the epidemiology section, represents less than 10% of instability. Several types of dislocations have been named, but the terminology is uncommonly used as it has little or no implication for treatment. The terms subacromial (most common), subspinous, and subglenoid have all been used to describe the position of the posterior dislocation, though the exact definitions are not clear (Fig. 40-1). Posterior subluxation, however, is more common than frank dislocation and commonly associated with an inferior component—making the instability bi- or multidirectional.25 
A directly inferior dislocation is also known as luxatio erecta (Fig. 40-4). This is an uncommon traumatic injury in which the humeral head is directly inferior to the glenoid and the humerus is locked in 100 to 160 degrees of abduction.81,86,109,206 More typically, inferior instability is an atraumatic subluxation associated with a posterior or MDI component (Fig. 40-5).233 
Figure 40-4
Locked inferior dislocation of the glenohumeral joint, also known as luxatio erecta.
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Figure 40-5
Inferior subluxation of the humeral head seen in a patient with atraumatic multidirectional instability.
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Superior dislocations are extremely high-energy injuries that have only been described in case reports.69 This type should be distinguished from superior humeral head migration associated with chronic rotator cuff arthropathy (Fig. 40-6). 
Figure 40-6
Superior migration of the humeral head associated with a chronic massive rotator cuff tear.
 
This superior displacement should be distinguished from a superior dislocation which is caused by a rare, acute, high-energy injury mechanism.
This superior displacement should be distinguished from a superior dislocation which is caused by a rare, acute, high-energy injury mechanism.
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Figure 40-6
Superior migration of the humeral head associated with a chronic massive rotator cuff tear.
This superior displacement should be distinguished from a superior dislocation which is caused by a rare, acute, high-energy injury mechanism.
This superior displacement should be distinguished from a superior dislocation which is caused by a rare, acute, high-energy injury mechanism.
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MDI is inconsistently defined in the literature.212 We use the simplest definition: Instability in two or more directions. Some authors do distinguish between bidirectional instability (typically anteroinferior or posteroinferior)25 and global MDI instability as management can be affected. 

Common Patterns of Instability

Because the six criteria create a large number of permutations in the classification of instability, we discuss below the most common patterns seen clinically. The epidemiology, pathoanatomy, and clinical presentation are expanded upon later in the text.233 
Traumatic Anterior Dislocation.
The typical patient is a young male less than 30 years of age. This pattern is also seen in older patients, but with a higher incidence of associated injuries (especially rotator cuff injuries).236 The pathoanatomy is often a capsule-labral avulsion (Bankart lesion), but others are described in detail below. Recurrence is most common in the younger population and often requires surgery.299 
Recurrent Anterior Subluxation.
This pattern is uncommon, but is also under-recognized. It has been described in the high-level athlete or military population. Repetitive stresses such as pitching, stretching the static stabilizers (e.g., capsule), and fatigue of the dynamic stabilizers (e.g., rotator cuff) precipitates apprehension or pain.310 
Acute and Chronic Traumatic Posterior Dislocation.
Posterior dislocations are uncommon and are seen in high-energy motor vehicle accidents, seizures (especially during alcohol withdrawal), or electric shock. Acute dislocations have been reported to be missed up to 50% of the time126,215 and hence become chronic. 
Recurrent Posterior Subluxation
Acquired Recurrent Posterior Subluxation.
This is the most common form of recurrent posterior subluxation. Patients may have a completely atraumatic form, acquire the instability through macrotrauma with a definable causative event, or acquire instability by repetitive microtrauma that leads to deformation of the static stabilizers (e.g., capsule) over time. There is an overlap with inferior instability and even ultimately with MDI.25,89 These patients also respond well to rehabilitation. 
Volitional Recurrent Posterior Subluxation.
Voluntary recurrent instability comes in two forms: Habitual dislocaters (those who dislocate or subluxate for secondary gain and psychological need)308 and patients without psychiatric issues, but who are able to recreate their position of instability. In both groups, these patients can selectively inhibit certain muscle groups to create posterior instability.259 However, in the latter, the patients also have a symptomatic involuntary component that they cannot control. These patients respond well to therapy. The habitual dislocaters do poorly with all treatment. 
Dysplastic Recurrent Posterior Subluxation.
Congenital causes such as localized posterior glenoid hypoplasia72 or increased retroversion can lead to recurrent instability, but these conditions are rare (Fig. 40-7). These abnormalities do not necessitate instability, but may predispose patients to it.95 
Note the posterior subluxation of the humeral head.
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Figure 40-7
Posterior glenoid hypoplasia seen on a CT scan in a patient with recurrent posterior instability.
Note the posterior subluxation of the humeral head.
Note the posterior subluxation of the humeral head.
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Multidirectional Instability.
MDI is not fully understood, but is simply defined as involuntary instability (dislocation or subluxation) in two or more directions. However, the inconsistency in the literature of the characteristic findings makes a more specific definition difficult.212 The etiology is either atraumatic or acquired with repetitive microtrauma. Altered proprioception and scapular dyskinesis have also been associated with MDI. Importantly, there is sometimes confusion between hyperlaxity and instability leading to misdiagnosis. Patients with instability are symptomatic, and patients with hyperlaxity may be predisposed to instability97,248 MDI patients often do well with rehabilitation, but can be successfully treated with a capsular shift if nonoperative measures fail. 

Other Classifications

Orthopaedic Trauma Association.
The Orthopaedic Trauma Association (OTA) in their 2007 Fracture and Dislocation Compendium included a classification for shoulder dislocations.208 In this system, the shoulder region is “10.” The first digit (“1”) specifies the shoulder girdle whereas the second digit (“0”) specifies dislocation. A letter is used to identify the specific joint (A, glenohumeral; B, sternoclavicular; C, acromioclavicular; D, scapulothoracic), followed by another number to describe the direction (1, anterior; 2, posterior; 3, lateral (theoretical); 4, medial (theoretical); 5, other (inferior-luxatio erecta)). 
For example, an anterior glenohumeral dislocation would be classified as “10-A1.” The system is excellent for defining an acute event and for recording it in a database. However, the system is not comprehensive enough to define other key factors in treatment including severity (subluxation vs. dislocation), etiology (traumatic vs. atraumatic/acquired vs. neuromuscular), chronicity (acute vs. chronic), frequency (initial vs. recurrent), and volition (voluntary vs. involuntary). 

Epidemiology of Glenohumeral Instability

The glenohumeral joint is the most commonly dislocated joint in the body representing 45% of all dislocations.164 Reported instability rates range from 11.2 to 23.9/100,000 person-years241,324,374 and likely underestimate the true incidence as the data is defined by patients seeking medical attention. The data does not include patients with self-reduced dislocations or subluxations who did not present to emergency departments. 
The best and most current data comes from the study by Zacchilli and Owens in 2010 finding an incidence of 23.9/100,000 person-years in patients presenting to emergency departments in the United States.374 A total of 8,940 dislocations were seen over a 4-year period between 2002 and 2006. Men, compared to women, had an incidence rate ratio of 2.64, with 71.8% of dislocations occurring in men. There was no difference based on race. The peak incidence of dislocation (47.8/100,000 person-years) occurred between ages 20 and 29 years with 46.8% of all dislocations occurring in patients between 15 and 29 years of age. There is a bimodal distribution, however, with a second peak incidence rate between 80 and 89 years of age. Most dislocations (58.8%) occurred during a fall, whereas 48.3% occurred during sports activities (Fig. 40-8). Importantly, this data did not exclude recurrent dislocations.374 
Figure 40-8
 
Total weighted NEISS estimates of all shoulder dislocations in the United States between 2002 and 2006 by age and sex, demonstrating a bimodal distribution with peaks among males between the ages of 20 and 29 years and females between the ages of 80 and 89 years. p-y, person-years. The vertical bars denote the 95% confidence interval. (From Zacchilli MA, Owens BD. Epidemiology of shoulder dislocations presenting to emergency departments in the United States. J Bone Joint Surg Am. 2010;92(3):542–549).
Total weighted NEISS estimates of all shoulder dislocations in the United States between 2002 and 2006 by age and sex, demonstrating a bimodal distribution with peaks among males between the ages of 20 and 29 years and females between the ages of 80 and 89 years. p-y, person-years. The vertical bars denote the 95% confidence interval. (From Zacchilli MA, Owens BD. Epidemiology of shoulder dislocations presenting to emergency departments in the United States. J Bone Joint Surg Am. 2010;92(3):542–549).
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Figure 40-8
Total weighted NEISS estimates of all shoulder dislocations in the United States between 2002 and 2006 by age and sex, demonstrating a bimodal distribution with peaks among males between the ages of 20 and 29 years and females between the ages of 80 and 89 years. p-y, person-years. The vertical bars denote the 95% confidence interval. (From Zacchilli MA, Owens BD. Epidemiology of shoulder dislocations presenting to emergency departments in the United States. J Bone Joint Surg Am. 2010;92(3):542–549).
Total weighted NEISS estimates of all shoulder dislocations in the United States between 2002 and 2006 by age and sex, demonstrating a bimodal distribution with peaks among males between the ages of 20 and 29 years and females between the ages of 80 and 89 years. p-y, person-years. The vertical bars denote the 95% confidence interval. (From Zacchilli MA, Owens BD. Epidemiology of shoulder dislocations presenting to emergency departments in the United States. J Bone Joint Surg Am. 2010;92(3):542–549).
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The risk of recurrent anterior instability is highest among young male patients.132,306 The reported rates have varied considerably in the literature from 30%323 to 90%272 mainly because of lack of follow-up and the retrospective nature of most studies. Robinson et al.299 in their prospective observational cohort study found patients between 15 and 35 years of age developed recurrent instability in 55.7% of shoulders within the first 2 years after dislocation. The rate increased to 66.8% by the fifth year. As previous reports documented, young males were at greatest risk for recurrent anterior instability (Table 40-2). In addition, Marans et al. reported in 21 patients with open physes that the risk of recurrent instability was 100% regardless of gender.205 
Table 40-2
Age and Sex-Specific Estimated Probability of Recurrent Instability within the First 2 Years After a Primary Glenohumeral Dislocation
Age (yrs) Males Females
15 0.86 0.54
16 0.84 0.51
17 0.81 0.48
18 0.78 0.45
19 0.75 0.42
20 0.72 0.40
21 0.69 0.37
22 0.66 0.34
23 0.62 0.32
24 0.59 0.30
25 0.56 0.28
26 0.53 0.26
27 0.50 0.24
28 0.47 0.22
29 0.43 0.20
30 0.41 0.19
31 0.39 0.17
32 0.36 0.16
33 0.34 0.15
34 0.31 0.14
35 0.29 0.13
 

Reproduced from Robinson CM, Howes J, Murdoch H, et al. Functional outcome and risk of recurrent instability after primary traumatic anterior shoulder dislocation in young patients. J Bone Joint Surg Am. 2006;88(11):2326–3336.

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There is a paucity of epidemiologic work for posterior instability. Robinson et al. performed the best retrospective review of traumatic posterior dislocations301 finding a prevalence of 1.1/100,000 patient years or 5% of all dislocations.374 Like anterior dislocations, there is a bimodal distribution with peaks in male patients between 20 and 49 years of age and over 70 years of age. Up to 70% are caused by a traumatic accident with the remainder caused by seizures. Recurrent instability is seen in 18% of shoulders in the first year with risk factors including seizure etiology, a large humeral head defect, and age less than forty. 
Little is known about the epidemiology of subluxations (anterior, posterior, or MDI) in the general population as most patients do not present for medical attention. However, some of this data has been captured in the military population, which is intrinsically younger and more active than the general population. Over a 10-month period, all new traumatic shoulder instability events in the United States Military Academy were evaluated.254 Among 4,141 students, 117 experienced new traumatic shoulder instability events with 11 experiencing multiple events. Interestingly, only 18 events were dislocations (15.4%) whereas 99 were subluxations (84.6%). Of the 99 subluxations, 45 (45.5%) were primary events, whereas 54 (54.5%) were recurrent. The majority of the 117 events were anterior (80.3%), whereas 12 (10.3%) were posterior, and 11 (9.4%) were MDI. Contact and noncontact injuries were responsible for 44(41%) of the instability events, respectively. Data was unavailable for the remaining 15%. We are unaware of any other literature reliably examining the epidemiology of MDI. 
The direction of dislocation was only recorded in one of the six primary epidemiologic studies183,241,253,254,324,374 on shoulder instability and therefore, our current understanding is limited. In their study of 216 dislocations, Kroner et al. found anterior and posterior dislocations (subluxations were not recorded) to represent 97.2 and 2.8% of events, respectively.183 No inferior dislocations were noted. 

Anatomy and Pathoanatomy Relating to Glenohumeral Instability

Anatomy of Glenohumeral Stability

Joint stability is maintained by both static and dynamic elements. The static stabilizers include the bony anatomy, the glenoid labrum, negative intra-articular pressure, adhesion–cohesion, capsuloligamentous structures, and the rotator cuff. The dynamic stabilizers include the rotator cuff muscles, the biceps tendon, the deltoid, scapular motion, and proprioception. 
Static Constraints
Bone.
The glenoid face is pear-shaped with the inferior two-thirds roughly a circle (Fig. 40-9).141 The average width and height are 24 and 35 mm, respectively.55 The glenoid covers only a maximum of 25% to 30% of the humeral head315 and therefore the glenohumeral joint has limited intrinsic bony stability. This stability is enhanced by a slight concavity of the glenoid—both through a slightly conforming bony anatomy and the thinning of the cartilage in the center of the glenoid (“the bare area”).353 However, because mobility is critical to the shoulder joint, the radius of curvature of the glenoid surface is greater (less curved) than the humeral head by 2.3 mm to prevent impingement of the head at the periphery of the glenoid.142 
Figure 40-9
The glenoid face is pear shaped with the inferior two-thirds roughly a circle.
 
The diameter of the red circle is exactly two-thirds the blue line, the height of the glenoid.
The diameter of the red circle is exactly two-thirds the blue line, the height of the glenoid.
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Figure 40-9
The glenoid face is pear shaped with the inferior two-thirds roughly a circle.
The diameter of the red circle is exactly two-thirds the blue line, the height of the glenoid.
The diameter of the red circle is exactly two-thirds the blue line, the height of the glenoid.
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The glenoid also has a slight (5 to 10 degrees) superior inclination relative to the vertical axis of the scapular body.17,314 This inclination may play a role in preventing inferior instability of the glenohumeral joint as patients with MDI are more likely to have a downward facing glenoid.17 
Labrum.
The labrum is a wedge-shaped dense fibrous structure of packed collagen fibers circumferentially surrounding the glenoid. Its purpose is to deepen the glenoid fossa and to create more surface area.344 Anatomically, the labrum and cartilage together effectively deepen the glenoid by 80% helping to prevent the head from rolling over the glenoid edge.190 In addition, the labrum indirectly confers stability by allowing for the attachment of the glenohumeral ligaments as discussed below (Fig. 40-10).58 
Figure 40-10
 
A: Cross-sectional anatomy of a normal shoulder. Note the close relationship between the subscapularis tendon and the anterior capsule. B: A magnified view of the anterior joint is essentially devoid of fibrocartilage and is composed of tissues from nearby hyaline cartilage, capsule, synovium, and periosteum.
A: Cross-sectional anatomy of a normal shoulder. Note the close relationship between the subscapularis tendon and the anterior capsule. B: A magnified view of the anterior joint is essentially devoid of fibrocartilage and is composed of tissues from nearby hyaline cartilage, capsule, synovium, and periosteum.
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Figure 40-10
A: Cross-sectional anatomy of a normal shoulder. Note the close relationship between the subscapularis tendon and the anterior capsule. B: A magnified view of the anterior joint is essentially devoid of fibrocartilage and is composed of tissues from nearby hyaline cartilage, capsule, synovium, and periosteum.
A: Cross-sectional anatomy of a normal shoulder. Note the close relationship between the subscapularis tendon and the anterior capsule. B: A magnified view of the anterior joint is essentially devoid of fibrocartilage and is composed of tissues from nearby hyaline cartilage, capsule, synovium, and periosteum.
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It is important to note that recent studies demonstrated that if the labrum could be removed with the ligament attachment sites maintained, glenohumeral stability in the midrange of motion decreased, but was unaltered at the end-range290 when the capsuloligamentous structures were taut.190 In other words, an isolated labral lesion (without capsular injury) is not sufficient to cause gross instability, but can lead to a nonconcentric humeral head position. 
Intra-Articular Pressure.
The osmotic action of the synovium to remove fluid creates a negative intra-articular pressure in the joint.195 When the capsule is vented with an 18-gauge needle, the force necessary to translate the humeral head decreases by almost 50%, particularly in the inferior direction.99 Traumatic capsular tears or an enlarged rotator interval, sometimes seen after a dislocation, may result in decreased pressure and increased instability.114 
Adhesion–Cohesion.
The glenohumeral joint normally only contains 1 cc of synovial fluid that nourishes the articular surface. This fluid also provides a minor stabilizing mechanism through adhesion–cohesion. Through intermolecular forces, the fluid allows for the sliding of cartilage surfaces and confers a static restraint to separation.143,145 The clinical effect, like intra-articular pressure, is small. 
Capsule and Ligament.
The capsuloligamentous structures are the primary static stabilizers of the glenohumeral joint. However, unlike in the elbow or knee where the ligaments are isometric during motion, the ligaments and capsule in the shoulder are generally lax and only provide stability at the extremes of motion under tension.118 The normal glenohumeral joint capsule is loose and redundant to allow for range of motion. Depending on the position of the shoulder, certain capsuloligamentous structures will tighten and act as a restraint against humeral head translation.252 These glenohumeral ligaments are expanded upon below (Fig. 40-11). 
Figure 40-11
The capsuloligamentous anatomy of the glenohumeral joint.
 
(From Iannotti JP. Disorders of the Shoulder: Diagnosis and Management. 2nd ed. Lippincott Williams and Wilkins; 2006 with permission.)
(From Iannotti JP. Disorders of the Shoulder: Diagnosis and Management. 2nd ed. Lippincott Williams and Wilkins; 2006 with permission.)
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Figure 40-11
The capsuloligamentous anatomy of the glenohumeral joint.
(From Iannotti JP. Disorders of the Shoulder: Diagnosis and Management. 2nd ed. Lippincott Williams and Wilkins; 2006 with permission.)
(From Iannotti JP. Disorders of the Shoulder: Diagnosis and Management. 2nd ed. Lippincott Williams and Wilkins; 2006 with permission.)
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The Superior Glenohumeral Ligament.
The superior glenohumeral ligament (SGHL) originates from the anterior superior aspect of the glenoid (anterior and inferior to the biceps origin) and extends to the anterior aspect of the humeral head to the superior edge of the lesser tuberosity. It crosses over the capsule of the rotator interval between the supraspinatus and the subscapularis and lies deep to the coracohumeral ligament (CHL). It is the most consistent of all the glenohumeral ligaments and is present in over 90% of shoulders.246 
Some biomechanical studies differ in explaining the primary and secondary roles of the ligament.246 The SGHL, however, clearly limits inferior humeral head translation and external rotation in the adducted arm.17 In addition, it limits posterior humeral head translation with the arm in forward flexion, adduction, and internal rotation17,354 Basmajian further makes the point that the SGHL works in conjunction with the superior tilt of the glenoid to provide passive restraint to inferior humeral head translation.17 
The Middle Glenohumeral Ligament.
The middle glenohumeral ligament (MGHL) is less consistent than the SGHL with variable origins.77 It can arise from the supraglenoid tubercle, anterosuperior aspect of the labrum, or the scapular neck and insert variably on the anterior humeral head medial and inferior to the lesser tuberosity. In up to one-third of shoulders it may be absent or significantly attenuated, potentially contributing to anterior instability.77 The MGHL is maximally taut in external rotation and about 45 degrees of abduction,346 functioning as a primary stabilizer of anterior translation and a secondary stabilizer to external rotation in abduction. It may also act as a secondary stabilizer to inferior translation in adduction.354 In abduction, beyond 45 degrees, the role of the IGHL becomes more important. 
The Inferior Glenohumeral Ligament Complex.
The inferior glenohumeral ligament complex (IGHLC) consists of three different components: The anterior band, the axillary pouch, and the posterior band, with the anterior band the thickest at 2.8 mm.243 The ligament originates from the anteroinferior–posteroinferior labrum and extends to the inferior aspect of the lesser tuberosity and around the anatomic neck of the humerus. It is intimately associated with the joint capsule.245 Compared to the MGHL, the anterior part of the IGHLC is tensioned in further abduction and external rotation and in this position has been demonstrated to be the primary stabilizer against anterior and inferior translation of the humeral head.244 In addition, in 90 degrees of abduction and internal rotation, the posterior band along with the capsule is the primary stabilizer to posterior translation.243 In adduction, the IGHLC is a secondary stabilizer to inferior translation.354 The IGHLC is the most important ligament clinically. 
The Coracohumeral Ligament and The Rotator Interval.
In contrast to the glenohumeral ligaments, the coracohumeral ligament originates from outside the joint. It arises from the lateral aspect of the coracoid process, passes within the interval between the subscapularis and the supraspinatus tendons blending with the capsule, and attaching in two bands to the lesser and greater tuberosities, respectively.161 The CHL is a constant structure. Together with the SGHL, the CHL and the capsule collectively form the roof of the rotator interval. The CHL plays the same role as the SGHL,120,161 limiting external rotation and inferior translation when the arm is adducted. It is also a secondary stabilizer to posterior instability.120 
The Coracoacromial Ligament.
The coracoacromial ligament connects two points of the scapula, originating from the lateral aspect of the coracoid and attaching to the anterior portion of the acromion. Though, at rest, it does not directly restrain the humeral head, its resection increases anterior humeral translation in slight abduction and implies a stabilizing effect to the joint.328,329 In addition, the ligament is a constraint to superior escape of the humeral head in the setting of massive rotator cuff tears.116 
The Posterior Capsule.
The capsule extending from the posterior band of the IGHLC to the biceps insertion is termed the posterior capsule. It is extremely thin and does not have additional ligamentous support.243 It helps to limit posterior translation when the shoulder is flexed, adducted, and internally rotated.243,244 
The Rotator Cuff.
The rotator cuff plays a minor role in static stability likely through the barrier and tenodesis effect of the muscles and tendon. In abduction, the subscapularis limits anterior humeral head translation whereas the infraspinatus and teres minor play a role in limiting posterior translation.150,151,232,252 
Dynamic Stabilizers
The Rotator Cuff.
The muscles of the rotator cuff individually fire to counterbalance each other and the forces created by the other muscles in the shoulder girdle. For example, the subscapularis and the infraspinatus are often contracting at the same time to balance each other and maintain the center position of the humeral head in the glenoid.140,314 In this manner, rotator cuff muscles dynamically stabilize the glenohumeral joint.31,186 As mentioned earlier, contraction of the rotator cuff compresses the humeral head against the glenoid, increasing the role of the labrum for stability and the force needed to translate the head. This compression–concavity effect is well founded in the literature and is a key aspect of dynamic stability by the rotator cuff and other muscles in the shoulder girdle.192,352 Last, in their function to rotate and elevate the humerus, the cuff muscles can dynamically tighten the capsule and ligaments. Each ligament, as discussed above, provides a different checkrein to translation in varying degrees of rotation and adduction–abduction.198,354 
The Biceps Tendon.
The role that the long head of the biceps (LHB) tendon plays in the stabilization of the glenohumeral joint is controversial, but some studies indicate that both passively and dynamically the LHB helps limit anterior, posterior, and inferior translation of the humeral head, especially in adduction.147,152,169 
Other Dynamic Stabilizers.
The deltoid and the scapular stabilizers all likely play some role in the normal stabilization of the glenohumeral joint, but the extent and the exact mechanism of each is not well defined in our current science. For instance, glenoid positioning changes with the motion of the scapula such that protraction by the serratus anterior helps to prevent posterior instability.356 In addition, scapular positioning affects the tension of the glenohumeral capsuloligamentous structures. This mechanism is seen when firing of the trapezius retracts the scapula, increasing the inclination of the glenoid, tightening the superior capsuloligamentous structures, and theoretically preventing against inferior instability.150,152,354,356 
Proprioception.
Other factors such as capsular and muscular proprioception likely play a role. Mechanoreceptors have been found in the capsule and labrum and likely provide positional feedback of humeral head and joint positioning.31 A number of studies have noted altered proprioception in patients with MDI and in patients after a traumatic dislocation.16,31 

Pathoanatomy of Glenohumeral Instability

Labrum, Capsule, and Ligament
Bankart Lesion.
The disruption between the anterior inferior labrum and the glenoid, as seen in traumatic anterior instability, was termed the “essential lesion” by Bankart in 1938.15 Subsequently it has been dubbed the “Bankart lesion.” This disruption is critical in the development of recurrent instability because it serves as the anchor for the IGHLC, which is the primary static stabilizer against anterior and inferior humeral translation in abduction and external rotation. Second, the concavity–compression effect (described above) formed through the combination of dynamic humeral head compression and the increased glenoid concavity by the labrum is disrupted (Fig. 40-12).339 
Figure 40-12
An axial cut of a T2-weighted MR arthrogram with a classic Bankart lesion (arrow).
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Importantly, an isolated labral lesion is likely not enough to lead to gross instability and needs to include detachment of the capsuloligamentous complex. Further, additional capsular deformation or stretch is likely necessary for recurrent instability.330,339 If the IGHLC detaches with a small piece of avulsed glenoid, the lesion is called a bony Bankart. A bony Bankart lesion can also be a “shear” fracture. 
Posterior labral pathology is also noted in the recurrent posterior instability. In fact, there can be a large spectrum of posterior labral pathology ranging from a marginal crack without labral detachment (the “Kim” lesion) to chondral–labral erosion to a detached posterior labral flap (reverse Bankart).5,37,174,359 
Anterior Labral Ligamentous Periosteal Sleeve Avulsion.
In chronic situations, the labrum and the attached periosteum of the anterior glenoid can heal in a medialized position (Fig. 40-13). Nevaisser coined the term anterior labral ligamentous periosteal sleeve avulsion (ALPSA) in 1993 in his description of the lesion.238 Because of the chronicity, ALPSA lesions are technically more difficult to treat and the outcomes have been shown to be inferior to treatment of more acute capsuloligamentous tears (i.e., Bankart lesions).257 
Figure 40-13
An axial cut of a T2-weighted MR arthrogram with a chronic ALPSA lesion (arrow) characterized by medial displacement of the labrum with surrounding fibrous scar tissue.
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Superior Labrum Anterior Posterior Tears.
Though the origin of the IGHLC to the labrum is below the equator of the glenoid, the labral detachment may extend superiorly and include the biceps attachment. Snyder et al. labeled these as superior labrum anterior posterior tears (SLAP) which are generally seen in higher energy trauma.221,327,348 Importantly, the labrum above the equator of the glenoid is normally more loosely attached to the glenoid. 
Humeral Avulsion of Glenohumeral Ligaments.
Though recognized almost 70 years ago by Nicola, the humeral avulsion of glenohumeral ligament (HAGL) lesion has been more recently described and classified.8,42,239,240,294 This injury is a traumatic rupture of the IGHLC at its humeral attachment (Fig. 40-14). Typically it occurs with the arm in hyperabduction and external rotation and often results in instability. The majority is anterior (>90%), but there are six described variations: (1) anterior, (2) anterior bony avulsion, (3) concurrent anterior glenoid-sided avulsion (“floating anterior HAGL”), (4) posterior, (5) posterior bony avulsion, (6) floating posterior HAGL. The avulsion of the posterior IGHLC is a rare cause or recurrent posterior instability. 
Figure 40-14
A coronal cut of a T2-weighted MRI showing a humeral avulsion of the glenohumeral ligament from the humeral neck, or HAGL lesion.
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Other Capsular Pathoanatomy.
Though the pathoanatomy of a Bankart lesion is inherently capsuloligamentous, capsular pathology can occur in the absence of a labral injury or an “essential lesion.” Most commonly, a single or recurrent dislocation can cause tearing and stretching of ligaments which can lead to increased joint volume and further instability.28 
This type of pathology has been implicated in MDI and posterior instability. With these patterns, the capsule is often noted to be “patulous” as it has stretched over time or torn with repetitive microtrauma and healed in an elongated position (Fig. 40-15).268,270 The stretching of the posterior band of the IGHL, specifically, plays an important role and has been shown to correlate with posterior translation of the humeral head.219 However, in some anatomic experiments, posterior dislocations do not occur until an additional anterior structure (rotator interval, anterior capsule, or subscapularis) is released. This “circle” concept of instability, however, is controversial.278,281 Repetitive overhead sports (swimming, volleyball, tennis, baseball) have been associated with this pathology. 
Figure 40-15
An axial cut of a T2-weighted MR arthrogram with a patulous posterior capsule and posterior labral tear (arrow).
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Insufficiency or redundancy can also be specifically seen in the anterior-superior capsule (rotator interval). With this pathology, excessive inferior translation may be seen with external rotation and may be manifested by a positive sulcus sign on physical examination.282 
Last, capsular insufficiency may be seen in an acute trauma, which is quite rare, or after multiple failed surgeries, which is more common. Iatrogenic injury is particularly seen in open surgeries and following thermal capsulorrhaphy. 
Rotator Cuff.
As discussed later, rotator cuff tears are uncommon in patients under 40 years of age with glenohumeral instability, but can be seen in high-energy injuries. Supraspinatus and subscapularis tears are the most common in traumatic events. Subscapularis deficiency, however, should always be evaluated after a failed stabilization procedure, especially after open repairs. Though supraspinatus tears decrease the dynamic stabilization of the joint, subscapularis insufficiency plays a far greater role in instability with loss of tenodesis, compression–concavity, and the direct barrier to anterior dislocation.1,140,152,198,352 
Bone
Glenoid.
Alterations of version can, but do not always, lead to instability. There is no apparent disparity in version between anterior dislocaters and normal subjects, though most anterior dislocations are traumatic.67 However, some patients with significantly retroverted, hypoplastic glenoids are predisposed to recurrent posterior instability (Fig. 40-7).105,129 Posterior glenoid rim fractures or chronic bone loss are sometimes a cause of posterior instability.358 
The pathoanatomy in traumatic anterior instability is most often bone loss of the anterior-inferior glenoid either from an acute fracture/bony Bankart or chronic bony erosion (Fig. 40-16) from multiple dislocations. In both events, the glenoid concavity and surface area are decreased significantly, decreasing the load to dislocation. Gerber and Nyffler found that if the length of the defect was greater than the radius of a best-fit circle of the bottom two-thirds of the glenoid, the force to dislocation was decreased by 70%.97 Burkhart and Debeer coined the phrase the “inverted pair” referring to what the glenoid looks like with chronic anterior inferior bone loss viewing from a superior arthroscopic portal.44 Measuring the bone loss is discussed below, but clinical and biomechanical studies indicate that arthroscopic repair is contraindicated with bone loss greater than 25% because of the high failure rates.44,277 
Figure 40-16
A: An axial cut of a CT scan showing chronic anterior glenoid bone loss (black arrows) a large Hill–Sachs lesion (white arrow).
 
The dashed line represents the plane of the sagittal reconstruction (B) which demonstrates anterior inferior bone loss with a best-fit circle of the inferior two-thirds of the glenoid.
The dashed line represents the plane of the sagittal reconstruction (B) which demonstrates anterior inferior bone loss with a best-fit circle of the inferior two-thirds of the glenoid.
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Figure 40-16
A: An axial cut of a CT scan showing chronic anterior glenoid bone loss (black arrows) a large Hill–Sachs lesion (white arrow).
The dashed line represents the plane of the sagittal reconstruction (B) which demonstrates anterior inferior bone loss with a best-fit circle of the inferior two-thirds of the glenoid.
The dashed line represents the plane of the sagittal reconstruction (B) which demonstrates anterior inferior bone loss with a best-fit circle of the inferior two-thirds of the glenoid.
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Humeral Head.
A compression fracture of the posterosuperolateral humeral head, also known as a Hill–Sachs lesion, is a sequela of an anterior dislocation. The lesion is created with the arm in abduction and external rotation with the posterior humeral head crushed on the anterior glenoid rim.228 With recurrent dislocations, the defect may enlarge170,228 small defects do not often affect treatment. However, with a very large lesion, a progressively enlarging lesion with recurrent dislocations, or with concomitant glenoid bone loss, the relevance of the Hill–Sachs becomes increasingly important in the pathoanatomy of recurrent instability (Fig. 40-16).268,270 Interestingly, Hill–Sachs deformities are not often seen in atraumatic instability. 
Engaging Hill–Sachs lesions are defined as defects which are parallel to the long axis of the glenoid rim in positions of function (abduction and external rotation) and therefore “engage” or contribute to glenohumeral instability. Nonengaging lesions are not parallel to the rim and therefore do not effect stability in positions of function. The type of lesion is determined by the position of the arm during dislocation.44,268,270 
For posterior dislocations, the initial size of a “reverse” Hill–Sachs on the anterior humeral head is an important predictor of who may have recurrent instability (Fig. 40-1). If there is a delay in reduction for weeks, which is not atypical, the lesion enlarges because of rotation of the arm and erosion of bone. In addition, it may become corticated. Lesions greater than 40% of the head appear to have worse outcomes than smaller defects.263 Importantly, however, there is no standard method to measure these lesions. 

Assessment of Glenohumeral Instability

Mechanisms of Injury for Glenohumeral Instability

For some patients, particularly those with recurrent subluxations or MDI the mechanism of instability may be completely atraumatic or the result of repetitive microtrauma. However, most patients with instability have an initial known traumatic episode requiring manual reduction. An estimate of the ratio of traumatic to atraumatic instability is unknown as many with atraumatic instability do not initially seek medical attention. 
Anterior instability occurs through an indirect mechanism with arm abduction, extension, and external rotation with the humeral head challenging the anterior capsule and ligaments, glenoid rim, and rotator cuff. Rarely is the episode a direct blow. For younger patients, athletic injuries are common254,374 whereas for older patients, falls are more typical.127 Less common types of anterior instability (e.g., intrathoracic) are typically extremely high energy. 
Posterior instability occurs through the indirect mechanism of flexion, adduction, and internal rotation with an axial load (e.g., fall on an outstretched arm). Patients may suffer either a posterior dislocation from a single traumatic event or may develop recurrent subluxations from repetitive microtrauma in this position. This repetitive trauma can be seen with American football players, for instance, who keep their arms outstretched in blocking. 
Neuromuscular events (e.g., alcohol withdrawal, seizures or electric shock) account for 30% of all posterior dislocations and lead to instability through violent muscle contraction.301 
In these cases, the internal rotators (latissimus dorsi, pectoralis major, subscapularis) overwhelm the less strong external rotators (teres minor, infraspinatus) forcing the humeral head over the edge of the glenoid fossa. 
Other forms of instability include luxatio erecta, a purely inferior dislocation. This uncommon dislocation occurs with extreme hyperabduction in which the proximal humerus levers against the acromion and dislocates inferiorly. These dislocations are often associated with greater tuberosity fractures or rotator cuff tears. Superior dislocations are extremely rare, but occur with extreme upward force through an adducted arm. 

Associated Injuries with Glenohumeral Instability

Significant injuries can be associated with shoulder instability with most occurring during an initial traumatic episode and relatively few associated with atraumatic and MDI. All types of injuries have been reported. Tearing of the ligamentous and capsular restraints is the most common injury and the key pathoanatomy for recurrent dislocation. However, other associated injuries need to be recognized and cannot be missed as they have implications for prognosis and the ideal treatment for the patient. These injuries differ with the direction of instability. 

Anterior Instability

The Hill–Sachs lesion, described in detail above, is the most common associated injury with anterior instability (Fig. 40-16). The incidence approaches 100% in patients with recurrent dislocations and 40% to 90%47,309 after a single dislocation. With repeated events, the lesion often enlarges and may become clinically symptomatic and further contribute to recurrent instability.228 
Acute fractures at the time of dislocation should be considered and recognized as they affect early management. Specifically, there should be a high suspicion for a nondisplaced neck fracture that may displace with reduction. Atoun et al. reported this association is especially prevalent in first-time dislocators older than 40 with a greater tuberosity fracture and no recognized neck fracture. A fracture of the greater tuberosity fracture was present in 20% of cases. Outcomes, whether with fixation or hemiarthroplasty, are generally poor.10 Treating clinicians should avoid repeated closed reductions and should have a low threshold for reduction in the operating room with full muscle relaxation. 
Greater tuberosity fractures (Fig. 40-3) are the most common and are three times more prevalent in patients older than 30 compared to younger.131 Further, combining greater tuberosity fractures with ultrasound-proven rotator cuff tears, Robinson et al. found a prevalence of 33.4% in a large population-based study of anterior shoulder dislocations.302 Interestingly, an associated fracture decreases the risk of recurrent instability.131,132 
Rotator cuff tears alone are also commonly seen and the incidence increases with age with some reports describing a tear rate of 40% in patients over 40 years of age.266 Patients over 60 years of age had a rate as high as 80%.302 Patients present with weakness and even stiffness, specifically in external rotation and abduction. Also, subscapularis rupture can be a reason for persistent instability in older patients.235,236 
Sometimes rotator cuff tears are misdiagnosed as a neurologic injury, specifically to the axillary nerve.235 However, up to 25% of patients have both a neurologic and a rotator cuff injury, much higher than previously considered.302 This is particularly true for female patients for unclear reasons.302 Early identification of these injuries is critical to best outcomes and therefore for patients older than 40 years of age consideration should be given to ordering an MRI or ultrasound. 
Neurologic injury is common (13% to 65%) because the glenohumeral joint is in close proximity to the brachial plexus.64 An axillary nerve injury is the most common (73%), but often it is not clinically relevant. In a number of studies, up to one-third of patients have EMG evidence of injury, but only 5% having clinically detectable or relevant symptoms.32,302,340 This injury occurs because of traction as well as direct pressure on the nerve as it travels inferior to the subscapularis and below the capsule of the glenohumeral joint. Patients with isolated nerve injuries tend to be younger and male, whereas those with multiple-nerve lesions are more likely to be older than 60 and female.302 Unfortunately, the ability to recover from neurologic injury decreases with age leaving some older patients quite debilitated. 
Because sensory testing alone can be misleading with patients having normal axillary nerve sensation and EMG documented nerve injury, the neurologic examination must include motor (isometric contraction of the deltoid) testing. If a neurologic injury is not recovering in the first 6 weeks, electrophysiologic examination should be performed as a baseline. Prognosis is worse if no recovery is seen in 3 months, but signs of recovery may take upward of 6 months.32,64,302 The timing of surgical intervention is unclear, however intervention at 3 months can be considered if there is no recovery.303 Last, in high-energy settings with a combined shoulder dislocation and brachial plexus injury, consideration should be given to evaluating the cervical spine and nerve root avulsions with the need for early surgical intervention. 
Vascular injuries are rare and are typically seen in older patients who have more fragile vessels. Injury to the axillary artery and vein are the most common injuries characteristically effecting the second part of the vessels, directly behind the pectoralis major.6 The artery is relatively fixed at the lateral margin of pectoralis minor and becomes taut with abduction and external rotation which makes it prone to injury with dislocation or reduction. Occlusion of the artery and vein is more common with luxatio erecta (inferior dislocation).166 Injury with reduction is seen with the elderly, specifically in chronic dislocations with attempted reduction.91 Signs and symptoms include a dysvascular arm or expanding hematoma. Ligation has poor outcomes.177 Urgent consultation with a vascular surgeon is mandatory. 

Posterior Instability

Based on the best, limited evidence, upward of 65% of posterior dislocations have associated injuries.263,301 Fractures are the most common seen in 21% to 34% of cases with neck fractures the most prevalent (19%), followed by lesser tuberosity (14%) and greater tuberosity fractures (8%).301 Importantly, many of the neck fractures are nondisplaced and may be missed or become displaced in an attempted reduction. Reverse Hill–Sachs lesions are seen in 29% to 86% of posterior dislocations (Fig. 40-1).317 Articular cartilage damage is often greater than with true Hill–Sachs lesions. 
Rotator cuff tear injuries are relatively uncommon compared to anterior dislocations with tears seen in 13% of cases.263,301 Interestingly, cuff tears are almost five times more common in the absence of a fracture or reverse Hill–Sachs.263,301 

Signs and Symptoms of Glenohumeral Instability

Presentation of Acute Instability

History.
Some patients with acute instability present to the emergency room usually with an unreduced dislocation from a traumatic event. However, many patients with a subluxation episode or a self-reduced dislocation likely do not present. 
Acute dislocations are typically extremely painful caused by the inciting event and the subsequent spasm of muscle attempting to stabilize the joint. Often the patient can clearly describe the mechanism of injury and shoulder position during dislocation. At other times, this information may be better obtained from an eyewitness. Though anterior dislocations represent the vast majority of acute trauma, suspicion of a posterior dislocation should be raised with a history of a high-energy trauma or strong muscle contraction as seen with a seizure or electric shock. As with any injury, previous episodes, and prior treatments should all be noted. Hand dominance, occupation, activity level, and general health history should also be obtained along with a general trauma survey of the patient. 
A high level of suspicion for a posterior dislocation is needed since upward of 50% of these injuries are missed because of inadequate radiologic evaluation, concomitant fractures, multiple injuries, or an unresponsive, intubated, or sedated patient. 
Rarely, a patient with volitional instability will present to the emergency room for secondary gain. Suspicion should be raised if the story is vague, the mechanism does not coincide with their radiographs or physical findings, or the patient has an inappropriate affect such as minimal pain, or indifference to typically painful reduction maneuvers. 
Physical Examination.
Inspection of the shoulder may reveal localized swelling, or a gross deformity. In thin patients, fullness is often noted in the anterior or posterior shoulder depending on the direction of instability. For anterior dislocations, the humeral head may be palpable or prominent beneath the skin and the lateral edge and posterolateral corner of the acromion may appear prominent. For posterior dislocations, a striking deformity may be absent, though sometimes a posterior fullness can be noted with anterior flattening and a corresponding prominence of the coracoid anteriorly. Notably, posterior dislocations are rare in comparison to their anterior counterpart. 
A complete shoulder examination is often limited by pain; however, before any attempt at shoulder manipulation, a complete neurovascular examination of the upper extremity must be performed and documented. As noted above in the associated injuries section, one electrodiagnostic study reported a 60% rate of axillary nerve injury with anterior dislocations.64 Deltoid strength and axillary nerve sensation should be carefully examined. The musculocutaneous nerve is the next most commonly injured nerve and careful attention to contraction of the biceps or brachialis is important along with testing of sensation in the lateral antebrachial cutaneous distribution on the lateral aspect of the forearm. Although quite rare, vascular injuries following shoulder dislocations have also been reported therefore the brachial, radial, and ulnar pulse should always be examined.194 
Shoulder motion examination will be limited; however, the position of the patient’s arm and their motion limitation may provide insight into both the severity and the direction of the instability. Patients with an anterior dislocation typically will have a limitation to internal rotation and abduction. Patients with a posterior dislocation will often demonstrate limitations in external rotation and abduction with limited passive elevation to 90 degrees. With the rare instance of luxatio erecta, the patient’s arm may be locked in a fully abducted position.371 
After a reduction is performed and verified radiographically, the examination may be limited by guarding. Testing Postreduction range of motion is not advised or should be very limited if the patient is awake. In addition, testing may lead to another dislocation. A thorough neurovascular examination should be reperformed. 

Presentation of Nonacute Instability

History.
Patients who present to the office have a much broader range of signs and symptoms of instability. Some may present to the office for definitive care after being treated at a local emergency room for an acute shoulder dislocation. Others may present with symptoms of recurrent instability and/or symptoms of apprehension. Some may only present with a vague history of pain with an unclear pattern or direction(s) or instability. Because of this variability in presentation, the importance of an accurate and complete history cannot be overemphasized. 
For all types of patients with instability, a standard history should have a checklist of important factors to consider. Background factors include age, handedness, sporting activity, and family history of instability. Next, the circumstances around the initial event need to be elucidated including traumatic/atraumatic event, position of the arm, and documented emergency room reduction. Prior radiographs, especially of the shoulder in the dislocated position, are invaluable. Subsequent history should then be noted including number of documented recurrences, degree of trauma with the recurrences, unilateral or bilateral instability, dislocation during sleep, previous surgeries, presence of pain and location, sensory or strength issues, and whether the instability is voluntary. If a patient can dislocate the shoulder voluntarily, concerns for secondary gain and psychological issues should be raised. However, there should be a distinction between patients who habitually dislocate or subluxate and have a psychogenic component to their instability and those who learn the position of subluxation and can recreate it for examiners. Typically the latter patients try to avoid the provocative position because of discomfort. 
Characteristic History of Anterior Instability.
Patients with recurrent anterior instability almost always had an initial traumatic dislocation with their arm in abduction and external rotation subjected to a large degree of force. Common injuries include a fall during skiing, blocking in basketball, or an arm tackle in football. These events create tearing or avulsion of the inferior capsule and labrum. Also, it should be noted that as instability becomes more chronic, the force needed for both dislocation and reduction decreases, with many episodes requiring only self-reduction. 
Characteristic History of Posterior Instability.
The characteristic history for atraumatic instability includes a patient in their late teens or twenties with apprehension, pain, or even weakness in a provocative position–typically flexion, adduction, and internal rotation. An inciting traumatic event is uncommon, but certain activities consistently create the symptoms. As noted above, many patients can recreate the position of instability, but generally avoid this. Activities of daily living are not affected, but participation in sports can be troublesome. The symptoms may progress, however, to daily life. The disability is variable. 
Characteristic History of Multidirectional Instability.
Patients with MDI may present in a variety of ways. Some present similarly to those with posterior instability with many having a primary posterior component, complicating the diagnosis. Patients often present in their second or third decades with vague complaints of weakness, pain, and decreasing athletic performance without a specific inciting event. This is commonly seen in sports with the potential for repetitive microtrauma like gymnastics and swimming. An inciting event sometimes can be identified after which the symptoms progressed and affected activities of daily living. Many MDI patients, though not all, have hypermobile joints and a subgroup may have Ehlers–Danlos or other syndromes resulting in ligamentous laxity. 
Physical Examination.
The goal of the physical examination is to confirm an impression created by a detailed history. Specifically, the goal is to confirm if the suspected arm position and application of force is consistent in creating apprehension. Though the goal is to not dislocate the shoulder in the examination, it can sometimes happen and should obviously be avoided. Therefore, some of the findings may be subtle, and the ultimate diagnosis may be difficult to establish. 
In patients who have suffered a recent instability episode, associated symptoms may be severe enough to preclude an adequate examination. Basic examination to document glenohumeral joint reduction (radiographic) and neurologic status may be all that can be accomplished during the initial visit. A more thorough evaluation may need to be postponed to a later date when the majority of the pain has subsided. A detailed neurologic examination of the upper extremity must be performed and documented during all clinical evaluations. 
The physical examination should begin with inspection. Any abnormalities such as asymmetry, muscular atrophy, scapular winging, or ecchymosis should be noted. Even early on, at the first visit after a closed reduction, deltoid atrophy can be seen and may represent an axillary nerve injury. Scapular dyskinesis is often associated with instability, as either a cause or result (Fig. 40-17). Careful attention to scapular motion should be noted. Scars indicating previous surgery should be also noted. 
Figure 40-17
Note right posterior incision from a failed capsulorrhaphy.
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Figure 40-17
A patient with recurrent right shoulder instability with scapular dyskinesis and asymmetric motion.
Note right posterior incision from a failed capsulorrhaphy.
Note right posterior incision from a failed capsulorrhaphy.
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Next, the cardinal motions of the shoulder should be measured: Forward elevation in the plane of the scapula, external rotation with the arm in adduction, and internal rotation with use of the spinal levels as a reference (i.e., internal rotation to T10). In addition, external and internal rotation in abduction should be noted which can often be increased (>90) in MDI instability. These measurements should always be compared to the contralateral side and differences between active and passive range of motion should be noted. 
Chronic or missed anterior dislocations typically will have a limitation to internal rotation and abduction. Patients with posterior dislocations will often demonstrate limitations in external rotation and abduction. Also, lack of supination of the forearm has been noted in patients with a chronic posterior dislocation. 
General strength testing is performed with specific maneuvers to identify rotator cuff weakness. This is particularly important for an older individual because the association between rotator cuff tears and shoulder dislocations increases significantly with age. 
Five physical signs of generalized ligamentous laxity according to the Beighton scale should be noted.18 These include passive dorsiflexion of the little finger beyond 90 degrees; passive apposition of the thumb to the ipsilateral forearm; active hyperextension of the elbow beyond 10 degrees; active hyperextension of the knee beyond 10 degrees; and forward flexion of the trunk with the knees fully extended with the palms resting flat on the floor. Each positive test is one point and the first four are performed bilaterally. A score of ≥4 points (out of a possible 9) is diagnostic of generalized joint laxity (Fig. 40-18). 
Figure 40-18
Examples of a patient with generalized ligamentous laxity.
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All of these examinations precede glenohumeral laxity and apprehension testing, which should be done last as it can make patients feel the most uncomfortable. The examination begins with asking the patient to recreate the position of instability. This gives more information than most tests. This clearly determines if the instability is anterior if the position is abduction and external rotation versus cross-body adduction for posterior instability. 
General Tests for Laxity
Drawer Test.
One of the most common examinations of laxity is the “drawer” test. This maneuver is generally performed with the patient sitting with the examiner behind the patient. 
With the forearm on the patient’s lap, the acromion is stabilized with one hand, whereas the other hand manipulates the humeral head for anterior and posterior translation (Fig. 40-19). 
Figure 40-19
The drawer test.
 
Although stabilizing the scapula with one hand, the other hand grasps the humeral head. A gentle pressure is then applied toward the center of the glenoid. At the same time, the humeral head is manually translated in the anterior and in the posterior direction.
Although stabilizing the scapula with one hand, the other hand grasps the humeral head. A gentle pressure is then applied toward the center of the glenoid. At the same time, the humeral head is manually translated in the anterior and in the posterior direction.
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Figure 40-19
The drawer test.
Although stabilizing the scapula with one hand, the other hand grasps the humeral head. A gentle pressure is then applied toward the center of the glenoid. At the same time, the humeral head is manually translated in the anterior and in the posterior direction.
Although stabilizing the scapula with one hand, the other hand grasps the humeral head. A gentle pressure is then applied toward the center of the glenoid. At the same time, the humeral head is manually translated in the anterior and in the posterior direction.
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For normal shoulders, this translation is smooth with a firm endpoint assessing the static restraints. If the translation is excessive, the patient has increased laxity, but not necessarily instability. If the maneuver reproduces the clinical symptoms of apprehension or pain, a presumed diagnosis of instability (anterior or posterior) may be established if consistent with the history and other examination findings. This is a reliable test when the patient is able to relax the shoulder muscle sufficiently and allow the maneuver to be performed without tension.76,94 
Load and Shift Test.
A variant of the drawer test is the load and shift test.94,322 The patient is placed supine with arm abducted to 60 degrees. An axial pressure is applied to the humeral head to press the humeral head against the glenoid with the forearm in neutral position. Similar to the drawer test, the humeral head is then grasped and translated in either the anterior or posterior direction to assess for laxity and pain. Translation of the head to the glenoid rim is graded 1+; translation over the rim with spontaneous reduction is graded 2+; and dislocation without spontaneous reduction is grade 3+.3 The test may recreate the symptoms of instability. 
Sulcus Test.
In the sulcus test, the patient is seated with their arm relaxed at their side and the arm is then pulled downward. A positive test reveals a “sulcus” or hollow area below the acromion. By placing the shoulder in external rotation, the sulcus test can also be used to estimate the laxity of the rotator interval structures (the coracohumeral and the SGHLs) as this maneuver places these structures under tension. The test is measured by noting the translation of the humeral head away from the acromion. Less than 1 cm of translation is graded as 1+; 1 to 2 cm is 2+; greater than 2 cm is 3+. Importantly, the sulcus sign is generally used to test for inferior laxity and is considered positive for inferior instability if the patient also has apprehension or even pain. It is often positive in many patients with MDI or posterior instability (Fig. 40-20).233 
Figure 40-20
The sulcus test for inferior instability of the shoulder.
 
With the patient in the sitting position, a downward traction is placed on the adducted arm (A). With a positive test (B), excessive inferior translation produces a dimple (arrow) on the lateral aspect of the acromion. By performing this test with the arm in external rotation, the maneuver can also be used to test the integrity of the rotator interval structures.
With the patient in the sitting position, a downward traction is placed on the adducted arm (A). With a positive test (B), excessive inferior translation produces a dimple (arrow) on the lateral aspect of the acromion. By performing this test with the arm in external rotation, the maneuver can also be used to test the integrity of the rotator interval structures.
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Figure 40-20
The sulcus test for inferior instability of the shoulder.
With the patient in the sitting position, a downward traction is placed on the adducted arm (A). With a positive test (B), excessive inferior translation produces a dimple (arrow) on the lateral aspect of the acromion. By performing this test with the arm in external rotation, the maneuver can also be used to test the integrity of the rotator interval structures.
With the patient in the sitting position, a downward traction is placed on the adducted arm (A). With a positive test (B), excessive inferior translation produces a dimple (arrow) on the lateral aspect of the acromion. By performing this test with the arm in external rotation, the maneuver can also be used to test the integrity of the rotator interval structures.
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Gagey Hyperabduction Test.
Gagey and Gagey84 recently described another test of inferior laxity and instability. In this test, the examiner stands behind the patient with their forearm pushed down against the shoulder girdle whereas using the other hand to gently passively abduct the patient’s arm. The patient’s elbow is flexed to 90 degrees (Fig. 40-21). Patients who can be abducted over 105 degrees have increased laxity whereas those with symptoms of apprehension suggest a diagnosis of inferior instability. Normal abduction should be 85 to 90 degrees. This test was positive in 85% of patients with known instability treated with anterior-inferior capsulorrhaphy. It is typically positive with MDI and should be performed for all patients with posterior instability as there is frequently a bidirectional component. 
Figure 40-21
The Gagey abduction test for inferior laxity.
 
The examiner stands behind the patient with their forearm pushed down against the shoulder girdle using the other hand to gently passively abduct the patient’s arm. Normal abduction is about 90 degrees as seen in this patient. Abduction over 105 degrees reflects increased laxity, whereas symptoms of apprehension suggest a diagnosis of inferior instability.
The examiner stands behind the patient with their forearm pushed down against the shoulder girdle using the other hand to gently passively abduct the patient’s arm. Normal abduction is about 90 degrees as seen in this patient. Abduction over 105 degrees reflects increased laxity, whereas symptoms of apprehension suggest a diagnosis of inferior instability.
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Figure 40-21
The Gagey abduction test for inferior laxity.
The examiner stands behind the patient with their forearm pushed down against the shoulder girdle using the other hand to gently passively abduct the patient’s arm. Normal abduction is about 90 degrees as seen in this patient. Abduction over 105 degrees reflects increased laxity, whereas symptoms of apprehension suggest a diagnosis of inferior instability.
The examiner stands behind the patient with their forearm pushed down against the shoulder girdle using the other hand to gently passively abduct the patient’s arm. Normal abduction is about 90 degrees as seen in this patient. Abduction over 105 degrees reflects increased laxity, whereas symptoms of apprehension suggest a diagnosis of inferior instability.
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Specific Examinations for Anterior Instability
Apprehension Tests.
The “apprehension” test, originally described by Rowe and Zarins,310 can be performed with the patient supine or sitting with the examiner behind the patient. From a position of 90 degrees of abduction and neutral rotation, the shoulder is externally rotated until it reaches its maximal limit or until the feeling of apprehension is reported by the patient (Fig. 40-22). It may be necessary to hold the arm in this position for 1 to 2 minutes to fatigue the subscapularis before apprehension is felt from capsular insufficiency. Although pain may be used as an indicator for instability, it is typically not as specific or as reliable as apprehension in documenting anterior instability.76,331 In the relocation test as described by Jobe et al.,158 a posteriorly directed force is placed on the anterior aspect of the shoulder to eliminate the feeling of apprehension (Fig. 40-23). 
Figure 40-22
The apprehension and the fulcrum tests for anterior instability.
 
In the apprehension test, the shoulder is abducted and externally rotated such that it is in a position vulnerable to dislocation with the patient in supine position (A). Symptomatic patients will report the sensation of apprehension or “getting ready to dislocate.” In the fulcrum test, this sensation of instability is accentuated by placing an anteriorly directed force on the posterior humeral head (B).
In the apprehension test, the shoulder is abducted and externally rotated such that it is in a position vulnerable to dislocation with the patient in supine position (A). Symptomatic patients will report the sensation of apprehension or “getting ready to dislocate.” In the fulcrum test, this sensation of instability is accentuated by placing an anteriorly directed force on the posterior humeral head (B).
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Figure 40-22
The apprehension and the fulcrum tests for anterior instability.
In the apprehension test, the shoulder is abducted and externally rotated such that it is in a position vulnerable to dislocation with the patient in supine position (A). Symptomatic patients will report the sensation of apprehension or “getting ready to dislocate.” In the fulcrum test, this sensation of instability is accentuated by placing an anteriorly directed force on the posterior humeral head (B).
In the apprehension test, the shoulder is abducted and externally rotated such that it is in a position vulnerable to dislocation with the patient in supine position (A). Symptomatic patients will report the sensation of apprehension or “getting ready to dislocate.” In the fulcrum test, this sensation of instability is accentuated by placing an anteriorly directed force on the posterior humeral head (B).
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Figure 40-23
The relocation test for anterior instability.
 
With the patient supine, the shoulder is abducted and externally rotated such that it is in a position vulnerable to dislocation. With a positive relocation test, the apprehension is reduced with a posteriorly directed force on the shoulder.
With the patient supine, the shoulder is abducted and externally rotated such that it is in a position vulnerable to dislocation. With a positive relocation test, the apprehension is reduced with a posteriorly directed force on the shoulder.
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Figure 40-23
The relocation test for anterior instability.
With the patient supine, the shoulder is abducted and externally rotated such that it is in a position vulnerable to dislocation. With a positive relocation test, the apprehension is reduced with a posteriorly directed force on the shoulder.
With the patient supine, the shoulder is abducted and externally rotated such that it is in a position vulnerable to dislocation. With a positive relocation test, the apprehension is reduced with a posteriorly directed force on the shoulder.
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A variation of this test in which an anterior-directed pressure is added to the humeral head is called the crank test (Fig. 40-24). The fulcrum test is performed with the patient supine with the shoulder off the edge of the examination table and the arm in 90 degrees of abduction. The examiner places one hand behind the shoulder which acts as a fulcrum as the examiner’s other hand is used to gently extend and externally rotate the patients arm. A test is positive if apprehension is felt by the patient (Fig. 40-22). 
Figure 40-24
The crank test for anterior instability.
 
The shoulder is abducted and externally rotated such that it is in a position vulnerable to anterior dislocation with the patient in sitting position. With an anteriorly directed force on the posterior humeral head, the instability is accentuated to cause the sensation of apprehension or “getting ready to dislocate.”
The shoulder is abducted and externally rotated such that it is in a position vulnerable to anterior dislocation with the patient in sitting position. With an anteriorly directed force on the posterior humeral head, the instability is accentuated to cause the sensation of apprehension or “getting ready to dislocate.”
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Figure 40-24
The crank test for anterior instability.
The shoulder is abducted and externally rotated such that it is in a position vulnerable to anterior dislocation with the patient in sitting position. With an anteriorly directed force on the posterior humeral head, the instability is accentuated to cause the sensation of apprehension or “getting ready to dislocate.”
The shoulder is abducted and externally rotated such that it is in a position vulnerable to anterior dislocation with the patient in sitting position. With an anteriorly directed force on the posterior humeral head, the instability is accentuated to cause the sensation of apprehension or “getting ready to dislocate.”
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Finally, the surprise test is another variation of the apprehension test where the examination starts with a posteriorly directed force on the anterior shoulder. As this force is stabilizing the glenohumeral joint, the patient does not experience apprehension even when the shoulder is placed in abduction and maximal external rotation. By abruptly removing this force, the patient will suddenly experience apprehension or pain. Although all these maneuvers can detect anterior instability, a recent study has suggested that the surprise test may be the most sensitive.199 
Studies have found the specificity of the anterior apprehension, relocation, and surprise tests to be above 90%.199 The anterior drawer test, on the other hand, is less specific. The sensitivity of all these tests range from approximately 50% to 70%.76 In addition, when pain is used instead of the feeling of apprehension both the sensitivity and specificity are poor.156 
Specific Examinations for Posterior Instability.
Posterior instability is best tested with the patient sitting or standing for easy visualization of the posterior musculature and bony contours. With very unstable patients, a posteriorly dislocated head can be seen with adduction and internal rotation. Most patients can demonstrate their subluxation and the position of apprehension. 
The main provocative maneuver is the jerk test. With the arm elevated to 90 degrees and internally rotated (Fig. 40-25)176 an axial load is placed such that the humeral head is compressed against the glenoid and the scapula is stabilized by the examiner’s other hand. This can be easily accomplished by pushing axially against the flexed elbow. By gradually adducting the shoulder, the humeral head may subluxate or even dislocate posteriorly and produce a sudden jerk. When the shoulder is returned to its original position, the humeral head will abruptly reduce back onto the glenoid and produce another jerk. The findings from this test can be quite dramatic in patients with posterior instability, but can be difficult to create if the patient is not fully relaxed. Some authors have suggested a painful test has a worse prognosis with nonoperative treatment.176 
Figure 40-25
The jerk test for posterior instability.
 
With the patient in either sitting or supine position, the arm is abducted and internally rotated. An axial load is then placed on the humerus while the arm is moved horizontally across the body. With a positive test, a sudden jerk occurs when the humeral head slides off of the back of the glenoid and when it is reduced back onto the glenoid.
With the patient in either sitting or supine position, the arm is abducted and internally rotated. An axial load is then placed on the humerus while the arm is moved horizontally across the body. With a positive test, a sudden jerk occurs when the humeral head slides off of the back of the glenoid and when it is reduced back onto the glenoid.
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Figure 40-25
The jerk test for posterior instability.
With the patient in either sitting or supine position, the arm is abducted and internally rotated. An axial load is then placed on the humerus while the arm is moved horizontally across the body. With a positive test, a sudden jerk occurs when the humeral head slides off of the back of the glenoid and when it is reduced back onto the glenoid.
With the patient in either sitting or supine position, the arm is abducted and internally rotated. An axial load is then placed on the humerus while the arm is moved horizontally across the body. With a positive test, a sudden jerk occurs when the humeral head slides off of the back of the glenoid and when it is reduced back onto the glenoid.
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Specific Examinations for Multidirectional Instability.
There is no specific test for MDI, but inferior instability, by definition, is a major aspect of the pathology. Therefore, specific tests of inferior laxity such as the sulcus sign and the Gagey hyperabduction test may be symptomatic along with other laxity tests (drawer and load and shift). Importantly, signs of hyperlaxity may be present in other joints or the contralateral shoulder, but may not be symptomatic. Because scapular dyskinesis has been observed as either a cause or result of MDI, asymmetry of the scapula in both the resting state and with forward motion should be noted. 

Imaging and Other Diagnostic Studies for Glenohumeral Instability

The Grashey View

Because of the oblique position of the scapula on the thorax, in a routine anteroposterior (AP) radiograph of the entire shoulder, the shadow of the humeral head will overlap with the glenoid fossa. This view is difficult to interpret with respect to the glenohumeral joint (Fig. 40-26A). 
Figure 40-26
Technique for obtaining anteroposterior (AP) thorax (A) and true AP (B) radiographs of the shoulder.
 
In an AP view, the radiograph actually represents an oblique view of the shoulder joint. In a true AP view, the x-ray beam is parallel to the joint so that there is minimal overlap between the humeral head and the glenoid surface. The radiographic views of the shoulder AP (C) and shoulder true AP (D) are demonstrated.
In an AP view, the radiograph actually represents an oblique view of the shoulder joint. In a true AP view, the x-ray beam is parallel to the joint so that there is minimal overlap between the humeral head and the glenoid surface. The radiographic views of the shoulder AP (C) and shoulder true AP (D) are demonstrated.
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Figure 40-26
Technique for obtaining anteroposterior (AP) thorax (A) and true AP (B) radiographs of the shoulder.
In an AP view, the radiograph actually represents an oblique view of the shoulder joint. In a true AP view, the x-ray beam is parallel to the joint so that there is minimal overlap between the humeral head and the glenoid surface. The radiographic views of the shoulder AP (C) and shoulder true AP (D) are demonstrated.
In an AP view, the radiograph actually represents an oblique view of the shoulder joint. In a true AP view, the x-ray beam is parallel to the joint so that there is minimal overlap between the humeral head and the glenoid surface. The radiographic views of the shoulder AP (C) and shoulder true AP (D) are demonstrated.
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A “true” anterior–posterior radiograph of the glenohumeral joint is obtained when the x-ray beam is parallel to the glenoid fossa, roughly perpendicular to the scapular body (Fig. 40-26B). The x-ray beam is angled 35 to 45 degrees oblique to the sagittal plane of the body, centered on the coracoid process with the plate flat on the scapula. In this view, described by Grashey in 1923,104 there is no overlap between the glenoid and the humeral head. In normal shoulders, a concave contour of the glenoid fossa should match the convex articular surface of the humeral head. If any overlap is seen between the glenoid and the humeral head, a dislocation should be suspected (Fig. 40-27). Although anterior dislocations are usually readily apparent, posterior dislocations can be very subtle on the AP radiograph. Inferior glenoid fractures can also be seen on this view, though the injury is best seen on the West-point axillary view described later. In addition, it has been noted by several authors that the loss of 5 mm of the inferior sclerotic line of the glenoid on the Grashey view is moderately sensitive (50% to 60%), but highly specific to anterior rim defects associated with recurrent anterior instability (Fig. 40-28).14,154 
Figure 40-27
AP shoulder radiograph of a posterior dislocation.
 
Note the widened space between the anterior glenoid rim and the humeral head.
Note the widened space between the anterior glenoid rim and the humeral head.
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Figure 40-27
AP shoulder radiograph of a posterior dislocation.
Note the widened space between the anterior glenoid rim and the humeral head.
Note the widened space between the anterior glenoid rim and the humeral head.
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Figure 40-28
 
A: Grashey view with loss of the anterior sclerotic line (black arrows) which is moderately sensitive, but highly specific for anterior rim fractures of the inferior glenoid (white arrow). B: Corresponding MRI showing a bony Bankart lesion.
A: Grashey view with loss of the anterior sclerotic line (black arrows) which is moderately sensitive, but highly specific for anterior rim fractures of the inferior glenoid (white arrow). B: Corresponding MRI showing a bony Bankart lesion.
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Figure 40-28
A: Grashey view with loss of the anterior sclerotic line (black arrows) which is moderately sensitive, but highly specific for anterior rim fractures of the inferior glenoid (white arrow). B: Corresponding MRI showing a bony Bankart lesion.
A: Grashey view with loss of the anterior sclerotic line (black arrows) which is moderately sensitive, but highly specific for anterior rim fractures of the inferior glenoid (white arrow). B: Corresponding MRI showing a bony Bankart lesion.
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Axillary Views

An AP radiograph of the glenohumeral joint must be accompanied by an orthogonal view to document the location of the humeral head relative to the glenoid fossa. An axillary view is preferable because it can clearly display the bony anatomy and whether the humeral head is located. The view unambiguously shows the direction and magnitude of humeral head displacement and some associated fractures of both the humeral head and glenoid can be seen. 
The standard axillary radiograph is obtained by placing the cassette on the superior aspect of the shoulder and directing the x-ray beam between the thorax and the abducted arm (Fig. 40-29A). For patients who cannot abduct the arm, two additional techniques have also been described. The trauma axillary lateral is performed with the patient supine with the injured slinged arm held by a foam wedge or pillow. This view requires minimal abduction (Fig. 40-29B). Alternatively, the Velpeau axillary lateral (Fig. 40-30) is performed with the patient leaning backward with their arm in a sling until the shoulder is over a horizontal cassette at the lower back. The x-ray beam is directed superior to inferior.33 
Figure 40-29
Techniques for obtaining axillary lateral (A) and trauma axillary lateral (B) view radiographs.
 
The radiographic view of the axillary lateral (C) is demonstrated.
The radiographic view of the axillary lateral (C) is demonstrated.
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Figure 40-29
Techniques for obtaining axillary lateral (A) and trauma axillary lateral (B) view radiographs.
The radiographic view of the axillary lateral (C) is demonstrated.
The radiographic view of the axillary lateral (C) is demonstrated.
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Figure 40-30
Positioning of the patient for the Velpeau axillary lateral view radiograph.
Rockwood-ch040-image030.png
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The West Point axillary provides a tangential view of the anterior glenoid and is particularly useful in the identification of glenoid rim fractures which are missed on the standard axillary and its trauma modifications. It is taken with the patient in a prone position with the cassette placed on the superior aspect of the shoulder. The x-ray beam is directed 25 degrees downward from the horizontal and inward toward the axilla (Fig. 40-31).304 
Figure 40-31
West Point view for the identification of a glenoid rim lesion.
 
This radiograph is taken with the patient in the prone position. The beam is angled approximately 25 degrees from the midsagittal plane (A) to provide a tangential view of the glenoid. In addition, the beam is angled 25 degrees downward (B) to highlight the anterior and posterior aspects of the glenoid. In this fashion, the entire glenoid rim can be clearly visualized (C).
This radiograph is taken with the patient in the prone position. The beam is angled approximately 25 degrees from the midsagittal plane (A) to provide a tangential view of the glenoid. In addition, the beam is angled 25 degrees downward (B) to highlight the anterior and posterior aspects of the glenoid. In this fashion, the entire glenoid rim can be clearly visualized (C).
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Figure 40-31
West Point view for the identification of a glenoid rim lesion.
This radiograph is taken with the patient in the prone position. The beam is angled approximately 25 degrees from the midsagittal plane (A) to provide a tangential view of the glenoid. In addition, the beam is angled 25 degrees downward (B) to highlight the anterior and posterior aspects of the glenoid. In this fashion, the entire glenoid rim can be clearly visualized (C).
This radiograph is taken with the patient in the prone position. The beam is angled approximately 25 degrees from the midsagittal plane (A) to provide a tangential view of the glenoid. In addition, the beam is angled 25 degrees downward (B) to highlight the anterior and posterior aspects of the glenoid. In this fashion, the entire glenoid rim can be clearly visualized (C).
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The Scapular Y View

The scapular Y view is a second orthogonal view to the Grashey view; however, it is difficult to understand the bony anatomy specifically with regards to the location of humeral head in relation to the glenoid fossa. 
The radiograph is obtained by placing the cassette on the anterolateral aspect of the shoulder and directing the x-ray beam medial to lateral, parallel to the spine of the scapula (Fig. 40-32).227 The x-ray shadows outline the scapula as the letter “Y”—hence the name of this view. The two upper limbs of the letter Y represent the scapula spine and the coracoid process, respectively, whereas the inferior limb of the Y represents the scapular body. The glenoid fossa is located in the center of the Y where all the limbs intersect and where the humeral head should be centered. 
Figure 40-32
Technique for obtaining a scapula lateral, also known as the “Y,” view radiograph.
 
With the cassette placed on the anterior lateral aspect of the shoulder, the x-ray beam is directed parallel to the plane of the scapula.
With the cassette placed on the anterior lateral aspect of the shoulder, the x-ray beam is directed parallel to the plane of the scapula.
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Figure 40-32
Technique for obtaining a scapula lateral, also known as the “Y,” view radiograph.
With the cassette placed on the anterior lateral aspect of the shoulder, the x-ray beam is directed parallel to the plane of the scapula.
With the cassette placed on the anterior lateral aspect of the shoulder, the x-ray beam is directed parallel to the plane of the scapula.
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The Apical Oblique View

Sometimes referred to as the Garth view, the apical oblique view clearly reveals the anterior inferior and posterior superior glenoid rims. Acute anterior inferior fractures or chronic bone loss associated with recurrent instability can be seen on this view. Additionally, Hill–Sachs deformities are seen as the posterolateral humeral head is well defined. 
In this view, the patient is upright with the cassette flat against the scapula. Like the Grashey view, the x-ray beam is directed orthogonal to the scapula to get a “true” AP of the joint. In addition, a 45-degree caudal tilt is used so the beam is directed downward and medial to lateral87,88 (Fig. 40-33). 
Figure 40-33
Apical oblique view for the identification of a glenoid rim lesion.
 
This radiograph is taken with the beam angled approximately 45 degrees (A) to provide a “true AP” view of the glenoid. In addition, the beam is angled 45 degrees downward (B) to highlight the anterior inferior aspect of the glenoid. As such, a bony defect in the anterior inferior aspect of the glenoid (C) can be easily visualized. (Modified from Garth WP, Slappey CE, Ochs CW. Roentgenographic demonstration of instability of the shoulder: The apical oblique projection. A technical note. J Bone Joint Surg 1984;66-A:1450–1453.)
This radiograph is taken with the beam angled approximately 45 degrees (A) to provide a “true AP” view of the glenoid. In addition, the beam is angled 45 degrees downward (B) to highlight the anterior inferior aspect of the glenoid. As such, a bony defect in the anterior inferior aspect of the glenoid (C) can be easily visualized. (Modified from Garth WP, Slappey CE, Ochs CW. Roentgenographic demonstration of instability of the shoulder: The apical oblique projection. A technical note. J Bone Joint Surg 1984;66-A:1450–1453.)
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Figure 40-33
Apical oblique view for the identification of a glenoid rim lesion.
This radiograph is taken with the beam angled approximately 45 degrees (A) to provide a “true AP” view of the glenoid. In addition, the beam is angled 45 degrees downward (B) to highlight the anterior inferior aspect of the glenoid. As such, a bony defect in the anterior inferior aspect of the glenoid (C) can be easily visualized. (Modified from Garth WP, Slappey CE, Ochs CW. Roentgenographic demonstration of instability of the shoulder: The apical oblique projection. A technical note. J Bone Joint Surg 1984;66-A:1450–1453.)
This radiograph is taken with the beam angled approximately 45 degrees (A) to provide a “true AP” view of the glenoid. In addition, the beam is angled 45 degrees downward (B) to highlight the anterior inferior aspect of the glenoid. As such, a bony defect in the anterior inferior aspect of the glenoid (C) can be easily visualized. (Modified from Garth WP, Slappey CE, Ochs CW. Roentgenographic demonstration of instability of the shoulder: The apical oblique projection. A technical note. J Bone Joint Surg 1984;66-A:1450–1453.)
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The Stryker Notch View

The Stryker notch view is the best to characterize the Hill–Sachs defect and the posterior-superior humeral head (Fig. 40-34).115 The film is taken with the patient supine with the cassette under the shoulder. The palm of the hand rests on the patient’s head with the arm forward flexed such that the bent elbow is over the face and pointed straight upward. The x-ray beam is angled approximately 10 degrees caudal relative to a vertical line orthogonal to the patient’s torso. The beam is centered over the coracoid. 
Figure 40-34
Stryker notch view for humeral head defects.
 
The patient is in the supine position with the arm flexed to 120 degrees so that the hand can be placed on top of the head (A). The x-ray beam is then angled approximately 10 degrees. The radiograph (B) can clearly reveal the presence of any osseous defects (arrow). (Modified from Hall RH, Isaac F, Booth CH. Dislocations of the shoulder with special reference to accompanying small fractures. J Bone Joint Surg 1959;41:489–494.)
The patient is in the supine position with the arm flexed to 120 degrees so that the hand can be placed on top of the head (A). The x-ray beam is then angled approximately 10 degrees. The radiograph (B) can clearly reveal the presence of any osseous defects (arrow). (Modified from Hall RH, Isaac F, Booth CH. Dislocations of the shoulder with special reference to accompanying small fractures. J Bone Joint Surg 1959;41:489–494.)
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Figure 40-34
Stryker notch view for humeral head defects.
The patient is in the supine position with the arm flexed to 120 degrees so that the hand can be placed on top of the head (A). The x-ray beam is then angled approximately 10 degrees. The radiograph (B) can clearly reveal the presence of any osseous defects (arrow). (Modified from Hall RH, Isaac F, Booth CH. Dislocations of the shoulder with special reference to accompanying small fractures. J Bone Joint Surg 1959;41:489–494.)
The patient is in the supine position with the arm flexed to 120 degrees so that the hand can be placed on top of the head (A). The x-ray beam is then angled approximately 10 degrees. The radiograph (B) can clearly reveal the presence of any osseous defects (arrow). (Modified from Hall RH, Isaac F, Booth CH. Dislocations of the shoulder with special reference to accompanying small fractures. J Bone Joint Surg 1959;41:489–494.)
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Computed Tomography and Magnetic Resonance Imaging

Computed tomography (CT) and magnetic resonance imaging (MRI) are often necessary for full understanding of the pathogenesis of glenohumeral instability. A CT scan may be useful in the acute setting when limited quality radiographs or other circumstances do not clearly demonstrate glenohumeral joint pathology. In addition, CT is necessary to determine the size and displacement of a suspected glenoid fracture or the presence of proximal humerus fractures as routine radiographs can be difficult to interpret. In the acute setting, there is limited need for an MRI. 
In the subacute (first office visit of a first time dislocater) or a nonacute setting, if consideration is given to surgical treatment, MRI (in comparison to CT) is considered the standard of reference for the determination of pathoanatomy because the majority of injuries are capsuloligamentous. MRI is also necessary to evaluate for rotator cuff tears and humeral avulsions of the glenohumeral ligaments (HAGL). Importantly, MR arthrography (the injection of contrast into the joint) has been shown to be more sensitive than conventional MRI in the detection of labral, capsule, and rotator cuff tears and is the investigation of choice for soft tissue pathology.50,191 
Many of the studies comparing MR arthrography to conventional MRI, however, were performed in the 1990s with lower resolution (non 3-Tesla) scanners.50 More recent studies confirm a high sensitivity and specificity for both MR arthrography and conventional MRI, but still favor MR arthrography.250 In MR arthrography, labral and rotator cuff tears all had sensitivities >95% and specificities of nearly 100%; conventional 3-T MRI had similar specificities,250 but lower sensitivities in the 80% to 90% range.162,202 
As discussed later in this section, CT scan with three-dimensional reconstructions is the ideal study for the evaluation of bony pathology: Acute fracture, anterior-inferior glenoid humeral bone loss, and Hill–Sachs deformities. The addition of contrast dye for CT arthrography allows for the visualization of soft tissue pathology such as rotator cuff tears and capsular lesions. The sensitivity of CT arthrography approaches conventional MRI in evaluating labral tears (80% to 90%) with specificities in the 90% range. However, CT arthrography still falls short of MR arthrography.50,349 In addition, extracapsular soft tissue is not well seen249 and the quality of imaging still varies considerably between institutions. 

Defining Glenoid Bone Loss

Radiographs are moderately sensitive for identifying glenoid bone loss,21,26,88 but have little value in measuring clinically relevant loss. CT scans with three-dimensional reconstructions and modeling are the gold standard as MRI may underestimate the degree of bone loss.148 With these scans and contralateral imaging of the shoulder, a best-fit circle of the inferior two-thirds of the normal shoulder can be superimposed onto the effected side to estimate the amount of bone loss.26,200 The average diameter of this circle for a normal glenoid is approximately 24 mm.141 Numerous methods have been used for the estimation of bone loss, but the simplest involves using the diameter to calculate this percentage (Fig. 40-35).200 
Figure 40-35
Using the best-fit circle of the inferior two-thirds of the glenoid, total glenoid bone loss can be estimated with the equation in the text.
 
The average glenoid diameter is 24 mm and 7.5 mm of anterior bone loss corresponds to approximately 25% of total loss.
The average glenoid diameter is 24 mm and 7.5 mm of anterior bone loss corresponds to approximately 25% of total loss.
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Figure 40-35
Using the best-fit circle of the inferior two-thirds of the glenoid, total glenoid bone loss can be estimated with the equation in the text.
The average glenoid diameter is 24 mm and 7.5 mm of anterior bone loss corresponds to approximately 25% of total loss.
The average glenoid diameter is 24 mm and 7.5 mm of anterior bone loss corresponds to approximately 25% of total loss.
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According to Lo et al.,200 an anterior defect of 7.5 mm corresponds to approximately 25% of total bone loss. Importantly, small differences in the size of the best-fit circle along with the angle in which the sagittal reconstructions are made relative to the scapular body may make a significant difference in the measurements. 

Defining the Hill–Sachs Defect

The Hill–Sachs lesion, especially if it is large, can sometimes be visualized on routine radiographs especially the “true” AP radiographs of the shoulder as well as a standard axillary view. A true AP view with full internal rotation of the arm can allow better visualization, however, none of these views are fully sensitive. The Stryker–Notch view is the most sensitive in identifying the Hill–Sachs and is regarded as the best view to gauge its relative size.115 Ultimately, however, CT scans and three-dimensional imaging and reconstructions are ideal: However, there is no universally standard way to measure the size or significance. Many methods have used percentage of total articular surface as a gauge of the defect, but unlike the developments in measuring glenoid bone loss, better methods are still required. 

Diagnostic Arthroscopy

Ultimately, if there is any question of the diagnosis, or the amount of glenoid or humeral bone loss, a diagnostic arthroscopy is an ideal tool for clarification. Lo et al. described a method of quantifying glenoid bone loss by measuring glenoid width with the “bare area” as a reference point. This relatively constant spot is defined by absent cartilage in the center of the native glenoid.199 In addition, the size, engagement, and clinical relevance of the Hill–Sachs can be determined. 

Author’s Preferred Diagnostic Work-Up

 
 
Acute Instability
 

In the emergency room, with a reduced dislocation, we prefer a true AP or Grashey view to evaluate the concentricity of the joint and signs of glenoid or proximal humerus fracture; an apical oblique or Garth view to better view a glenoid fracture; and a Velpeau or trauma axillary to clearly determine the reduction of the joint. None of these views require the patient to remove the sling. If there is any question of joint reduction, a CT scan is performed—though this is uncommon.

 
Nonacute Instability
 

The evaluation of the patient with recurrent instability in the office setting requires the same views as in the acute setting, but a Stryker–Notch view is added to evaluate for the Hill–Sachs defect. If there is little concern for bone loss based on the history and radiographs, a high-resolution conventional MRI is our preferred study to not only evaluate for a capsular tear but for other pathology such as a HAGL or a rotator cuff tear. Given the high quality of current MRI scanners as well as the invasive nature and the additional cost of arthrography, MR arthrography is not routinely used.

 

If bone loss is a major concern, a CT scan is ordered. With the improvement of CT arthrograms, however, this may be the single ideal study, however, the quality of the imaging differs between institutions. Consideration of patient age, the additional radiation of CT scans, and the invasive nature is always considered before pursuing this study.

 

Last, if there is any question of the degree of bone loss, the engagement of the Hill–Sachs, the quality of tissue or the presence of other intra-articular pathology, a diagnostic arthroscopy is performed.

Outcome Measures for Glenohumeral Instability

General health and general shoulder scores such as the Medical Outcomes Study 36-item Short Form (SF-36) and American Shoulder and Elbow Surgeons (ASES) score, respectively, have been used to measure instability outcomes. However, these scores are not ideal and subsequently there are two specific glenohumeral instability scores that have been developed: the Western Ontario Shoulder Instability Index (WOSI) and the Oxford Instability Score. 
The Rowe score was described by Carter Rowe in his classic 1978 article evaluating long-term results of Bankart repairs.307 This unvalidated score has a maximum of 100 points and rates patient outcome based on three domains about the shoulder: Stability (50 points), motion (20 points), and function (30 points). Because this was the first score to be developed, it has a number of weaknesses. First, the various weights of the three items are arbitrary and unsupported. Second, how the three domains are evaluated is unclear. For instance, it is not clear if the motion measurements are active or passive and how the three motions (external rotation, forward elevation, and internal rotation) are combined to make up the 20 points. For these reasons, this score should only be used for historical comparison in addition to a modern validated outcome score. 
The WOSI is a validated score that was established in 1998.178 The test consists of 21 questions with 4 domains: Physical symptoms (10 questions); sports, recreation, and work (4 questions); lifestyle (4 questions); and emotions (3 questions). The score ranges from 0 to 2100 with a lower score representing a better outcome. A percentage score is calculated per the following formula:   
The estimate for a minimal clinically important difference (MCID) is 220 points or 10.4%. For moderate and large differences, the estimates are 469 (22.3%) and 527 (25%), respectively. The WOSI has been shown to be more responsive to measuring shoulder instability than the following scores in order: Rowe, DASH, Constant, ASES, UCLA, and SF-12. 
The Oxford Shoulder Instability Questionnaire was developed in 1999 by Dawson et al.62 This is a 12-item questionnaire with each item scored from 1 to 5 with the higher numbers reflecting greater severity. The numbers are combined to form a score from 12 to 60 with a lower number as a better score. The questions were developed by interviewing 20 patients with shoulder instability and then iteratively retesting the questions on different groups at different times. Construct validity has been further tested with prospective studies with comparison to other shoulder scores with moderate agreement. 
The WOSI or Oxford score are reliable and reproducible tools for the use in a modern study evaluating shoulder instability. 

Common Surgical Approaches of Glenohumeral Instability

Open Anterior Approach of Glenohumeral Instability

The skin incision varies depending on the procedure. If the surgery is mainly on the glenoid side, a very cosmetic incision is placed on the anterior axillary crease, which is identified with arm adduction, starting just distal to the coracoid process (Fig. 40-36A). If work will be done on the humeral side, the skin incision can be directed more laterally from the coracoid. After the skin incision and subcutaneous dissection, the interval between the anterior deltoid and the pectoralis major muscle is identified. This area, also referred to as the deltopectoral interval, is defined by the cephalic vein which must be dissected and retracted away from the surgical field (Fig. 40-36B). The cephalic drains the anterior part of the deltoid and therefore it is easier to take the vein laterally, however, the surgeon should limit the amount of retraction on the vein to prevent tearing. This interval is typically slightly medial to the skin incision. 
Figure 40-36
Anterior approach to the shoulder.
 
A: The incision extends from the coracoid to the axillary fold. B: The deltopectoral interval is identified and developed, taking the cephalic vein laterally with the deltoid. C: The conjoined tendon and subscapularis are identified. D: A subscapularis tenotomy is made vertically, separating the subscapularis tendon from the underlying capsule.
A: The incision extends from the coracoid to the axillary fold. B: The deltopectoral interval is identified and developed, taking the cephalic vein laterally with the deltoid. C: The conjoined tendon and subscapularis are identified. D: A subscapularis tenotomy is made vertically, separating the subscapularis tendon from the underlying capsule.
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Figure 40-36
Anterior approach to the shoulder.
A: The incision extends from the coracoid to the axillary fold. B: The deltopectoral interval is identified and developed, taking the cephalic vein laterally with the deltoid. C: The conjoined tendon and subscapularis are identified. D: A subscapularis tenotomy is made vertically, separating the subscapularis tendon from the underlying capsule.
A: The incision extends from the coracoid to the axillary fold. B: The deltopectoral interval is identified and developed, taking the cephalic vein laterally with the deltoid. C: The conjoined tendon and subscapularis are identified. D: A subscapularis tenotomy is made vertically, separating the subscapularis tendon from the underlying capsule.
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A self-retainer placed below the deltoid and pectoralis allows visualization of the underlying clavipectoral fascia which can be incised just at the lateral edge of the coracobrachialis muscle fibers (Fig. 40-36C). Bringing the arm into flexion and slight abduction relaxes the deltoid and can help with exposure. At this point, though some experienced surgeons place a self-retaining retractor beneath the conjoined tendon, we believe this is not advisable given the risk of musculocutaneous nerve injury. The musculocutaneous nerve enters on average 5 cm from the tip of the coracoid. However, in our experience, it can be as close as 1 cm.372 
A blunt handheld retractor, such as a Green retractor, can pull the conjoined tendon medially giving exposure to the subscapularis muscle and tendon. Some surgeons release part of the lateral conjoined for improved exposure, though we have no experience with this. Typically, there is a bursa overlying the muscle and tendon that needs to be excised. The axillary nerve is often easily palpable and visualized slightly medially and inferiorly at the subscapularis. It should be protected with a handheld retractor. 
Management of the subscapularis for exposure to the underlying capsule is arguably the most important aspect of the exposure. The overlying subscapularis muscle and tendon may be split in line with its fibers or it can be incised 1 cm medial to its insertion at the lesser tuberosity (Fig. 40-36D) and reflected medially. The key is defining the plane between the subscapularis and capsule medially, deep to the muscular part of the subscapularis because the tendon and capsule merge laterally. 
At this point, the capsule can be incised a number of ways depending on surgeon preference and the goal of the surgery. When performing an open capsulorrhaphy, we prefer a “T” incision with a horizontal incision at the center of the joint with a vertical incision medial and parallel to the glenoid rim. 

Open Posterior Approach of Glenohumeral Instability

The skin incision is placed just medial to the posterolateral corner of the acromion, extending to the axillary crease. Traditional approaches have released the deltoid muscle from its origin on the acromion. However, access can be achieved by splitting the deltoid which is easiest at the middle and posterior thirds, often identified by a fatty stripe. This split also typically starts at the posterolateral corner of the acromion to the upper border of the teres minor—approximately 10 cm (Fig. 40-37). The theoretical advantage of this modification is the preservation of strength and function of the posterior deltoid. 
Figure 40-37
The posterior approach to the shoulder.
 
After the skin incision, the deltoid muscle can be split along its fibers from the acromion to the upper border of the teres minor. Underlying rotator cuff tendons can then be split to gain access to the shoulder capsule and joint.
After the skin incision, the deltoid muscle can be split along its fibers from the acromion to the upper border of the teres minor. Underlying rotator cuff tendons can then be split to gain access to the shoulder capsule and joint.
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Figure 40-37
The posterior approach to the shoulder.
After the skin incision, the deltoid muscle can be split along its fibers from the acromion to the upper border of the teres minor. Underlying rotator cuff tendons can then be split to gain access to the shoulder capsule and joint.
After the skin incision, the deltoid muscle can be split along its fibers from the acromion to the upper border of the teres minor. Underlying rotator cuff tendons can then be split to gain access to the shoulder capsule and joint.
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Sometimes, in patients whose deltoid muscle contains significant bulk and resting tone, adequate exposure of the shoulder may not be possible by simply splitting the muscle. In these rare circumstances, the posterior deltoid is released from its origin on the acromion, and then reattached at the end of the procedure using bone tunnels. 
The infraspinatus is identified by its bipennate nature and its broad posterior insertion onto the greater tuberosity. The teres minor is inferior and has a more narrow insertion. 
Generally the infraspinatus tendon is lax, and can simply be retracted superiorly instead of releasing it. The teres minor muscle fibers are then retracted inferiorly to gain exposure to the posterior capsule. External rotation can help relax these muscles. Alternatively, there is a fat stripe between upper and lower portions of the teres that can be split, allowing exposure to the midpoint of the joint capsule. 
The posterior capsule is isolated from the musculature medially with the sweep of a finger or blunt instrument. Laterally, however, meticulous sharp dissection is required to separate the tendinous portion of the muscles from the capsule. 
If exposure is difficult, the infraspinatus muscle can be isolated with a Penrose drain placed for traction. The tendon can then be incised 0.5 cm from its insertion and reflected medially. Excessive medial reflection should be avoided to prevent injury to the suprascapular nerve. Care must be taken when handling the teres minor because the axillary nerve and the posterior humeral circumflex vessels lie just inferior in the quadrilateral space. 
Once the posterior capsule is isolated, it is incised to expose the joint. The capsulotomy incisions vary with each procedure and technique, as described below. 

Arthroscopic Approach and Portal Placement

The typical subcutaneous bony structures marked out on the skin prior to surgery include the scapular spine, acromion, clavicle, acromioclavicular joint, and coracoid process (Fig. 40-38). From these landmarks, initial portal placement can be defined. Although shoulder arthroscopy can be performed in either the lateral decubitus position or the beach chair position, arthroscopic portal placement is similar for the two different surgical approaches. Arthroscopic stabilization procedures typically utilize multiple intra-articular portals, including standard anterior and posterior portals, as well as accessory portals like the accessory superolateral portal. 
Figure 40-38
 
Anterior (A) and superior (B) views of the right shoulder, with the subcutaneous borders of the scapular spine, acromion, acromioclavicular joint, clavicle, and coracoid process outlined. The numbered Xs represent possible arthroscopic portal sites: 1, primary posterior; 2, posteroinferior; 3, supraspinatus or Neviaser; 4, lateral subacromial; 5, primary anterior; 6, anteromedial; 7, accessory superolateral; 8, anterior acromioclavicular.
Anterior (A) and superior (B) views of the right shoulder, with the subcutaneous borders of the scapular spine, acromion, acromioclavicular joint, clavicle, and coracoid process outlined. The numbered Xs represent possible arthroscopic portal sites: 1, primary posterior; 2, posteroinferior; 3, supraspinatus or Neviaser; 4, lateral subacromial; 5, primary anterior; 6, anteromedial; 7, accessory superolateral; 8, anterior acromioclavicular.
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Figure 40-38
Anterior (A) and superior (B) views of the right shoulder, with the subcutaneous borders of the scapular spine, acromion, acromioclavicular joint, clavicle, and coracoid process outlined. The numbered Xs represent possible arthroscopic portal sites: 1, primary posterior; 2, posteroinferior; 3, supraspinatus or Neviaser; 4, lateral subacromial; 5, primary anterior; 6, anteromedial; 7, accessory superolateral; 8, anterior acromioclavicular.
Anterior (A) and superior (B) views of the right shoulder, with the subcutaneous borders of the scapular spine, acromion, acromioclavicular joint, clavicle, and coracoid process outlined. The numbered Xs represent possible arthroscopic portal sites: 1, primary posterior; 2, posteroinferior; 3, supraspinatus or Neviaser; 4, lateral subacromial; 5, primary anterior; 6, anteromedial; 7, accessory superolateral; 8, anterior acromioclavicular.
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The primary posterior portal is defined by the natural soft spot that exists between the humeral head and glenoid posteriorly (Fig. 40-38)-–typically around 1 to 2 cm medial and 2 to 3 cm distal to the posterolateral corner of the acromion. 
The primary anterior portal is typically made next (Fig. 40-38). This portal enters the glenohumeral joint through the triangular space defined by the long head of the biceps tendon superiorly, the upper border of the subscapularis tendon inferiorly, and the anterosuperior glenoid and labrum medially (Fig. 40-39). The site and angle of entry for this portal on the skin is best determined with the use of a spinal needle. This provides confirmation that portal placement will allow appropriate access to all necessary structures before making the skin incision. The superior–inferior position of this portal will also vary, depending on its intended use. This portal should be placed just above the upper border of the subscapularis tendon, often called an anteromedial portal, to allow appropriate access to the anteroinferior labrum during arthroscopic labral repair. 
Figure 40-39
Arthroscopic view from the primary posterior portal in a right shoulder, showing the anterior triangular space through which the primary anterior portal is directed.
 
This space is defined by the long head of the biceps tendon (Bi) superiorly, the upper border of the subscapularis inferiorly (Ss), and the anterosuperior glenoid (G) and labrum (L) medially. The site and angle of entry for this portal is best determined with use of a spinal needle. H, humeral head.
This space is defined by the long head of the biceps tendon (Bi) superiorly, the upper border of the subscapularis inferiorly (Ss), and the anterosuperior glenoid (G) and labrum (L) medially. The site and angle of entry for this portal is best determined with use of a spinal needle. H, humeral head.
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Figure 40-39
Arthroscopic view from the primary posterior portal in a right shoulder, showing the anterior triangular space through which the primary anterior portal is directed.
This space is defined by the long head of the biceps tendon (Bi) superiorly, the upper border of the subscapularis inferiorly (Ss), and the anterosuperior glenoid (G) and labrum (L) medially. The site and angle of entry for this portal is best determined with use of a spinal needle. H, humeral head.
This space is defined by the long head of the biceps tendon (Bi) superiorly, the upper border of the subscapularis inferiorly (Ss), and the anterosuperior glenoid (G) and labrum (L) medially. The site and angle of entry for this portal is best determined with use of a spinal needle. H, humeral head.
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An anteroinferior portal has also been described, if needed, to allow for inferior enough anchor placement during arthroscopic repair of the anteroinferior labrum.61 The portal is made lower than the typical anterior portal, passing through the subscapularis tendon to access the 5 or 6 o’clock position on the glenoid. 
An accessory superolateral portal is frequently used for arthroscopic stabilization procedures, and is made through the rotator interval.61,188 This portal is commonly used for visualization of the anterior glenoid during anterior labral repair. 
The supraspinatus portal or Neviaser portal may occasionally be utilized for labral repairs, particularly repairs of the superior labrum.237 This portal is defined on the skin where the scapular spine meets the medial border of the acromion, just posterior to the acromioclavicular joint (Fig. 40-38). A spinal needle can be placed at this spot, passing through the supraspinatus muscle belly, and brought into the glenohumeral joint along the superior aspect of the glenoid and labrum. 
For posterior arthroscopic stabilization procedures like posterior labral repair, one or more accessory posterior portals may be utilized. An accessory posteroinferior portal, often called the 7 o’clock portal, can be made for inferior anchor placement during arthroscopic posterior labral repair.60 Typically the skin incision for this portal is several centimeters inferior and lateral to the standard posterior viewing portal (Fig. 40-38). For anchor placement along the posterosuperior glenoid, it may be necessary to make a portal of Wilmington.218 The skin incision for this portal is approximately 1 cm anterior and 1 cm lateral to the posterolateral corner of the acromion. 
If the subacromial space needs to be accessed, typically because of the presence of rotator cuff pathology, the primary posterior portal can be used to enter and visualize this space. Alternatively, a lateral portal is made approximately 2 to 3 cm distal to the lateral edge of the acromion, along the anterior aspect of the bone. 

Treatment Options for Glenohumeral Instability

Anterior Instability

As discussed above, anterior instability is the most common direction of glenohumeral instability, occurring most commonly from a traumatic injury in males less than 30 years of age. First-time dislocation events can typically be managed nonoperatively, with closed reduction followed by shoulder rehabilitation. The decision to proceed with surgical intervention usually arises from the development of recurrent instability. 
Because of the high risk of recurrence, the ideal treatment for young and active patients with an acute shoulder dislocation is debated. Some authors have recommended immediate surgical stabilization of the shoulder in specific high-risk patient groups,160,300,362 although others have found that surgical stabilization is necessary in only a minority of patients and recommend against immediate surgery.312 Ultimately, the decision to proceed with nonoperative versus operative management should be made on a case-by-case basis, based on the patient’s age, activity level, presenting history, and type and severity of pathology. 

Nonoperative and Closed Treatment

Indications/Contraindications
Acute Anterior Dislocations.
An acute anterior dislocation of the glenohumeral joint can be treated with closed reduction in almost all cases and should proceed as soon as possible. Ideally, closed reduction should be performed within the first several hours after the dislocation event, as the shoulder can become more difficult to reduce closed the longer it has been out. Shoulder dislocations that are greater than a day old may still be possible to close reduce, but the likelihood of success decreases and the risk of complications, such as fracture, increases. A dislocation that is more than a week old may have developed soft tissue contractures that no longer make close reduction possible. 
Chronic Anterior Dislocations.
If a patient has a chronic anterior dislocation (>3 to 6 weeks), closed reduction may no longer be possible and may be contraindicated because of the risk of fracture or neurovascular injury. In these situations, nonoperative management may be an appropriate choice. Chronic dislocations are seen most commonly in elderly patients or those whose comorbidities, especially dementia, may make them unaware that they have sustained a significant injury. These patients are often low demand, and may have reasonably good function and minimal pain in the affected shoulder. With a functional contralateral arm and limited demand, nonoperative management may be the best treatment option for these elderly patients and severe comorbidities or dementia. 
Recurrent Anterior Instability.
Nonoperative management for recurrent anterior instability may be considered in patients too medically ill to undergo an operation, those patients with no prior treatment, or in patients wishing to avoid surgery. The mainstay of nonoperative treatment has been physical therapy. Therapy is focused on strengthening the dynamic stabilizers of the shoulder; including the rotator cuff, deltoid, pectoralis major, and scapular stabilizing muscles; to provide stability for the compromised glenohumeral joint. However, there is no data we are aware of that supports the theoretical benefit of therapy (Table 40-3). 
 
Table 40-3
Anterior Instability
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Table 40-3
Anterior Instability
Nonoperative Treatment
Indications Relative Contraindications
First-time acute dislocation Irreducible first-time acute dislocation
Recurrent instability without prior treatment Recurrent instability failing nonoperative management
Recurrent atraumatic instability Open injuries
Chronic dislocation with good function and no pain
Patient medically unstable for surgery
Unstable epilepsy
Chronic dislocation with poor function and pain
X
Closed Reduction
Preoperative Planning.
Obtaining adequate muscle relaxation is essential to successfully reducing a shoulder dislocation in a closed fashion, regardless of the technique utilized. Some level of anesthesia is usually required to achieve muscle relaxation and pain control prior to reduction. However, some acute dislocations can be reduced without the use of medication if performed immediately after the injury before muscle spasm has developed. Intravenous analgesic and sedation agents are usually used, but require careful patient monitoring because of the possibility of respiratory depression from excessive sedation. Appropriate backup for airway protection should be available. This is usually possible in the emergency room setting, but if adequate respiratory support is not available, the reduction should be performed in the operating room with formal anesthesia. The used of formal anesthesia in the operating room may also be necessary if adequate muscle relaxation cannot be obtained without deeper levels of sedation. The surgeon should also be prepared for open reduction if closed reduction fails in the operating room, although this is very rare. 
Three randomized trials, along with other lower level studies, have compared the use of intravenous agents for analgesia and muscle relaxation to a intra-articular injection of lidocaine into the glenohumeral joint. Collectively, these studies have shown high rates of success with intra-articular lidocaine with fewer adverse events, a shorter hospital stay, and adequate pain relief53,66,209,222,251 (Table 40-4). 
 
Table 40-4
Closed Reduction of an Anterior Dislocation
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Table 40-4
Closed Reduction of an Anterior Dislocation
Preoperative Planning
  •  
    Adequate sedation and muscle relaxation
  •  
    Appropriate airway protection available
  •  
    Radiolucent table or bed
  •  
    Patient positioning in the room to allow for fluoroscopy
  •  
    Orthosis for arm immobilization should be available postreduction
X
Positioning.
Patient positioning is dependent on the particular closed reduction technique, as described below. The patient can be placed supine, either completely flat or in a beach-chair position, or prone. The use of a radiolucent table can be helpful to allow for easier use and positioning of fluoroscopy. Fluoroscopy should be positioned to obtain both AP and axillary views. This can be achieved by bringing the machine in from the opposite side of the bed or from the same side from a cephalad position. 
Techniques.
A simple traction–countertraction closed reduction technique, as described originally by Hippocrates, is used very commonly (Fig. 40-40).128,185 In the original method, reduction is performed by a single person, who provides countertraction by placing a foot against the chest wall, just inferior to the axilla, while pulling gentle traction on the arm. In most instances, assistance is available to allow this technique to be performed in a more elegant manner. The patient lies supine and countertraction is provided by a sheet wrapped around the waist of an assistant and around the upper thorax of the patient (Fig. 40-40). The surgeon can then stand on the side of the dislocated shoulder with a second sheet wrapped around his or her waist and around the forearm of the patient with the elbow flexed to 90 degrees. Against the assistant’s countertraction, slow and steady traction is applied to the patient’s arm with the second sheet to distract the humeral head away from the glenoid and disengage it from the glenoid rim. The surgeon can pull traction without the use of a sheet, but the sheet keeps the surgeon’s hands free to internally rotate, externally rotate, abduct, or adduct the patient’s arm, or provide direct pressure on the humeral head as needed to assist with “unlocking” the dislocation. 
Figure 40-40
Closed shoulder reduction using traction–countertraction.
 
The original Hippocratic method (A) uses gentle traction on the arm against countertraction provided by placing the foot on the chest wall. Care must be taken to avoid placing the foot in the axilla, as it can cause damage to neurovascular structures. With the help of an assistant, this technique can be performed using a sheet wrapped around the upper thorax to provide countertraction (B).
The original Hippocratic method (A) uses gentle traction on the arm against countertraction provided by placing the foot on the chest wall. Care must be taken to avoid placing the foot in the axilla, as it can cause damage to neurovascular structures. With the help of an assistant, this technique can be performed using a sheet wrapped around the upper thorax to provide countertraction (B).
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Figure 40-40
Closed shoulder reduction using traction–countertraction.
The original Hippocratic method (A) uses gentle traction on the arm against countertraction provided by placing the foot on the chest wall. Care must be taken to avoid placing the foot in the axilla, as it can cause damage to neurovascular structures. With the help of an assistant, this technique can be performed using a sheet wrapped around the upper thorax to provide countertraction (B).
The original Hippocratic method (A) uses gentle traction on the arm against countertraction provided by placing the foot on the chest wall. Care must be taken to avoid placing the foot in the axilla, as it can cause damage to neurovascular structures. With the help of an assistant, this technique can be performed using a sheet wrapped around the upper thorax to provide countertraction (B).
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The Stimson technique also utilizes slow, steady traction on the arm to achieve reduction.335 The patient is placed prone with the affected arm hanging free over a table, allowing the table to provide a stable base against which a gentle downward traction is placed on the arm (Fig. 40-41). Traction can be applied manually or by attaching weights to the wrist. Usually 5 lb is sufficient for most patients, but more may be needed depending on patient size. Slow, steady traction provided by the attached weights results in fatigue and relaxation of the shoulder musculature that disengages the humeral head and reduces the shoulder after traction is released. This method usually takes up to 15 to 20 minutes to produce its effect; however, the patient should be monitored closely to avoid a prolonged period of time in this position that could result in traction injury to a nerve. 
Figure 40-41
The Stimson technique for closed shoulder reduction.
 
With the patient lying prone, weight is hung from the wrist to provide traction to the shoulder joint. This steady traction leads to fatigue and relaxation in the shoulder musculature, resulting in joint reduction.
With the patient lying prone, weight is hung from the wrist to provide traction to the shoulder joint. This steady traction leads to fatigue and relaxation in the shoulder musculature, resulting in joint reduction.
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Figure 40-41
The Stimson technique for closed shoulder reduction.
With the patient lying prone, weight is hung from the wrist to provide traction to the shoulder joint. This steady traction leads to fatigue and relaxation in the shoulder musculature, resulting in joint reduction.
With the patient lying prone, weight is hung from the wrist to provide traction to the shoulder joint. This steady traction leads to fatigue and relaxation in the shoulder musculature, resulting in joint reduction.
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The Milch technique can also be utilized to close reduce an anterior dislocation, but relies on shoulder position more so than traction.220 The maneuver can be performed with the patient in either a supine or prone position. The arm is slowly abducted while stabilizing the humeral head with the opposite hand. The shoulder is then slowly externally rotated, causing the humeral head to spontaneously reduce when the shoulder has reached approximately 90 degrees of abduction and 90 degrees of external rotation. The opposite hand that is stabilizing the humeral head can also be used to provide posterior pressure to help guide the humeral head back into the joint. This method has been reported to have a high rate of success with minimal complications and can be performed without premedication.85,247 
A recent trial compared the success of the Milch versus the Stimson techniques for reduction in nonsedated patients. The authors found significantly better success rates and time to reduction for the Milch technique. Importantly, earlier reductions and low levels of pain at presentation were predictive of greater success.4 
Postoperative Management.
Once closed reduction is complete, anatomic reduction of the glenohumeral joint must be confirmed with fluoroscopy or plain radiographs. Grashey and axillary views should be obtained and will also demonstrate any associated fractures. Postreduction documentation of the neurovascular status of the arm should also be performed and compared to the pre-reduction examination for any changes. 
The arm is immobilized for a period of time following closed reduction to avoid recurrent instability. There has been conflicting information on the length, type, and position of immobilization required for the shoulder. Earlier studies have reported decreased rates of recurrent instability in patients whose shoulders were immobilized for greater than 3 weeks.164,179,336 In contrast, several more recent studies have not reported an association between the duration of immobilization and the development of recurrent instability.132,133,262 A recent systematic review of Level I and II studies evaluating the length of immobilization time following a primary anterior shoulder dislocation found no significant difference in rate of recurrent instability in patients younger than 30 years of age immobilized for 1 week or less (41%) versus 3 weeks or longer (37%).262 
The position of immobilization has received significant attention recently. In an initial MRI study, Itoi et al. demonstrated that the position of the anterior labrum after closed reduction of a traumatic anterior shoulder dislocation was more anatomic when the arm was positioned in slight external rotation.153 In a subsequent randomized controlled trial, the authors demonstrated a significantly lower rate of recurrent instability at minimum 2-year follow-up (26% vs. 42%) for first time traumatic anterior dislocations immobilized in external rotation for 3 weeks compared to those immobilized in internal rotation.146 However, other authors have not shown an advantage for immobilization in external rotation. Liavaag et al. performed a randomized controlled trial comparing immobilization for 3 weeks in external versus internal rotation in patients with first time traumatic anterior dislocations.197 At minimum 2-year follow-up, there was no significant difference in the rate of recurrent instability between groups (30.8% for external rotation vs. 24.7% for internal rotation). It appears that immobilization in external rotation does not clearly show a benefit over a traditional sling. 
To restore function as promptly as possible, a brief period of immobilization should be followed by mobilization and rehabilitation. Shoulder rehabilitation is focused both on regaining range of motion and strengthening of the shoulder. The dynamic stabilizers of the shoulder; including the rotator cuff, deltoid, pectoralis major, and scapular stabilizing muscles are strengthened to provide stability for the compromised glenohumeral joint.46,100,185 
Pitfalls and Solutions (Table 40-5)
 
Table 40-5
Closed Reduction of an Anterior Dislocation
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Table 40-5
Closed Reduction of an Anterior Dislocation
Potential Pitfalls and Solutions
Pitfall Solutions
Displacement of fracture ORIF
Hemiarthroplasty or reverse total shoulder arthroplasty
Acute instability or irreducibility Open or arthroscopic procedure discussed below
Recurrent instability Open or arthroscopic procedure discussed below
X
Outcomes.
The most common complication after a successful closed reduction is the development of recurrent instability. As noted above, risk factors have been identified for the development of recurrent instability, such as age, gender, activity level, compliance, and associated injuries (rotator cuff tears, fractures, bone defects, etc.), with the risk of recurrent anterior instability highest among highly active, young male patients. 

Operative Treatment of Anterior Instability

Indications/Contraindications
Acute Anterior Dislocatons.
The indications for surgical intervention for an acute anterior dislocation include an irreducible or unstable injury, dislocations associated with a displaced proximal humerus fracture, and open injuries. Irreducible or unstable injuries may be caused by a bony cause (proximal humerus fracture, glenoid fracture, large Hill–Sachs defect), a large rotator cuff tear, or soft tissue interposition in the glenohumeral joint by torn rotator cuff tissue or the long head of the biceps tendon.40,57,112,144,341 
Chronic Anterior Dislocations.
As discussed above, nonoperative management may be indicated with certain chronic dislocations in elderly patients if they are demented, too sick for surgery, or if the shoulder has good function and no pain. Otherwise, if the patient is stable for surgery and poor function and pain are present, surgery is indicated. The choice of procedure, as discussed below, depends on the bone and soft tissue injuries that are present. If large Hill–Sachs and/or glenoid bone defects are present because of a long-standing dislocation, these may require reconstruction with bone grafts or treatment with shoulder arthroplasty.98 
Recurrent Anterior Instability.
Surgical treatment of recurrent anterior instability is indicated when nonoperative management has failed. Stabilization of the shoulder may be performed arthroscopically, or through an open anterior approach, with or without bony reconstruction (humeral and/or glenoid), as discussed below. Arthroscopic procedures have the benefit of evaluating the entire glenohumeral joint prior to treatment, which may uncover additional pathology that requires surgical repair, such as posterior or superior labral tears293 (Table 40-6). 
 
Table 40-6
Anterior Instability
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Table 40-6
Anterior Instability
Operative Treatment
Indications Contraindications
Irreducible or unstable first time acute dislocation Reducible, first time acute dislocation
Recurrent instability failing nonoperative management Recurrent instability without prior treatment
Open injuries Patient medically unstable for surgery
Chronic dislocation with poor function and pain Chronic dislocation with good function and no pain
Dislocation associated with displaced proximal humerus fracture Unstable epilepsy
X
Open Reduction of an Anterior Dislocation.
If a stable closed reduction is unsuccessful, open reduction with or without additional procedures must be performed. In the acute setting, open reduction may be all that is needed to stabilize the joint; however, other soft tissue surgery may be required, such as capsulolabral repair or rotator cuff repair, if tears are present. Soft tissue interposition in the glenohumeral joint, either from torn rotator cuff tissue or the long head of the biceps tendon, should also be addressed if present with repair or tenodesis, respectively.40,57,112,144,341 
In the chronic setting, significant bone loss is more likely to be present in the humeral head and/or glenoid and additional surgery may be needed to address the bone defects, as discussed below.98 
Preoperative Planning (Table 40-7)
 
Table 40-7
Open Anterior Reduction of an Anterior Dislocation
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Table 40-7
Open Anterior Reduction of an Anterior Dislocation
Preoperative Planning
  •  
    Radiolucent or beach-chair table
  •  
    Patient positioning in the room to allow for fluoroscopy
  •  
    Standard open shoulder instruments
  •  
    Additional equipment, as needed, for potential bony or soft tissue repairs (suture anchors, small fragment set, etc.)
  •  
    Orthosis for arm immobilization should be available postreduction
X
Positioning.
Our standard setup is the beach-chair position with an articulated arm holder. A supine position may also be used. Fluoroscopy should be positioned to obtain both AP and axillary views as noted above. 
Surgical Approach and Technique.
A standard deltopectoral approach (Fig. 40-36) is used with the long head of the biceps tendon as a guide to find the lesser tuberosity and the rotator interval. In situations requiring no additional repairs, the biceps tendon can be followed proximally and the rotator interval released to gain access to the glenohumeral joint. A finger can be placed through the interval and into the joint to help manually pull the humeral head laterally with traction to disimpact the head. Sometimes a bone hook can be utilized to help pull lateral traction, but care should be taken to not damage the cartilage of the humeral head. The shoulder can be internally or externally rotated as needed to assist with unlocking the humeral head. Once the humeral head is disimpacted, it can be brought posteriorly with digital pressure to help reduce the shoulder. Stability of the reduction should be tested in abduction and by bringing the arm into external rotation. Positioning of the arm postoperatively, as with closed reductions, is determined by the assessment of intraoperative stability. Most shoulders are stable after reduction; however, if gross instability is present, an open capsular repair should be performed as described below. 
If reduction cannot be performed through the rotator interval alone, then the subscapularis tendon should be taken down to completely access the glenohumeral joint as discussed earlier in the chapter. If a significant humeral head defect is present following reduction, humeral head disimpaction may be considered. A disimpaction procedure is an option if the humeral head bone stock is good, the impacted cartilage can be salvaged, the defect is <40%, and the dislocation is less than 3 weeks old.9,279 Chronic dislocations suffer from disuse osteopenia. The technique involves elevating an impaction fracture to restore humeral head anatomy. A cortical window is created opposite the defect, through which bone tamps can be inserted to disimpact the fracture in a retrograde fashion.165 It may also be performed percutaneously.289 Once elevated, the humeral head void is filled with cancellous allograft (our preferred choice), iliac crest, or another bone substitute product.165,216,289 
Postoperative Management.
The postoperative management is the same as with closed reduction. However, if the subscapularis tendon is taken down as part of the surgery, rehabilitation is significantly slower to allow for healing of the tendon with no external rotation beyond neutral for 6 weeks. 
Pitfalls and Solutions (Table 40-8)
 
Table 40-8
Open Anterior Reduction of an Anterior Dislocation
View Large
Table 40-8
Open Anterior Reduction of an Anterior Dislocation
Potential Pitfalls and Solutions
Pitfalls Solutions
Displacement of fracture ORIF
Hemiarthroplasty or reverse total shoulder arthroplasty
Irreducible dislocation Subscapularis takedown for complete glenohumeral joint access
Intraoperative instability Bony or soft tissue repair as indicated (described below)
Axillary nerve injury Direct repair
Observation
X
Outcomes.
There is limited data on the outcomes of simple open reduction of an anterior dislocation.112 Often, whether the dislocation is acute or chronic, associated pathology is present that requires surgical intervention in addition to the open reduction. 
Humeral head disimpaction in the setting of anterior shoulder instability has only been reported in a handful of cases, including one case of chronic dislocation.216,289 Re et al. evaluated the results of four patients who underwent humeral head disimpaction as part of an open instability procedure.289 No complications or recurrent instability was noted at greater than 1-year follow-up. Three patients also underwent open anterior capsulolabral reconstruction and the fourth underwent a Latarjet procedure. 
Open Anterior Procedures for Chronic Anterior Dislocations.
As discussed above, significant bone loss may be present in the humeral head and/or glenoid that require additional surgery following open reduction in the setting of a chronic dislocation. Soft tissue injuries, including rotator cuff tears and labral tears, may also require repair in this setting to stabilize the joint. Anterior glenoid defects of 25% or more should be addressed with a bone reconstruction procedure (Latarjet procedure, iliac crest bone graft, allograft bone graft), whereas Hill–Sachs defects involving 25% or more of the humeral head may be addressed with allograft reconstruction or partial resurfacing.9,224,276,279 Shoulder arthroplasty may be necessary for even larger defects, especially in older patients with Hill–Sachs defects involving 40% to 45% or more of the humeral head an indication for complete humeral head replacement.9,80,274,279 
Preoperative Planning (Table 40-9)
 
Table 40-9
Open Anterior Procedures for Chronic Anterior Dislocations
Preoperative Planning
  •  
    Beach-chair table with pneumatic arm holder
  •  
    Fluoroscopy may be needed to check direction and length of screws or confirm joint reduction
  •  
    Standard open shoulder instruments
  •  
    Additional equipment, as needed, for potential bony or soft tissue procedures, or shoulder arthroplasty (suture anchors, small fragment set, etc.)
    •  
      Fresh frozen allograft for glenoid defect
    •  
      Size-matched fresh frozen allograft for humeral head defect
    •  
      Screws for fixation of glenoid and/or humeral head graft
    •  
      Arthroplasty equipment (partial resurfacing, standard and/or reverse replacement sets)
  •  
    Suture anchors for rotator cuff or labral repair
  •  
    Orthosis for arm immobilization should be placed after surgery
X
Positioning.
The beach-chair position is used as described above. 
Surgical Approach.
A standard deltopectoral approach is used for these procedures. 
Technique.
The techniques for reconstruction of the anterior capsulolabral structures, or for reconstruction of bony defects of the glenoid and humeral head are the same as those utilized in the management of recurrent anterior instability and are described in the sections below. Most commonly, a subscapularis tenotomy is performed to access the glenohumeral joint for these procedures. In contrast to a reduced joint, however, significant adhesions and soft tissue contractures may be present in the setting of a chronic, unreduced dislocation. The soft tissue plane between the conjoined tendon and the subscapularis tendon, for example, may be scarred together because of the anteriorly dislocated humeral head. Careful dissection is necessary in developing this plane to avoid neurovascular injury. When the glenohumeral joint is exposed, the chronic dislocation must first be unlocked and mobilized to allow for joint reduction and the necessary soft tissue or bony reconstructions. This may require extensive capsular releases around the joint, particularly posteriorly, where the capsule may be significantly contracted in a chronic anterior dislocation. In addition, the long head of the biceps tendon is often pathologic or limits visualization of the joint and therefore we typically excise the intra-articular portion and tenodese the remainder to the pectoralis major tendon with nonabsorable suture. 
Arthroplasty.
As noted above, shoulder arthroplasty may be necessary for larger humeral head defects, or if advanced degenerative changes are present.9,80,274,279 Hemiarthroplasty is usually performed in younger patients below the age of 50 and patients with good glenoid cartilage. Total shoulder arthroplasty is indicated in older patients with significant glenoid degenerative changes. In the elderly patient, reverse total shoulder arthroplasty may be necessary if the rotator cuff is deficient, or if there is concern for persistent instability with a standard shoulder replacement. 
Key technical considerations in arthroplasty include management of the subscapularis and version of the humeral component. Both subscapularis peel and lesser tuberosity osteotomy are acceptable options; however, a robust repair is critical to prevent further instability. The prosthesis version should match the patients’ anatomical version which varies dramatically with an average of 19 degrees of retroversion.296 Attention should be paid to not overly anteroverting the component, which is the natural tendency because of, sometimes, inadequate exposure. 
Postoperative Management.
For bone reconstruction and arthroplasty procedures, the patient’s shoulder is protected in an orthosis for 6 weeks with no active shoulder use during this time. At 6 weeks, active shoulder use is allowed and range of motion stretching is begun. Strengthening is started 3 months after surgery. 
Pitfalls and Solutions (Table 40-10)
 
Table 40-10
Open Anterior Procedures for Chronic Anterior Dislocations
Potential Pitfalls and Solutions
Pitfalls Solutions
Axillary nerve injury Direct repair
Observation
Osteopenic head or significant degenerative changes Consider arthroplasty
Pull-out of transosseous sutures during subscapularis repair Drill through the bicipital groove
Fracture of lesser tuberosity osteotomy Use small screw (2.0 or 2.7 mm)
Consider anchors or transosseous suture
X
Outcomes.
There is limited data on the outcomes of surgical treatment of chronic anterior shoulder dislocations. Rouhani and Navali reported on eight cases of open reduction with anterior capsulolabral repair for chronic anterior dislocation.305 Mean follow-up was 1 year, with one fair, three good, and four excellent results, and a mean Rowe and Zarin’s score of 86. Two patients had persistent anterior subluxation of the humeral head. Goga reviewed a series of 10 patients that underwent coracoid transfer to the anterior glenoid and temporary acromiohumeral K-wire fixation (4 weeks) for treatment of a chronic anterior dislocation.101 Minimum follow-up was 2 years, with two fair, five good, and three excellent results, and no recurrent dislocations. Pin site infections occurred in 8/10 patients, but resolved with pin removal. Finally, Flatow et al.80 reviewed a series of 10 patients who underwent surgery for a chronic anterior dislocation. One patient underwent coracoid transfer for an anterior glenoid defect, but had persistent anterior subluxation and underwent a revision soft tissue reconstruction to stabilize the shoulder. The other nine patients underwent shoulder arthroplasty (one hemiarthroplasty, eight total shoulder arthroplasties). Humeral component retroversion was increased as needed for stability, and three cases required anterior glenoid bone grafting to support the glenoid component. The hemiarthroplasty was lost to follow-up, whereas mean follow-up was 3.9 years in the other cases. There were four satisfactory and four excellent results, and no recurrent dislocations. 
Open Soft Tissue Procedures for Recurrent Anterior Instability.
Open anterior shoulder stabilization consisting of a capsulolabral (Bankart) repair has traditionally been considered the “gold standard” for surgical treatment of recurrent anterior instability, with many studies reporting good-to-excellent outcomes in the vast majority of patients.20,75,137,157,159,196,229,258,273,295,291,364 However, with the increased use of arthroscopic techniques and the continual development of arthroscopic instrumentation and suture anchors, outcomes of arthroscopic capsulolabral (Bankart) repair have been reported to be equivalent to the open procedure in selected patients.7,38,75,163,173,203,265,283,332,342350 Therefore, provided that the surgery is performed with adequate expertise, the choice between open and arthroscopic capsulolabral repair does not appear to significantly affect the overall outcome. 
Situations where an open technique may be preferred include revision surgery or other cases where anatomy is altered or deformity is present.223 Repair of a humeral avulsion of glenohumeral ligaments (HAGL lesion) may also require open repair.42,93,367 Importantly, patient selection for open versus arthroscopic repair is critical to outcomes. Balg et al. has created an instability severity index score which reliably identifies patients who have a high risk of recurrent instability after arthroscopic management. The risk factors include: Patients under the age of 20 (2 points); involvement in contact sports or those with forced overhead activity (1 point); shoulder hyperlaxity (1 point); a Hill–Sachs lesion present on the AP radiograph in external rotation (2 points); and loss of the sclerotic inferior glenoid contour (2 points).14 A score of 6 points or less predicted a recurrence risk after arthroscopic repair of 10%. Patients with more than 6 points had a recurrence risk of 70%. 
Preoperative Planning (Table 40-11)
 
Table 40-11
Open Anterior Soft Tissue Repair
View Large
Table 40-11
Open Anterior Soft Tissue Repair
Preoperative Planning
  •  
    Beach-chair table with pneumatic arm holder
  •  
    Fluoroscopy is not needed
  •  
    Standard open shoulder instruments
  •  
    Suture anchors for labral or capsular repair, as needed
  •  
    Orthosis for arm immobilization should be placed after surgery
X
Positioning.
The beach-chair position is used as described above. 
Surgical Approach.
A standard deltopectoral approach is used for the procedure. 
Technique.
Open Anterior Capsulolabral (Bankart) Repair.
Capsulolabral repair can be performed with a subscapularis tenotomy or through a subscapularis split, as described above. The capsule is then exposed and must be incised to access the glenohumeral joint and torn labrum. This can be performed in several ways depending on surgeon preference. A single transverse incision can be made in line with the subscapularis division, or a vertical incision can be combined with the transverse incision to create a “T”-shaped capsulotomy with superior and inferior flaps (Fig. 40-42). The vertical incision can be placed laterally near the humeral neck or medially along the glenoid rim. Tag sutures should be placed through the split superior and inferior capsule with either technique. 
Figure 40-42
“T”-shaped capsulotomy with superior and inferior flaps for glenohumeral joint exposure.
 
The vertical incision can be placed laterally near the humeral neck or medially along the glenoid rim.
The vertical incision can be placed laterally near the humeral neck or medially along the glenoid rim.
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Figure 40-42
“T”-shaped capsulotomy with superior and inferior flaps for glenohumeral joint exposure.
The vertical incision can be placed laterally near the humeral neck or medially along the glenoid rim.
The vertical incision can be placed laterally near the humeral neck or medially along the glenoid rim.
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X
A humeral head retractor, such as a Fukuda retractor, is placed between the humeral head and posterior rim of the glenoid to displace the humeral head posteriorly. One or two single-prong or multi-prong glenoid retractors are placed along the anterior glenoid neck to allow for adequate medial exposure. The detached labrum is then elevated from the glenoid neck if required, to mobilize the tissue. The torn labrum is typically healed in an inferomedial position and must be adequately freed up to restore the tissue to its original anatomic location. The glenoid neck and rim are next abraded with a rasp or high-speed burr to healthy, bleeding bone to establish a healing bed for the labral repair. 
Labral repair is then performed with suture anchors, or bone tunnels. Three or four suture anchors are typically needed to span the 3 o’clock-to-6 o’clock (or 9 to 6 on a left shoulder) position along the anteroinferior glenoid (Fig. 40-43). Specifically, the anchors should be placed on the face on the glenoid and not too anterior. Heavy, #2 nonabsorbable sutures are passed through the torn labrum and capsuloligamentous tissue for labral repair and capsulorrhaphy. If a small, avulsion-type glenoid rim fragment is also present, such as in a bony Bankart injury, this can also be incorporated with the torn soft tissue into the repair. The suture is typically passed through the tissue inferior to the anchor, or around it if a bony tunnel is used, both to re-establish the torn labrum along its anatomic location and to perform the desired capsulorrhaphy. The degree of capsular laxity noted intraoperatively dictates the amount of capsular shift that is performed. The capsule should not be overtightened to avoid stiffness of the glenohumeral joint, which can lead to increased joint contact forces and restriction of motion.351 The sutures should be tied off of the joint surface, along the capsule, to prevent the knots from lying within the joint and causing mechanical symptoms. The arm is usually positioned in approximately 30 degrees of abduction and external rotation to avoid overtightening the repair. 
Figure 40-43
Drill hole for suture anchor placement in open Bankart repair.
 
Holes should be placed right at the anterior glenoid articular margin.
Holes should be placed right at the anterior glenoid articular margin.
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Figure 40-43
Drill hole for suture anchor placement in open Bankart repair.
Holes should be placed right at the anterior glenoid articular margin.
Holes should be placed right at the anterior glenoid articular margin.
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X
The sutures are not cut after being tied, so that the limbs can be used to imbricate the superior flap of the split capsule to the repair site. The superior flap is shifted inferiorly to overlap with the inferior flap that was already shifted superiorly and tied down as a part of the Bankart repair (Fig. 40-44). The amount that the superior flap is shifted and the location the sutures are passed through and tied down on this flap are dictated by the degree of capsular laxity that is present. 
Figure 40-44
Capsular closure with open Bankart repair.
 
The superior flap is shifted inferiorly to overlap with the inferior flap that was already shifted superiorly and tied down as a part of the Bankart repair. The amount that the superior flap is shifted and the location the sutures are passed through and tied down on this flap are dictated by the degree of capsular laxity that is present.
The superior flap is shifted inferiorly to overlap with the inferior flap that was already shifted superiorly and tied down as a part of the Bankart repair. The amount that the superior flap is shifted and the location the sutures are passed through and tied down on this flap are dictated by the degree of capsular laxity that is present.
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Figure 40-44
Capsular closure with open Bankart repair.
The superior flap is shifted inferiorly to overlap with the inferior flap that was already shifted superiorly and tied down as a part of the Bankart repair. The amount that the superior flap is shifted and the location the sutures are passed through and tied down on this flap are dictated by the degree of capsular laxity that is present.
The superior flap is shifted inferiorly to overlap with the inferior flap that was already shifted superiorly and tied down as a part of the Bankart repair. The amount that the superior flap is shifted and the location the sutures are passed through and tied down on this flap are dictated by the degree of capsular laxity that is present.
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X
After capsulolabral repair is complete, the subscapularis is closed. If a tenotomy is performed, the tendon can be repaired back to the lateral stump with interrupted, heavy, #2 nonabsorbable sutures. A subscapularis split can be closed with interrupted #0 or #1 absorbable sutures. 
Open Repair of HAGL Lesion.
If a HAGL lesion is noted at the time of open labral repair, this must also be addressed. The lesion is typically found in the inferior pouch of the shoulder, between the 6 o’clock and 8 o’clock position on the humeral neck.8,36,93 The injury may be exposed using a subscapularis tenotomy or a mini-open technique in which some or all of the subscapularis tendon is preserved.8,24,93 After preparing a healthy, bleeding bone bed, the avulsed glenohumeral ligament is repaired back to its attachment site with suture anchors or drill holes through bone. 
Postoperative Management.
The patient’s shoulder is protected in an abduction splint for 6 weeks with no active shoulder use during this time. Passive range-of-motion exercises, including forward flexion and external rotation stretching, can be started within the first 6 weeks of surgery based on surgeon preference. At 6 weeks, active shoulder use is allowed and range of motion stretching is advanced to active exercises in all planes. Strengthening is started 3 months after surgery, with a return to contact activities at 5 to 6 months postoperatively. 
Pitfalls and Solutions (Table 40-12)
 
Table 40-12
Open Anterior Soft Tissue Repair
View Large
Table 40-12
Open Anterior Soft Tissue Repair
Potential Pitfalls and Solutions
Pitfalls Solutions
Axillary nerve injury Avoid being too inferior in the surgical approach
Avoid excessive humeral head distraction
Inadequate shift of associated capsular laxity Intraoperative assessment of shoulder range-of-motion after repair
Excessive capsular shift Appropriate arm position during repair (approximately 30 degrees of abduction and external rotation)
Intraoperative assessment of shoulder range-of-motion after repair
Unrecognized HAGL lesion HAGL repair, open or arthroscopic
Unrecognized anterior glenoid bone loss Open bony procedure (Bristow–Latarjet, auto- or allograft)
Fixation failure Minimum of three suture anchors for anteroinferior repair or tunnels through bony
Firm placement of suture anchors in subchondral bone, seated below articular margin
Improper anchor placement Placement of anchors on the face of the glenoid and not too anterior
Placement of anchors between 3 and 6 o’clock (right). Avoid superior anchors
X
Outcomes
Open Anterior Capsulolabral (Bankart) Repair.
Using the suture anchor method, good-to-excellent results have been reported in 88% to 94% of patients, with recurrent dislocation rates of 0% to 9.7% at short- to midterm follow-up.20,75,159,196,273,295 Even in athletes with high functional demands, the open Bankart procedure has been associated with good-to-excellent results in 92% to 97% of patients, with recurrent instability rates of 0% to 4%, and return to preinjury level of competition in 68% to 89% of patients.157,229,258 
In a long-term follow-up study, Pelet et al. evaluated 30 patients at a mean of 29 years after open Bankart repair using a bone tunnel technique.264 Recurrent dislocation occurred in three patients (10%), with one undergoing a revision open stabilization. Radiographic evidence of glenohumeral arthritis was present in 40% of patients, with five patients (16.6%) undergoing total shoulder arthroplasty at a mean of 26.6 years after Bankart repair because of symptomatic arthritis. Of the remaining patients, there was 1 poor, 4 fair, and 20 good results. Mean loss of shoulder external rotation was 24 degrees, and mean loss of internal rotation was 19 degrees. Outcome scores (Constant, Rowe modified, ASES) in the operative shoulder were significantly lower than the contralateral side. All patients said they would recommend the surgery.264 
Open Repair of HAGL Lesions.
Data on open repair of HAGL lesions has been limited to small studies or case reports.8,24,36 Arciero and Mazzocca reported no cases of recurrent instability in eight patients who underwent mini-open repair, whereas Bhatia et al. also reported no episodes of recurrent instability with a mini-open technique.8,24 
Arthroscopic Soft Tissue Procedures for Recurrent Anterior Instability.
Recent data has demonstrated that, for most patients, there are equivalent outcomes between arthroscopic and open capsulolabral (Bankart) repair.7,38,75,163,173,203,265,283,332,342,350,375 Reported complication rates may also be lower with the arthroscopic technique.255 These findings, in combination with the increased use and development of arthroscopic methods, have led to a national trend toward arthroscopic shoulder stabilization, with the use of open capsulolabral repair declining.255 Importantly, a certain group of high-risk patients may not benefit from arthroscopic repair and require an open procedure. Balg and Boileau14 identified these risk factors in their instability severity score (discussed above). 
Arthroscopic treatment of other instability-related lesions may also be performed with or without Bankart repair, if indicated. HAGL lesion may be amenable to arthroscopic suture anchor repair,42,93,367 and arthroscopic remplissage can also be considered. Remplissage is the term used to describe arthroscopic posterior capsulodesis and infraspinatus tenodesis, in which the posterior capsule and infraspinatus are anchored into the surface of a Hill–Sachs defect to prevent engagement of the lesion.65,182,279,284 Although the indication for the procedure is still evolving, it is often performed in the presence of a moderate to large Hill–Sachs defect associated with anterior glenoid bone loss that is not large enough for an open bony procedure (<25%).9,279 
Preoperative Planning (Table 40-13)
 
Table 40-13
Arthroscopic Soft Tissue Repair
View Large
Table 40-13
Arthroscopic Soft Tissue Repair
Preoperative Planning
  •  
    Beach-chair table with pneumatic arm holder, or lateral decubitus position with arm traction
  •  
    Fluoroscopy is not needed
  •  
    Standard arthroscopic shoulder instruments; 5 and 8 mm cannulas
  •  
    Suture anchors for labral or capsular repair
  •  
    Orthosis for arm immobilization should be placed after surgery
X
Positioning.
The beach-chair or lateral decubitus position is used as described above. 
Surgical Approach.
The standard arthroscopic technique describe above is utilized. 
Technique
Arthroscopic Anterior Capsulolabral (Bankart) Repairs.
After initial evaluation of the glenohumeral joint through the posterior portal to define the tear, an anterior portal is established just above the upper border of the subscapularis tendon. This portal is utilized for instrumentation and anchor placement during labral repair, and should be made low enough to provide complete access to the anteroinferior labrum. We prefer to visualize from an anterior position during the procedure; therefore, an accessory superolateral portal is next established through the rotator interval and the arthroscope is placed in this portal with the use of switching sticks. 
Arthroscopic labral repair utilizes the same steps as the open technique. The detached labrum is first elevated from the glenoid neck to mobilize the tissue. This can be performed with an arthroscopic tissue elevator and shaver, passed through the anterior portal. The glenoid neck and rim are next abraded with an arthroscopic rasp or burr to healthy, bleeding bone to establish a healing bed for the labral repair. Suture anchors are then sequentially placed through the anterior portal along the anterior glenoid articular margin. As with the open technique, three or four anchors are needed to span the 3 o’clock-to-6 o’clock position along the anteroinferior glenoid (Fig. 40-45). Typically, the most inferior anchor is placed first at the 6 o’clock position and the suture from this anchor is passed and tied down. The same steps are then repeated with the other anchors as they are placed, moving superiorly up the anterior glenoid rim. Suture passage is performed with a shuttle-relay device passed through the anterior portal. The torn labrum and capsule are captured with this device, and the posterior portal can be used to grab the wire or suture from the device to shuttle the suture from the anchor back through the captured tissue. As with the open technique, care is taken to pass the suture through tissue inferior to the anchor site, both to re-establish the torn labrum along its anatomic location and to perform the desired capsulorrhaphy. If a small glenoid rim fragment is also present, such as in a bony Bankart injury, this can also be incorporated with the torn soft tissue into the repair. The degree of capsular laxity noted intraoperatively dictates the amount of capsular shift that is performed, but typically less capsular tissue is shifted as the suture anchors are placed more superiorly. The sutures should again be tied off of the joint surface, along the capsule, to prevent the knots from lying within the joint and causing mechanical symptoms. 
Figure 40-45
Intraoperative images of arthroscopic Bankart repair.
 
A: Diagnostic arthroscopy demonstrates the torn anteroinferior capsulolabral tissue (arrow). B: The torn labrum is reattached to the glenoid rim using suture anchors, with the initial anchors placed inferiorly. C: Completed Bankart repair.
A: Diagnostic arthroscopy demonstrates the torn anteroinferior capsulolabral tissue (arrow). B: The torn labrum is reattached to the glenoid rim using suture anchors, with the initial anchors placed inferiorly. C: Completed Bankart repair.
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Figure 40-45
Intraoperative images of arthroscopic Bankart repair.
A: Diagnostic arthroscopy demonstrates the torn anteroinferior capsulolabral tissue (arrow). B: The torn labrum is reattached to the glenoid rim using suture anchors, with the initial anchors placed inferiorly. C: Completed Bankart repair.
A: Diagnostic arthroscopy demonstrates the torn anteroinferior capsulolabral tissue (arrow). B: The torn labrum is reattached to the glenoid rim using suture anchors, with the initial anchors placed inferiorly. C: Completed Bankart repair.
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X
Newer, knotless anchors are now also being used in arthroscopic labral repair. With these anchors, a free heavy, nonabsorbable suture is typically first passed through the torn capsule and labrum using standard techniques and then incorporated into the knotless anchor while the anchor is being placed. 
Arthroscopic Repair of HAGL Lesions.
If a HAGL lesion is noted at the time of arthroscopy, it may also be possible to address with arthroscopic suture anchor repair. Accessory portals, such as an anteroinferior or posteroinferior portal, may be necessary to obtain the proper angle of anchor insertion.23 Suture passage through the avulsed glenohumeral ligament is also performed using a shuttle-relay device. In general, however, an open repair is recommended if a HAGL lesion is diagnosed preoperatively. 
Remplissage.
Remplissage is typically performed with the arthroscope in one of the anterior portals. As with the other arthroscopic repairs, suture anchors are utilized for the technique. One or two anchors are placed through a posterior portal, either with a cannula or percutaneously, into the Hill–Sachs lesion. This portal should be placed to obtain the proper angle of anchor insertion. Suture passage through the posterior capsule and infraspinatus tendon is also performed using a shuttle-relay device. Sutures are passed in a horizontal mattress fashion and then visualized and tied down in the subacromial/subdeltoid space, creating the posterior capsulodesis and infraspinatus tenodesis and filling the Hill–Sachs defect. 
Postoperative Management.
The protocol is the same as that for an open capsulolabral repair. 
Pitfalls and Solutions.
These pitfalls are the same as with an open repair, with the notable exceptions below (Table 40-14). 
 
Table 40-14
Arthroscopic Soft Tissue Repair
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Table 40-14
Arthroscopic Soft Tissue Repair
Potential Pitfalls and Solutions
Pitfalls Solutions
Nerve injury Avoid excessive humeral head distraction if using arm traction
Chondrolysis Avoid thermal capsulorrhaphy and intra-articular pain pumps
X
Outcomes
Arthroscopic Anterior Capsulolabral (Bankart) Repairs.
Good-to-excellent results have been reported in the vast majority of patients undergoing arthroscopic Bankart repair, including high-demand patients, such as collegiate and professional overhead athletes.7,38,48,75,173,163,203,265,283,332,342,350,375 At relatively short-term follow-up, rates of recurrent instability have been reported from 0% to 10% in most patients, and 12.5% to 16.5% for high-demand athletes.48,75,173,210,342 At midterm follow-up of 2 to 6 years, recurrent instability rates have been reported as 4% to 7%.171,189,300 Risk factors for recurrent instability following arthroscopic anterior capsulolabral repair include glenoid and/or humeral bone loss, inferior laxity, or MDI instability, use of three or less suture anchors for repair, and the presence of an anterior labroligamentous periosteal sleeve avulsion (ALPSA lesion).35,288 In addition, the instability severity scale (discussed above) was developed by Balg and Boileau14 to help predict patients with higher risks of recurrence after arthroscopic repairs. 
As discussed above, recent data has demonstrated equivalent outcomes between arthroscopic and open capsulolabral (Bankart) repair, including several randomized controlled trials.7,38,75,163,173,203,265,283,332,342,350,375 Petrera et al. performed a meta-analysis to compare the results of open versus arthroscopic Bankart repair for recurrent traumatic anterior instability.265 Only studies directly comparing the two techniques and using suture anchors for repair in both methods were included. Six studies met inclusion criteria (two Level I, four Level III), with 267 patients in the open group (mean follow-up 29.9 months) and 234 in the arthroscopic group (mean follow-up 30.2 months). The rates of recurrent instability (6.7% open vs. 6.0% arthroscopic) and reoperation (6.6% open vs. 4.7% arthroscopic) were not significantly different. Interestingly, recurrent instability (2.9% vs. 9.2%) and reoperation (2.2% vs. 9.2%) were both significantly lower in the arthroscopic group if only studies later than 2002 were included. Functional scores could not be compared because of the different outcome measures used across studies. Importantly, all six studies had strict inclusion criteria and this data cannot be extrapolated to more high risk patients such as patients with significant humeral bone loss, for example. 
In a long-term follow-up study, Zaffagnini et al. compared the results of open versus arthroscopic Bankart repair at 10 to 17 years.375 No significant differences were seen in outcomes in 33 patients undergoing open repair (mean follow-up 15.7 years) and 49 patients undergoing arthroscopic repair (mean follow-up 13.7 years), including recurrent instability (9% open vs. 12.5% arthroscopic). Radiographic findings of glenohumeral arthritis were also not significantly different between groups (18.2% moderate to severe changes in open group vs. 12.2% in arthroscopic group). 
With increasing technology and expertise in arthroscopy, a number of studies have recently reported on the use of arthroscopic surgery in shoulders that were traditionally addressed with open techniques. Patients who have previously failed an instability procedure have undergone arthroscopic revision Bankart repair with reasonable outcomes.38,234 Arthroscopic Bankart repair has also been shown to produce successful results in the setting of smaller amounts of glenoid bone loss, with incorporation of a glenoid rim fragment into the repair, if present.228,271,337,338 
Arthroscopic Repair of HAGL Lesions.
As with open repair, data on arthroscopic repair of HAGL lesions has been limited to small studies or case reports.78,93,180,367 Kon et al. and Field et al. both reported no cases of recurrent instability in small patient series at short-term follow-up.78,180 
Remplissage.
Small series on arthroscopic remplissage, typically performed in combination with arthroscopic Bankart repair, have reported good outcomes with a low rate of recurrent instability.34,242,260,284,376 There have been some reports of loss of shoulder external rotation with the procedure because of the capsulodesis and tenodesis effect.65,121 Boileau et al.34 reported on a series of 47 patients with recurrent instability that underwent arthroscopic Bankart repair and remplissage for a large, engaging Hill–Sachs lesion without substantial glenoid bone loss. At mean 2-year follow-up, 87% good-to-excellent results were reported, with only one case of recurrent instability and 90% of patients returning to sports, including 68% at the same level. In comparison with the contralateral shoulder, mean loss of external rotation was 8 degrees with the arm at the side, and 9 degrees in abduction, with no patient expressing dissatisfaction with this loss of motion. 
Bony Procedures for Recurrent Anterior Instability.
Significant bone loss along the anterior glenoid or from a large Hill–Sachs defect, either in the primary or revision setting, is an indication for a bony procedure for surgical treatment of recurrent anterior instability, as a soft tissue only repair in this setting is associated with a high rate of failure.44,200,228,267 Studies have attempted to determine this critical level of bone loss and although different measurement techniques have been utilized, reported defects of greater than 21% to 30% of the surface area of the glenoid, and a Hill–Sachs defect involving 25% or more of the humeral head or one that engages the anterior glenoid rim with abduction and external rotation, have been identified as indications for bony reconstruction of the glenoid and/or humeral head.9,44,107,149,224,230,267,276,279 Although substantial bone loss is more commonly seen along the glenoid than the humeral head, the combined bone loss on both sides of the joint should be taken into consideration in surgical decision-making.267,341,370 
Typically, glenoid bone loss of 25% of the surface area of the glenoid is an indication for bony reconstruction of this defect, which is most commonly anteroinferior.267,279 Several different bone augmentation techniques have been described; including the Latarjet procedure, use of iliac crest autograft, or use of structural allograft. All function to fill the glenoid defect with a structural bone graft taken from another site. Theoretically, any of these procedures can work if the bone and soft tissue deficiency is adequately addressed. However, the Latarjet procedure, involving transfer of the coracoid process to the anteroinferior glenoid, has been the most well studied and popular of these techniques.134136 Use of iliac crest or allograft may be necessary if bone loss exceeds what can be reconstructed with a coracoid transfer. Reconstruction of a large Hill–Sachs defect can be performed with allograft bone or a partial resurfacing implant.9,224,276,279 
Preoperative Planning (Table 40-15)
 
Table 40-15
Open Bony Procedures for Recurrent Anterior Instability
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Table 40-15
Open Bony Procedures for Recurrent Anterior Instability
Preoperative Planning
  •  
    Beach-chair table with pneumatic arm holder
  •  
    Fluoroscopy may be needed to check bone graft placement, or direction and length of screws
  •  
    Standard open shoulder instruments
  •  
    Additional equipment, as needed, for potential bony or soft tissue procedures (suture anchors, small fragment set, etc.)
    •  
      Fresh frozen allograft for glenoid defect
    •  
      Size-matched fresh frozen allograft for humeral head defect
    •  
      Screws for fixation of glenoid and/or humeral head graft
  •  
    Suture anchors for labral repair
  •  
    Orthosis for arm immobilization should be placed after surgery
X
Positioning.
The beach-chair position is used as described above. 
Surgical Approach.
Although cases necessitating bony reconstruction require an open deltopectoral approach, an initial arthroscopic evaluation of the glenohumeral joint may still be necessary to confirm or determine that bony reconstruction of a glenoid and/or Hill–Sachs defect is required. 
Technique
Latarjet Procedure.
Before entering the glenohumeral joint, the coracoid is exposed for osteotomy. The pectoralis minor tendon is released from the medial aspect of the coracoid, and the bone is exposed proximally to its base. Coracoid osteotomy can be performed with an osteotome or angled, oscillating saw with the cut made starting along the superior surface of the bone, just anterior to the coracoclavicular ligaments near the coracoid base, in a medial-to-lateral direction (Fig. 40-46). The coracoacromial ligament is then released, leaving a 1-cm stump of the ligament attached to the coracoid process laterally. The conjoined tendon (coracobrachialis and short head of the biceps) remains attached to the osteotomized coracoid, and it is mobilized to allow for placement along the anteroinferior glenoid. Care should be taken to avoid injury to the musculocutaneous nerve during mobilization. 
Figure 40-46
Coracoid exposure and osteotomy for Latarjet procedure.
 
Coracoid osteotomy can be performed with an osteotome or angled, oscillating saw, with the cut made starting along the superior surface of the bone, just anterior to the coracoclavicular ligaments near the coracoid base, in a medial-to-lateral direction. A 1-cm stump of the coracoacromial ligament is left attached to the coracoid.
Coracoid osteotomy can be performed with an osteotome or angled, oscillating saw, with the cut made starting along the superior surface of the bone, just anterior to the coracoclavicular ligaments near the coracoid base, in a medial-to-lateral direction. A 1-cm stump of the coracoacromial ligament is left attached to the coracoid.
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Figure 40-46
Coracoid exposure and osteotomy for Latarjet procedure.
Coracoid osteotomy can be performed with an osteotome or angled, oscillating saw, with the cut made starting along the superior surface of the bone, just anterior to the coracoclavicular ligaments near the coracoid base, in a medial-to-lateral direction. A 1-cm stump of the coracoacromial ligament is left attached to the coracoid.
Coracoid osteotomy can be performed with an osteotome or angled, oscillating saw, with the cut made starting along the superior surface of the bone, just anterior to the coracoclavicular ligaments near the coracoid base, in a medial-to-lateral direction. A 1-cm stump of the coracoacromial ligament is left attached to the coracoid.
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X
The glenohumeral joint is next exposed similar to an open Bankart repair. The glenoid rim and neck in the area of the defect are debrided of any soft tissue and lightly decorticated with a high-speed burr to establish a bed of healthy, bleeding bone for osseous union. The same procedure is performed on the coracoid surface that will be placed into the defect site. Superior and inferior drill holes are then made through the coracoid graft for screw fixation. The bone is placed in the glenoid defect (typically below the glenoid equator for an anteroinferior lesion), flush with the glenoid rim. The position can be held with temporary K-wire fixation. The superior hole in the coracoid is then used to drill through the glenoid bicortically, followed by screw placement. The same steps are then repeated to place the inferior screw (Fig. 40-47). Partially threaded, 4.0-mm cancellous or 3.5-mm cortical screws can be used for coracoid fixation in a “lag” fashion, and typically measure 30 to 36 mm in length. 
Figure 40-47
 
Anteroposterior (A) and (B) lateral views following fixation of the coracoid graft to the anterior glenoid. C: The stump of the coracoacromial ligament is repaired to the lateral capsular flap made during capsular incision. Note the sling effect created by placement of the coracoid graft through the split in the subscapularis. The inferior third of the subscapularis is maintained in an inferior position, further stabilizing the glenohumeral joint. From ElAttrache NS, Harner CD. Surgical Techniques in Sports Medicine. Wolters Kluwer Health; 2006.
Anteroposterior (A) and (B) lateral views following fixation of the coracoid graft to the anterior glenoid. C: The stump of the coracoacromial ligament is repaired to the lateral capsular flap made during capsular incision. Note the sling effect created by placement of the coracoid graft through the split in the subscapularis. The inferior third of the subscapularis is maintained in an inferior position, further stabilizing the glenohumeral joint. From ElAttrache NS, Harner CD. Surgical Techniques in Sports Medicine. Wolters Kluwer Health; 2006.
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Figure 40-47
Anteroposterior (A) and (B) lateral views following fixation of the coracoid graft to the anterior glenoid. C: The stump of the coracoacromial ligament is repaired to the lateral capsular flap made during capsular incision. Note the sling effect created by placement of the coracoid graft through the split in the subscapularis. The inferior third of the subscapularis is maintained in an inferior position, further stabilizing the glenohumeral joint. From ElAttrache NS, Harner CD. Surgical Techniques in Sports Medicine. Wolters Kluwer Health; 2006.
Anteroposterior (A) and (B) lateral views following fixation of the coracoid graft to the anterior glenoid. C: The stump of the coracoacromial ligament is repaired to the lateral capsular flap made during capsular incision. Note the sling effect created by placement of the coracoid graft through the split in the subscapularis. The inferior third of the subscapularis is maintained in an inferior position, further stabilizing the glenohumeral joint. From ElAttrache NS, Harner CD. Surgical Techniques in Sports Medicine. Wolters Kluwer Health; 2006.
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X
Differences in placement of the coracoid transfer and subsequent soft tissue repair have been described.276 The inferior surface can be placed against the glenoid defect site, with the stump of the coracoacromial ligament directed laterally. The lateral capsular flap made during capsular incision can then be repaired to the coracoacromial ligament stump, creating an intra-articular graft (Fig. 40-47C). The graft can be made extra-articular by repairing the native capsule to the native glenoid rim using suture anchors or bone tunnels, which must be placed prior to fixation of the coracoid graft. Burkhart et al. described extra-articular graft placement using suture anchors for the capsular repair, and also placed the medial surface of the coracoid graft against the glenoid defect site (Fig. 40-48).45 This technique creates a longer articulating surface in the anterior-to-posterior direction when compared with placing the inferior surface of the coracoid into the defect site. However, the width of bone for screw placement is narrowed and care should be taken to avoid fracture of the graft. 
Figure 40-48
 
A, B: Placement of the medial surface of the coracoid graft against the glenoid defect site. Extra-articular graft placement has been described with this technique, with suture anchors placed along the native glenoid rim (A). C: Repair of the native capsule to the native glenoid rim using the suture anchors puts the coracoid graft in an extra-articular position. (From Burkhart SS, De Beer JF, Barth JR, Cresswell T, Roberts C, Richards DP. Results of modified Latarjet reconstruction in patients with anteroinferior instability and significant bone loss. Arthroscopy. 2007;23(10):1033–1041, with permission)
A, B: Placement of the medial surface of the coracoid graft against the glenoid defect site. Extra-articular graft placement has been described with this technique, with suture anchors placed along the native glenoid rim (A). C: Repair of the native capsule to the native glenoid rim using the suture anchors puts the coracoid graft in an extra-articular position. (From Burkhart SS, De Beer JF, Barth JR, Cresswell T, Roberts C, Richards DP. Results of modified Latarjet reconstruction in patients with anteroinferior instability and significant bone loss. Arthroscopy. 2007;23(10):1033–1041, with permission)
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Figure 40-48
A, B: Placement of the medial surface of the coracoid graft against the glenoid defect site. Extra-articular graft placement has been described with this technique, with suture anchors placed along the native glenoid rim (A). C: Repair of the native capsule to the native glenoid rim using the suture anchors puts the coracoid graft in an extra-articular position. (From Burkhart SS, De Beer JF, Barth JR, Cresswell T, Roberts C, Richards DP. Results of modified Latarjet reconstruction in patients with anteroinferior instability and significant bone loss. Arthroscopy. 2007;23(10):1033–1041, with permission)
A, B: Placement of the medial surface of the coracoid graft against the glenoid defect site. Extra-articular graft placement has been described with this technique, with suture anchors placed along the native glenoid rim (A). C: Repair of the native capsule to the native glenoid rim using the suture anchors puts the coracoid graft in an extra-articular position. (From Burkhart SS, De Beer JF, Barth JR, Cresswell T, Roberts C, Richards DP. Results of modified Latarjet reconstruction in patients with anteroinferior instability and significant bone loss. Arthroscopy. 2007;23(10):1033–1041, with permission)
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X
In theory, stabilization of the glenohumeral joint occurs by three mechanisms with the Latarjet procedure: (1) A bony effect by correcting the anterior glenoid deficiency; (2) a muscular (“sling”) effect created by maintaining the inferior third of the subscapularis in an inferior position by the conjoined tendon (Fig. 40-47C); and (3) a capsular effect by the capsular repair or repair of the coracoacromial ligament to the capsule at the end of the procedure. 
Iliac Crest Autograft or Allograft Glenoid Reconstruction.
The anterior glenoid bone defect is exposed and prepared similarly to the Latarjet procedure. A tricortical iliac crest autograft is obtained and sized to fit the bone defect. A graft that is 3 cm long and 2 cm deep is usually of adequate size. The inner table of the iliac crest has a similar contour to the glenoid surface and is, therefore, faced laterally when secured to the native glenoid. Graft position and fixation is performed similar to the Latarjet procedure, with partially threaded, 4.0-mm cancellous or 3.5-mm cortical screws utilized. The graft can be made intra-articular or extra-articular based on the capsular repair. Repair of the lateral capsular flap with sutures secured around the screw heads creates an intra-articular graft, whereas repairing the native capsule to the native glenoid rim leaves the graft extra-articular. 
Fresh or fresh-frozen allograft may be used similar to iliac crest autograft, while avoiding the morbidity of graft harvest. Glenoid allograft provides an ideal match to native anatomy, but may be difficult to obtain.280 
Reconstruction of Hill–Sachs Defect.
To access the Hill–Sachs defect through a standard deltopectoral approach, a subscapularis tenotomy is performed, as described above. The humeral head is then dislocated from the glenohumeral joint and the Hill–Sachs defect exposed with simultaneous adduction, extension, and maximal external rotation of the arm. An oscillating saw is used to contour the bone into a wedge-shaped defect to accept an allograft. The length, width, and height of the prepared area are then measured and the allograft bone is cut to the matching size. A fresh or fresh-frozen humeral head or femoral head allograft can be used as a graft source, but care must be taken to obtain a graft that is appropriately sided and sized for the patient. The allograft bone is then fitted into the defect and further contoured as needed to create a smooth articular transition between native and allograft bone. The graft is then fixed to native bone using two, 3.0 or 3.5-mm cannulated screws with countersunk heads (Fig. 40-49). Anterior capsulolabral repair or glenoid bone grafting is performed after reconstruction of the Hill–Sachs lesion if both procedures are necessary. 
Cannulated screws can be placed over the guidewires for definitive graft fixation.
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Figure 40-49
After appropriate contouring of the defect and graft, the allograft bone is fitted into the Hill–Sachs defect and provisionally held in place with guidewires.
Cannulated screws can be placed over the guidewires for definitive graft fixation.
Cannulated screws can be placed over the guidewires for definitive graft fixation.
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Postoperative Management.
The protocol is the same as that for an open capsulolabral repair. 
Pitfalls and Solutions (Table 40-16)
 
Table 40-16
Open Bony Procedures for Recurrent Anterior Instability
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Table 40-16
Open Bony Procedures for Recurrent Anterior Instability
Potential Pitfalls and Solutions
Pitfalls Solutions
Axillary nerve injury Avoid being too inferior in the surgical approach
Avoid excessive humeral head distraction
Musculocutaneous nerve injury Adequate mobilization of conjoint tendon during coracoid transfer
Avoid lateral overhang of glenoid bone graft Use temporary K-wires to judge graft placement
Prominent hardware Screws in glenoid graft placed away from the articular surface
Screws in humeral graft adequately countersunk
Fixation failure Two screws needed for fixation of humeral head or glenoid bone graft
Intraoperative fracture of graft Avoid using too small a graft
Inadequate bony reconstruction Avoid using too small a graft
X
Outcomes
Latarjet Procedure.
Long-term studies of the Latarjet procedure have shown good-to-excellent clinical results in 86% to 97% of the patients, with reported recurrent instability rates of 7% to 13.6%.2,134136,138,139,325 The procedure has been associated with the development of glenohumeral joint arthrosis, with radiographic evidence of arthropathy seen in as many as 71% of the patients, although the majority of the changes are mild.2,134136,138,139,325 Hovelius et al. have extensively reported on the procedure over several long-term studies.134136,138,139 In a prospective study of 118 shoulders followed for a mean of 15.2 years, the authors reported good or excellent results in 86% of patients, with 98% of patients satisfied or very satisfied with the procedure.136 Redislocation occurred in 3.4% of patients, with one patient requiring revision surgery, and recurrent subluxations occurred in 10.2% of patients. Mean loss of external rotation at the side was 10.7 degrees. In a subsequent study, the same patient cohort was evaluated for radiographic development of arthrosis at 15-year follow-up.135 Bony healing of the graft was seen in 85% of patients, with moderate-to-severe arthropathy at the glenohumeral joint in 14% of patients, and mild arthropathy in 35%. A lower percentage of moderate-to-severe arthropathy was seen when the graft was placed medial to the glenoid rim, and when the screw and graft were parallel to the joint line, but this difference was not significant. 
Recently a large analysis noted better outcomes in Latarjet patients compared to Bankart patients at mean 17-year follow-up.138 This included revision surgery because of recurrent instability (1% vs. 5.6%, p = 0.08), rate of recurrent instability (13.4% vs. 28.7%, p = 0.017), patient satisfaction (97% vs. 90%, p = 0.0.01), mean WOSI score (88 vs. 79, p = 0.002), and mean loss of external rotation with the arm at the side (11 degrees vs. 19 degrees, p = 0.012). 
Finally, a recent systematic review examined complication and reoperation rates following original or the modified version of the Bristow or Latarjet procedure.108 A total of 1,904 cases across 45 studies (all Level IV) were reviewed, and recurrent dislocation and subluxation rates were 2.9% and 5.8%, respectively. Most dislocations occurred in the first year postoperatively, but only 7% of patients required reoperation. 
Iliac Crest Bone Graft.
Long-term studies of the use of iliac crest bone graft with older techniques have shown good-to-excellent results in 75% to 85% of the patients.41,285,287 Reported rates of recurrent instability have ranged from 4% to 33%.41,181,285,287 Radiographic evidence of joint arthrosis has also been reported in 33% to 89% of patients at long-term follow-up.181,285,287 Studies utilizing more modern methods of graft fixation and contouring to the native articular surface have shown good results and a low rate of recurrent instability.19,113,168,319,355 Warner et al. reported on the use of tricortical iliac crest autograft for significant anterior glenoid bone defects in a series of 11 patients with recurrent instability.355 At mean 33-month follow-up, all grafts had incorporated and there were no cases of recurrent instability. 
The use of allograft for anterior glenoid reconstruction has only been reported in small series.168,280,360 Weng et al. reported on the use of femoral head allograft in nine patients with recurrent instability and large anterior glenoid bone defects.360 Minimum follow-up was 4.5 years, with all grafts incorporating and a mean Rowe score of 84. One redislocation occurred in one patient, and one subluxation occurred in another, both following grand mal seizures, with no further instability developing. 
Reconstruction of Hill–Sachs Defect.
Clinical outcomes on reconstruction of large Hill–Sachs defects have been limited to small studies or case reports.110,224,231,343,369 Miniaci and Gish reported on the use of a humeral head allograft in 18 patients with prior failed instability surgery and a Hill–Sachs lesion involving more than 25% of the humeral head.224 At minimum 2-year follow-up, there were no cases of recurrent instability, with a mean Constant score of 78.5, and 89% of patients had return to work. Interestingly, in our limited experience, many of the patients requiring reconstruction have uncontrolled seizure disorders leading to recurrent instability and humeral head bone loss. 

Posterior Instability

As discussed above, posterior instability is relatively uncommon accounting for less than 2% to 12% of overall instability.37 Seizures, motor vehicle accidents, substance abuse, systemic disease (e.g., Ehlers–Danlos), and psychiatric illness all have been associated with posterior instability.298 Management should be discussed by the type of instability: Acute dislocation (<3 weeks) which is rare, chronic dislocation which is even more uncommon, and recurrent instability which is the most common form. The use of 3 weeks is arbitrary, but as discussed below, attempted closed reduction becomes less successful around this time. 
The pathogenesis of recurrent instability may start with an acute dislocation; however, it typically starts with subluxation and an atraumatic or microtraumatic etiology as discussed above. Last, it should be noted that because recurrent posterior instability is relatively uncommon, few surgeons encounter it often though it is now being recognized with increasing frequency. Errors in diagnosis and management are common and evidence-based management is lacking. Almost all the reported literature are case series and the definitions of posterior instability are unclear. 

Nonoperative and Closed Treatment

Indications/Contraindications
Acute Posterior Dislocations.
Unless a patient is severely infirm and unable to tolerate an attempt at closed reduction, intervention (closed or open) should always be considered. There are few other indications to leave an acute dislocation unreduced and treated nonoperatively. Similarly, a reduced dislocation that has persistent subluxation or instability because of a large glenoid fracture should always be considered for surgical intervention. This is discussed in more detail in the scapular fracture chapter. 
Chronic Posterior Dislocations.
If a patient has a chronic dislocation (>3 to 6 weeks), attempt at closed reduction without full muscle relaxation should not be attempted because of the risk of fracture and neurovascular injury (Fig. 40-1). The typical history is a violent dislocation during a motor vehicle accident or a seizure. The patient may be unaware of the injury or intubated and sedated, and the injury can go unrecognized for a long period of time. Though surgical management is standard for patients who are infirm or have reasonably good function and minimal pain, nonoperative treatment may be the appropriate choice. All patients with a posterior dislocation will have limited motion—specifically anterior elevation and external rotation, but sometimes it can be as high as 60% to 85% of normal.357 In agreement with others, we have observed some patients to have minimal pain. Therefore with a functional contralateral arm and limited demand, nonoperative treatment may be the best treatment. For patients with epilepsy, the seizures need to be controlled before any surgery is considered. If the seizures are frequent and uncontrollable, consideration should also be given to nonoperative treatment. 
Recurrent Posterior Instability.
For recurrent posterior instability, vigorous nonoperative management is the mainstay as the pathogenesis is incompletely understood and the results of posterior repair are unpredictable. Many shoulders are managed with strengthening, education, neuromuscular rehabilitation, and even psychological counseling for patients with voluntary instability. Strengthening is focused on the dynamic stabilizers, specifically the rotator cuff, posterior deltoid and the periscapular muscles. Surgery is only considered for involuntary recurrent instability after failed nonoperative treatment. Physical therapy, however, is more likely to be successful in the absence of a large reverse labral lesion or bony defect. The success rate of an exercise program in patients with disabling symptoms was as high as 68% in one study.82 Many of these patients were improved, but still had some recurrences of instability. Conversely, some studies show that patients who fail therapy have a surgical success rate as high as 90% (Table 40-17).82 
 
Table 40-17
Posterior Instability
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Table 40-17
Posterior Instability
Nonoperative Treatment
Indications Contraindications
Recurrent atruamatic instability Acute dislocation
Infirm patient Acute destabilizing glenoid fracture
Chronic dislocation with good function
Unstable epilepsy
Open injuries
X
Closed Reduction.
Many posterior dislocations are locked and initially missed with the exact timing of the injury sometimes unclear. In addition, 30% to 40% of dislocations have an associated fracture301 and for these reasons, closed reduction requires complete muscle relaxation and fluoroscopy. In our institution, all of these dislocations are taken to the operating room for closed reduction and are not reduced in the emergency room. In the OR, postreduction stability can be assessed, real-time fluoroscopy can be used to help guide the reduction and prevent the catastrophic creation of a humeral neck or head fracture. If after a first careful attempt at reduction is unsuccessful, consideration for open or arthroscopic reduction and stabilization is suggested and easily performed in the OR. 
With a moderately sized humeral head defect (>20% to 25%) an attempt at closed reduction has a higher risk of recurrent instability. Some authors use this as a relative indication for open management,263 whereas others, including ourselves, have had success with closed treatment. Close attention to detail and gentle maneuvers are required along with assessment of postreduction stability. Recurrent instability beyond neutral arm rotation should be considered an indication for an operative stabilizing procedure, as discussed below. 
Importantly, there is no clear timeframe to define an “acute” versus “chronic” dislocation; however, reduction appears to be more difficult after 3 weeks and it is often cited as the division between the two.126 Known nondisplaced fractures, in our opinion, should be treated open to decrease the risk of displacement. 
Preoperative Planning.
We always prepare for an open procedure in case a closed reduction is not successful. Some authors have discussed using arthroscopy-assisted reduction using standard portals: we have no experience with this (Table 40-18). 
 
Table 40-18
Closed Reduction of a Posterior Dislocation
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Table 40-18
Closed Reduction of a Posterior Dislocation
Preoperative Planning
  •  
    Radiolucent or beach-chair table
  •  
    Supine or beach-chair angled in the room to allow for fluoroscopy
  •  
    Lateral position with bean-bag if arthroscopy is considered
  •  
    Fluoroscopy coming in from the head parallel to the table for supine and beach-chair positioning.
  •  
    Fluoroscopy coming in from the foot for lateral positioning.
  •  
    Preparation for open or arthroscopic procedure (see below)
  •  
    Orthosis in neutral arm rotation should be available postoperatively
X
Positioning.
In the OR, the patient can be placed in a beach-chair position or supine on a radiolucent table. If consideration is given to arthroscopy and the preferred position for this technique is lateral (as opposed to beach-chair), lateral position with a bean bag should be used. 
Fluoroscopy should be used to get orthogonal views. This is most easily done with the machine coming cephalad on the side of dislocated shoulder with the C rotating to get an axillary and AP or Grashey view (Fig. 40-50). This C-arm positioning works for supine and beach-chair, but works best from the foot for lateral positioning. Positions must include potential access to anterior and posterior shoulder. 
Figure 40-50
Intraoperative positioning in the beach-chair position with the C-arm coming over the top for both a (A) true AP and (B) axillary view.
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Technique.
The reduction maneuver is forward flexion with the arm in adduction and internal rotation. As an assistant places gentle cross-body traction, gentle digital pressure is placed on the posterior humeral head. In addition, gentle internal and external rotation can be used to disimpact the reverse Hill–Sachs lesion. Once the head is disimpacted, the head should be brought anteriorly and externally rotated. Aggressive external rotation against resistance can lead to a shearing fracture of the humeral head or neck. Stability of the joint should be tested in adduction with gentle range of motion under fluoroscopy. Specifically, stability in internal rotation should be checked. Postreduction, the arm should be placed in neutral rotation with a bump under the sling or a “gun-slinger orthosis” splint. Consideration should be given to further open procedures if instability is encountered at a neutral arm position or beyond. 
Postoperative Management.
The patient is kept 3 to 6 weeks in a sling in a neutral position. We prefer a longer timeframe to allow the posterior capsule to heal. Elbow, wrist, and hand motions are encouraged during this time. A strengthening program is started once the splint or orthosis is discontinued. Persistent instability after nonoperative management will require operative intervention as discussed below. 
Pitfalls and Solutions (Table 40-19)
 
Table 40-19
Closed Reduction of a Posterior Dislocation
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Table 40-19
Closed Reduction of a Posterior Dislocation
Potential Pitfalls and Solutions
Pitfalls Solutions
Displacement of fracture ORIF
Hemiarthroplasty
Acute instability External rotation orthosis
Open anterior procedure (below)
Arthroscopic capsulorrhaphy
Recurrent instability Open or arthroscopic procedure discussed below
X
Outcomes.
Patients with a successful closed reduction, even with initial instability in internal rotation, have been reported to have excellent outcomes with near full motion and limited pain in both the short and long terms. The most common complication after this injury is recurrent instability, occurring in approximately 15% to 20% of patients and typically within the first year.301 Predisposing factors for recurrent instability are size of the humeral defect, dislocation because of seizure, and age less than 40. The risk is lower in patients following a MVA or with a traumatic incident—specifically if the patient is older and has a small anterior humeral head defect. There are small but persistent deficits of shoulder function by outcomes scores, though most series report generally good function.263,297,301 

Operative Treatment of Posterior Instability

Indications/Contraindications
Acute Posterior Dislocations.
In the acute setting, the indications for surgery are irreducible or unstable dislocations, dislocation-associated fracture of the proximal humerus, open injuries, a significant glenoid fracture contributing to instability, or a reverse Hill–Sachs >20% to 25%. Most, if not all proximal humerus fractures identified preoperatively should be treated with open reduction with or without fixation because of the high risk of displacement and catastrophic consequences if a forceful closed reduction is performed (Fig. 40-51). 
Figure 40-51
Acute posterior dislocation.
 
Note the fracture (arrow) that could further displace with attempted closed reduction.
Note the fracture (arrow) that could further displace with attempted closed reduction.
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Figure 40-51
Acute posterior dislocation.
Note the fracture (arrow) that could further displace with attempted closed reduction.
Note the fracture (arrow) that could further displace with attempted closed reduction.
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Chronic Posterior Dislocations.
The indications for nonoperative treatment or “skillful neglect” were discussed above. However, for all other patients, the results of operative intervention are generally superior to nonoperative care. The choice of procedure, as discussed below, depends on the size of the humeral head defect and patient factors. 
Recurrent Posterior Instability.
For recurrent instability, surgical stabilization is indicated if nonoperative treatment has failed. These procedures may be performed arthroscopically, or through an open posterior approach with or without a bony procedure (glenoid osteotomy or posterior bone block procedure). Arthroscopic procedures have the benefit of evaluating the entire joint before treatment and limiting patient morbidity, but these procedures are technically challenging. Arthroscopic repairs are contraindicated in the setting of glenoid abnormalities (e.g., glenoid retroversion) that need to be addressed. In addition, many patients with posterior instability have inferior or bidirectional instability which also needs to be addressed (Table 40-20). 
 
Table 40-20
Posterior Instability
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Table 40-20
Posterior Instability
Operative Treatment
Indications Contraindications
Failed nonoperative treatment for recurrent instability Unstable epilepsy
Failed closed reduction Infirm patient
Dislocation >3–6 wks
Reverse Hill–Sachs >20–25%
Significant glenoid defect
Proximal humerus fracture
X
Open Anterior Reduction of a Posterior Dislocation51.
If a stable closed reduction is unsuccessful, the patient has a defect >20% to 25% of the humeral head, or the patient has had a dislocation for >3 weeks, an open reduction with or without additional procedures such as disimpaction of the reverse Hill–Sachs defect is indicated. If, however, the humeral head defect is greater than 40%, other anterior techniques that address the lesion are indicated because of the extremely high risk of recurrent dislocation. These techniques, including subscapularis transfer, lesser tuberosity transfer, or hemiarthroplasty, are discussed later in the setting of chronic posterior dislocations. 
Preoperative Planning.
Despite the chronicity of a dislocation, an anterior approach is the work-horse for open reduction because it is a safe and standard approach. A surgeon should also be prepared for a posterior approach if the anterior approach is unsuccessful, but this is uncommon. In addition, the surgeon should be prepared for a disimpaction of a small reverse Hill–Sachs defect if necessary. Fluoroscopy or intraoperative radiographs should be considered to confirm reduction and to evaluate fracture displacement. The setup is similar to the closed reduction setup of posterior dislocations (Table 40-21). 
 
Table 40-21
Open Anterior Reduction of a Posterior Dislocation
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Table 40-21
Open Anterior Reduction of a Posterior Dislocation
Preoperative Planning
  •  
    Refer to setup for closed reduction of a posterior dislocation
  •  
    Standard open shoulder instruments
  •  
    Narrow, long tamps and cancellous allograft are needed for the disimpaction procedure (if considered)
  •  
    An oscillating saw and curved ostetomes are needed for the lesser tuberosity osteotomy
  •  
    A small fragment set and power should be available
X
Positioning.
Our standard setup is in beach-chair position with an articulated arm holder as in all our open anterior procedures. As with closed reductions, both a lateral and supine position can be used. The lateral position also allows for arthroscopy (if preferred laterally) and for a posterior approach. A supine position is the simplest, but does not allow for a posterior approach if required. In addition, the lateral or supine positions are poor for an arthroplasty procedure, if required. 
Surgical Approach and Technique.
A standard deltopectoral approach is used with the biceps tendon as a guide to find the lesser tuberosity. The tendon is best found distally, medial to the pectoralis major insertion. In the setting of a posterior dislocation, the axillary nerve is precariously close medially and is very taut. The nerve should be palpated or seen before any surgical releases are attempted. In simple situations, the biceps tendon can be followed and the rotator interval released to gain access to the joint. A finger can be placed through the interval and into the joint to manually pull the humeral head laterally to disimpact the head with the arm in an adducted and slightly flexed position. Once the humeral head is disimpacted, it can be brought anteriorly with digital pressure and the arm can be externally rotated, aiding in reduction. Stability of the reduction should be tested in adduction, as with bringing the arm into internal rotation. Positioning of the arm postoperatively, is determined by this intraoperative stability. 
If a reduction cannot be performed through the interval, then the subscapularis can be released (and subsequently repaired) in the standard techniques described above for anterior instability. The humeral head can be reduced manually or by lateral traction with a bone hook. Care should be taken to not damage the cartilage. 
Last, if the humeral head defect is large, humeral head disimpaction or subscapularis transfer should be considered (discussed below). A disimpaction procedure should only be considered if the humeral head bone stock is good, the impacted cartilage can be salvaged, the defect is <40%, and the dislocation is less the 3 weeks. Chronic dislocations suffer from disuse osteopenia. 
A cortical window is created with internal rotation of the humeral head in the greater tuberosity, though in reality it is difficult to preserve the cortical bone. A large tamp is introduced to disimpact the fracture. The head needs to be externally rotated to check elevation progress. The humeral head void is filled with cancellous allograft (our preferred choice), iliac crest, or another bone substitute product (Fig. 40-52). 
Figure 40-52
Disimpaction of an acute reverse Hill Sachs defect using a cortical window opposite to the lesion (A), to pack cancellous bone graft into the defect (B).
Sometimes the disimpaction is supported by screws (C).
Sometimes the disimpaction is supported by screws (C).
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Postoperative Management.
Postoperative treatment is similar to that in closed management. A brace in neutral position is used for 6 weeks. 
Pearls and Pitfalls (Table 40-22)
 
Table 40-22
Open Anterior Reduction of a Posterior Dislocation
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Table 40-22
Open Anterior Reduction of a Posterior Dislocation
Potential Pitfalls and Solutions
Pitfalls Solutions
Displacement of fracture ORIF
Hemiarthroplasty
Acute instability External rotation orthosis
Subscapularis transfer (below)
Posterior approach and capsular repair
Irreducible dislocation Posterior approach
Axillary nerve injury Direct repair
Observation
X
Outcomes.
There is limited data on the outcomes of simple open reduction. All the literature includes additional subscapularis transfer or capsulorrhaphy. However, in our limited experience, the open and closed reductions have similar and generally excellent outcomes. In addition, subscapularis transfer or capsulorrhaphy is not often required.56 The chance of recurrence is likely similar.70,126 There are only a few series looking at disimpaction in isolation: They reveal that success correlates with good bone stock.167 
Open Anterior Procedures for Chronic Posterior Dislocations.
Following (open reduction or gentle attempt at closed reduction) the humeral head stability is tested with adduction and internal rotation. As the size of the reverse Hill–Sachs increases, so does the degree of instability. With instability in neutral, an adjunctive stabilization procedure should be considered. With defects smaller than 20% of the humeral head, a subscapularis transfer with (modified McLaughlin) or without the lesser tuberosity (McLaughlin) is recommended. For patients with a 20% to 40% defect, an osteoarticular allograft should be considered. In most cases, an arthroplasty is needed for defects larger than 40%. In addition, as the time from injury increases, so does the disuse osteopenia and the need for an arthroplasty. Preparation for an arthoplasty should therefore, always be considered. The guidelines are based mainly on expert observation with no evidence-based studies available. 
Preoperative Planning (Table 40-23)
 
Table 40-23
Open Anterior Procedures for Chronic Posterior Dislocations
Preoperative Planning
  •  
    Beach-chair table with pneumatic arm holder
  •  
    Fluoroscopy may be needed to check direction and length of screws
  •  
    Equipment is the same as an open anterior stabilization
    •  
      Small oscilllating saw needed for lesser tuberosity transfer
    •  
      Size-matched fresh frozen allograft of the humeral head
    •  
      Headless screws needed for fixation of allograft
    •  
      Arthroplasty equipment should always be available
  •  
    External rotation orthosis should be available
X
Positioning.
The beach-chair position is used as described above. 
Surgical Approach.
A standard deltopectoral approach is used for all these stabilizations. 
Technique
Subscapularis Transfer.
The approach is the same as described above for open reduction. The biceps is identified at the lateralmost aspect of the subscapularis insertion on the lesser tuberosity. From here, the subscapularis tendon, along with the underlying capsule are reflected from the tuberosity as a sleeve and tagged. The joint is exposed and the head reduced as described above. Careful attention should be paid to the axillary nerve which is very taut in posterior dislocations. The scar tissue is debrided and the joint inspected. If the bony defect is less than 20% of the humeral head surface and the remaining cartilage is in good condition, the tendon can be transferred into the defect. The subscapularis tendon and capsule are transferred into the defect and held in position with #2 nonabsorbable transosseous sutures. We prefer to release the biceps from the supraglenoid tubercle and tenodese it to the superior aspect of the pectoralis major tendon. This allows us to pass the drill holes through the bicipital groove which generally has excellent bone quality. Anchors can also be used to secure the tendon, but this is not our preference as bone tunnels are cheaper and generally stronger (Fig. 40-53A). The humeral head should be tested for stability. If instability still exists, or the remaining cartilage in poor condition, consideration should be given to the other procedures. 
Figure 40-53
 
A: The McLaughlin operation. In the presence of a large anterior humeral head lesion, the subscapularis tendon can be transferred into the defect. B: A subsequent modification by Neer transfers the lesser tuberosity with the attached subscapularis tendon.
A: The McLaughlin operation. In the presence of a large anterior humeral head lesion, the subscapularis tendon can be transferred into the defect. B: A subsequent modification by Neer transfers the lesser tuberosity with the attached subscapularis tendon.
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Figure 40-53
A: The McLaughlin operation. In the presence of a large anterior humeral head lesion, the subscapularis tendon can be transferred into the defect. B: A subsequent modification by Neer transfers the lesser tuberosity with the attached subscapularis tendon.
A: The McLaughlin operation. In the presence of a large anterior humeral head lesion, the subscapularis tendon can be transferred into the defect. B: A subsequent modification by Neer transfers the lesser tuberosity with the attached subscapularis tendon.
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Lesser Tuberosity Transfer.
A modification of this procedure was described by Hawkins and Neer (Fig. 40-53B) in which the lesser tuberosity is osteotomized with the attached tendon and transferred into the bony defect.126,215 In this technique, we always release the biceps tendon from the supraglenoid tubercle by opening the rotator interval. We tenodese the tendon to the superior pectoralis major tendon and then perform the osteotomy with a 10-mm oscillating saw followed by a curved osteotome. It is critical to keep the bony piece thick to hold screws and to fill the defect. After the joint is reduced and evaluated, and the defect debrided to bleeding cancellous bone, the osteotomy can be secured to the defect with two cancellous screws as originally described. Transosseous sutures can augment fixation (Fig. 40-54). 
Figure 40-54
A: Chronic posterior dislocation with <20% defect treated with (B) a lesser tuberosity transfer using suture and bone tunnels.
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Allograft Reconstruction.
The approach is similar to described above.96 We prefer a lesser tuberosity osteotomy for exposure as well as a backup procedure if we have difficulty with the allograft. The edges of the defect are sharply cut with an oscillating saw or osteotome. The defect is measured and the humeral head allograft is cut 2 mm larger to allow for a press fit then contoured as needed. Once the head is well seated, headless screws (or countersunk headed screws) are used for fixation. The shoulder is taken through a range of motion to check stability. The subscapularis or lesser tuberosity osteotomy is repaired with five large nonabsorbable transosseous sutures through the bicipital groove (Fig. 40-55). 
Figure 40-55
 
A: Chronic posterior dislocation. Note large reverse Hill–Sachs defect (40% of head) and heterotopic bone from chronic displacement. B: Treated with humeral head allograft and headless screws.
A: Chronic posterior dislocation. Note large reverse Hill–Sachs defect (40% of head) and heterotopic bone from chronic displacement. B: Treated with humeral head allograft and headless screws.
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Figure 40-55
A: Chronic posterior dislocation. Note large reverse Hill–Sachs defect (40% of head) and heterotopic bone from chronic displacement. B: Treated with humeral head allograft and headless screws.
A: Chronic posterior dislocation. Note large reverse Hill–Sachs defect (40% of head) and heterotopic bone from chronic displacement. B: Treated with humeral head allograft and headless screws.
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Arthroplasty.
If the articular cartilage is in poor condition or the humeral head defect is greater than 40%, a hemiarthroplasty or total shoulder arthroplasty should be used.92,297 Hemiarthroplasty can be used in younger patients below the age of 50 and patients with good glenoid cartilage. Total shoulder replacements should be considered for the others. We perform a lesser tuberosity osteotomy. The head is externally rotated and brought out of the wound where a humeral head cut is made in the anatomic version. Some have discussed anteroverting the humeral head in cases of a locked dislocation to prevent further instability. We prefer not to distort the bony anatomy, which may have implications for long term glenoid wear (bony or prosthetic) or glenoid component loosening. Instead we balance the soft tissue by plicating any lax posterior capsule with figure-of-eight nonabsorable #2 stitches. A glenoid component is placed if the cartilage is poor or the patient is older. The lesser tuberosity is repaired with transosseous sutures through the bicipital groove. 
Postoperative Management.
For all of the above procedures, including arthroplasty, the patient is kept in an orthosis keeping the arm in neutral for 6 weeks to allow the posterior capsule and the subscapularis to heal. We do not allow external rotation beyond neutral as some advocate for fear of disrupting the subscapularis repair. At 6 weeks, full gentle range of motion is allowed with strengthening at 3 months. 
Pitfalls and Solutions (Table 40-24)
 
Table 40-24
Open Anterior Procedures for Chronic Posterior Dislocations
Potential Pitfalls and Solutions
Pitfalls Solutions
Axillary nerve injury Note displacement of nerve on initial approach
Osteopenic head Consider arthroplasty
Pull-out of transosseous sutures Drill through the bicipital groove
Fracture of lesser tuberosity bone Use small screw (2.0 or 2.7 mm)
Consider anchors or transosseous suture
X
Outcomes
Subscapularis and Lesser Tuberosity Transfer.
Only a few studies have been published for subscapularis transfer procedures, but most have reported stable shoulders with congruent motion in the majority of patients who were treated with this operation.51,79,215 Typically forward flexion remains full, although external rotation does have some limitation to approximately 45 degrees as described in a number of reports. 
Allograft Reconstruction.
Allograft reconstruction is safe with satisfactory results.51,68 Gerber first described his results with four patients at 5 years.96 Three patients had excellent results whereas one suffered AVN considered to be related to the patient’s alcohol intake. He advocated this procedure in young patients to restore normal anatomy and shoulder biomechanics. Further, if an arthroplasty is needed subsequently, it is easier to perform after allograft reconstruction than after subscapularis transfer. 
Arthroplasty.
There are limited reports on the use of arthroplasty for chronic posterior dislocations, but the results are mixed. Cheng reported satisfactory results in seven patients with no failures.52 Checcia, however, reported three failures of hemiarthroplasty in eight patients and four failures of five total shoulders. The cause of the failures vary including anterior and posterior instability, nerve injury, limited range of motion, and bony glenoid wear.51 
Open Posterior Capsulorrhaphy for Recurrent Instability
Preoperative Planning (Table 40-25)
 
Table 40-25
Open Posterior Capsulorrhaphy or Labral Repair
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Table 40-25
Open Posterior Capsulorrhaphy or Labral Repair
Preoperative Planning
  •  
    Bean bag for lateral position or beach-chair table with arm holder
  •  
    Fluoroscopy is not needed
  •  
    Standard open shoulder instruments
  •  
    Custom external orthosis should be premade and fitted prior to surgery
X
Positioning.
The patient can be placed prone with the shoulder off the operating room table to allow for full scapular and humeral motion. However, lateral decubitus with the patient supported by a full-length bean bag is preferred by many surgeons. We prefer the beach-chair position because it gives us access to both the anterior and posterior aspect of the shoulder if needed. However, patients have to be placed quite vertical and for larger patients, this can be difficult. 
Surgical Approach.
The posterior approach is as detailed above in the surgical approach section. 
Technique.
The capsule is incised transversely at the midpoint from the medial to lateral direction (away from the suprascapular nerve) followed by a vertical incision 5 mm from its humeral insertion (Fig. 40-56A). The incision must be extended inferiorly enough to address any inferior redundancy. Typically the release to the 6 o’clock position is enough, but with a very lax inferior capsule, it needs to be released all the way around the humeral neck to the anterior inferior side. 
The corners are tagged with traction sutures and a humeral head retractor such as a Fukuda is then easily placed into the joint without damage to the cartilage. The posterior labrum is inspected for a lesion. If a lesion is found, the posterior glenoid neck should be decorticated with a rasp or burr and anchors should be placed—typically three or more (Fig. 40-56B). Sutures are passed around the labrum and tied with the knots on the external surface of the capsule/labrum—acting as a buttress. Before tying, the arm is abducted in the plane of the scapula to 20 degrees and neutral rotation. 
Figure 40-56
 
A: Posterior approach to the shoulder with a Fukuda retractor in the joint. The posterior labrum is repaired with three suture anchors after rasping the posterior glenoid. B: Posterior capsulorrhaphy is initiated with a transverse incision followed by a lateral vertical incision. C: The inferior flap is advanced superiorly and laterally and the superior flap is advanced laterally and inferiorly.
A: Posterior approach to the shoulder with a Fukuda retractor in the joint. The posterior labrum is repaired with three suture anchors after rasping the posterior glenoid. B: Posterior capsulorrhaphy is initiated with a transverse incision followed by a lateral vertical incision. C: The inferior flap is advanced superiorly and laterally and the superior flap is advanced laterally and inferiorly.
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Figure 40-56
A: Posterior approach to the shoulder with a Fukuda retractor in the joint. The posterior labrum is repaired with three suture anchors after rasping the posterior glenoid. B: Posterior capsulorrhaphy is initiated with a transverse incision followed by a lateral vertical incision. C: The inferior flap is advanced superiorly and laterally and the superior flap is advanced laterally and inferiorly.
A: Posterior approach to the shoulder with a Fukuda retractor in the joint. The posterior labrum is repaired with three suture anchors after rasping the posterior glenoid. B: Posterior capsulorrhaphy is initiated with a transverse incision followed by a lateral vertical incision. C: The inferior flap is advanced superiorly and laterally and the superior flap is advanced laterally and inferiorly.
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Attention is then turned to the posteroinferior capsular shift. The inferior capsular flap is then shifted laterally and superiorly, reducing any inferior redundancy, with no. 2 nonabsorable sutures passed and tied laterally. The superior flap is then shifted inferiorly to a point of tension. The interval between the flaps is reinforced with nonabsorbable sutures. At this point, if the infraspinatus tendon is felt to be excessively loose, it can also be slightly shortened by imbricating upon itself (Fig. 40-56C). 
Postoperative Management.
The patient is put into an orthosis in 20 degrees of abduction and 10 degrees of external rotation for 6 weeks. This orthosis generally needs to be made and fitted ahead of surgery. Inferior traction should be avoided along with internal rotation especially during bathing. A gentle range-of-motion program is started. Forward flexion is initially started with the patient supine along with gentle internal rotation. Strengthening is started at 3 months and return to contact sports at 6 months. 
Pitfalls and Solutions (Table 40-26)
 
Table 40-26
Open Posterior Cappsulorraphy and Labral Repair
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Table 40-26
Open Posterior Cappsulorraphy and Labral Repair
Potential Pitfalls and Solutions
Pitfalls Solutions
Axillary nerve injury Avoid being too inferior in the surgical approach
Missed labral tear Inspection of the joint
Inadequate shift of associated inferior redundancy Adequate inferior capsular releases around the humeral neck
Suprascapular nerve injury Minimize medial retraction
Adequate shift Abduction and external rotation of the arm prior to capsular shift
Overtightening Avoid excessive external rotation prior to tying the suture
X
Outcomes.
The results of posterior capsulorrhaphy are generally good according to a small group of recent retrospective case series. These studies have reported good-to-excellent results in 90% to 100% of the patients treated with a primary posterior inferior shift for recurrent posterior instability. The rate drops to 80% when revision cases were included. The recurrence rate of instability has been reported to be between 0% and 23%.27,83,125,225,292,366 Age older than 37 and chondral injury discovered at the time of the procedure have been associated with worse long-term outcomes. 
In a 2005 study by Bottoni et al., looking strictly at patients with the less common traumatic (vs. atraumatic) cause for instability, both open and arthroscopic procedures led to excellent outcomes, but the results favored the arthroscopic procedure in terms of functional scores.37 
Arthroscopic Posterior Capsulorrhaphy for Recurrent Instability
Preoperative Planning (Table 40-27)
 
Table 40-27
Arthroscopic Posterior Capsulorrhaphy
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Table 40-27
Arthroscopic Posterior Capsulorrhaphy
Preoperative Planning
  •  
    Same as for anterior arthroscopic capsulorrhaphy (discussed above)
  •  
    Custom external orthosis should be premade and fitted prior to surgery
X
Positioning.
The setup is identical for arthroscopic anterior stabilization as described above with the use of either beach-chair or lateral decubitus position. Again, we prefer a lateral decubitus position because we believe it allows more inferior and posterior visualization. 
Surgical Approach.
The surgical approach is similar to a standard arthroscopy with the notable exception that visualization, though it initially starts with posterior camera insertion, changes to anterior superior visualization through the rotator interval. In addition, the initial posterior camera position should start slightly more lateral to allow for the second inferior posterior cannula and a better angle for anchor placement. 
Technique
Posterior Capsulorrhaphy.
After switching to an anterior viewing portal, the posterior pathology can be identified which can involve labral detachments, labral tears, capsular tears at the labrum, an enlarged posteroinferior capsule, and chondral injury (Fig. 40-57). 
Figure 40-57
Anterior-superior view of a patulous posterior capsule in recurrent posterior instability.
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A larger cannula is needed to pass a curved suture passing device. The posterior glenoid is prepared with a burr, rasp, or shaver. If the labrum and capsule are detached, which is not typical, these both should be mobilized prior to repair and 3-5 anchors can be inserted sequentially starting at the 5 or 6 o’clock position (Fig. 40-58). 
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Figure 40-58
Diagram of posterior labral repair with anchors.
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In addition, a capsular plication can be performed to reduce redundancy of the posteroinferior capsule. First, a suture passing device is passed through the full thickness of the capsule at the 6 o’clock position. A second pass is made under the labrum to create a “pleat.” A monofilament suture is placed and can be used as a tie or shuttle for a no. 2 nonabsorbable braided suture. The suture is tied with the goal to decrease the posterior redundancy. The steps are repeated superiorly along the posterior capsule until the redundant capsule is sufficiently reduced and tightened (Fig. 40-59). 
Figure 40-59
A: Diagram showing the end result of plication of the glenohumeral capsule.
 
Anterior-superior view of (B) the passage of a monofilament suture, (C) the use of a suture passing device, and (D) the final posterior capsulorrhaphy.
Anterior-superior view of (B) the passage of a monofilament suture, (C) the use of a suture passing device, and (D) the final posterior capsulorrhaphy.
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Figure 40-59
A: Diagram showing the end result of plication of the glenohumeral capsule.
Anterior-superior view of (B) the passage of a monofilament suture, (C) the use of a suture passing device, and (D) the final posterior capsulorrhaphy.
Anterior-superior view of (B) the passage of a monofilament suture, (C) the use of a suture passing device, and (D) the final posterior capsulorrhaphy.
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Rotator Interval Closure.
The rotator interval can be closed in addition to the capsular plication if there is still remaining laxity or it is considerably widened. It is controversial, however, whether this procedure is necessary or helpful. Using a posterior viewing portal, a #2 nonabsorbable suture is introduced with a spinal needle just anterior to the supraspinatus through the SGHL (and CHL, though it is not identified). The suture is retrieved through the anterior cannula with a suture retrieving device that has been passed through the MGHL just above the subscapularis. A knot is tied outside the joint in the subacromial space (Fig. 40-60). 
Figure 40-60
A: Diagram showing the passage of suture for the (B) closure of the rotator interval.
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Postoperative Management.
The protocol is the same as that for an open capsulorrhaphy. 
Pitfalls and Solutions (Table 40-28)
 
Table 40-28
Arthroscopic Posterior Capsulorrhaphy
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Table 40-28
Arthroscopic Posterior Capsulorrhaphy
Potential Pitfalls and Solutions
Pitfalls Solutions
Undertightening Convert to open procedure if there is excessive laxity
Additional rotator interval closure
Unrecognized glenoid hypoplasia or erosion Preoperative CT and MRI
Convert to open bony procedure
Unrecognized labral tear (Kim lesion) Use of anchors instead of simple plication
Very thin posterior capsule Incorporate the infraspinatus in the repair
Unrecognized posterior HAGL HAGL repair open or arthroscopic
Unrecognized posterior bone loss Open bony augmentation
X
Outcomes.
The literature for arthroscopic posterior repairs is difficult to interpret because isolated labral repairs and capsular plication are often combined. In addition, although some series report symptoms of recurrence as a failure, others do not as patients have a decrease in the subjective sense of instability. 
Overall, however, these repairs have resulted in successful stabilization. Authors have reported good-to-excellent results in 75% to 97% of the patients at short to midterm follow up.11,37,174,193,214,275,286,318,363,368 Rates of recurrent instability in these studies have ranged from 0% to 25%.37,275,363 One recent study confirmed that frank posterior dislocations after surgery were very rare; however, clinically significant posterior subluxations may be more common.39,318 In this study, 11% of the patients failed clinical stability tests and 8% pursued revision surgery for persisting pain, instability, or decreased function.39 A contemporary study in 2008 by Savoie et al. reported recurrent instability in only 2/92 patients with a 97% success rate. With evolving techniques, the results continue to improve.318 
Posterior Bony Augmentation or Glenoid Osteotomy.
Posterior bony augmentation with or without glenoid osteotomy should be approached with caution given the high complication rate. Unlike anterior instability, the degree of bone loss or retroversion necessitating these procedures are based mainly on expert opinion rather than clinical or biomechanical reports. However, bone loss exceeding 25% or retroversion >20 degrees, are often used as indications for bone grafting or osteotomy, respectively. Failure of extensive nonoperative management and even previous attempts at surgery such as a posterior capsulorrhaphy, is often necessary before these bony procedures are considered. Preoperative planning with a CT to determine bone loss and retroversion is mandatory. 
Preoperative Planning (Table 40-29)
 
Table 40-29
Open Posterior Bony Augmentation or Glenoid Osteotomy
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Table 40-29
Open Posterior Bony Augmentation or Glenoid Osteotomy
Preoperative Planning
  •  
    Same as open capsular shift
  •  
    Prone or lateral position should be considered for the use of iliac graft (vs. scapular spine)
  •  
    Small or large fragment set and power equipment
  •  
    Sharp osteotomes
X
Positioning.
Prone positioning with exposure of the iliac crest works well; however, lateral decubitus or beach-chair positioning can be used as described above. We favor a lateral position on a full-body bean bag. 
Surgical Approach.
A standard posterior approach is used as described above for a posterior capsulorrhaphy. 
Technique
Bone Augmentation.
The joint is exposed in the same manner as a posterior capsulorrhaphy with a transverse midcapsular incision. However, with bony augmentation, a vertical capsular incision should be made just lateral to the glenoid to both allow exposure to the posterior glenoid and to allow for enough capsule to repair to the posterior part of the bone block (intra-articular bone block) or to allow a capsular shift to the native glenoid with anchors (extra-articular bone block). We prefer an extra-articular bone block with a capsular shift. A 3- × 2- × 1-cm bone graft is obtained from the posterior iliac crest. The suprascapular nerve needs to be identified and protected as it lies only 1 to 2 cm medial to the glenoid rim. The posterior glenoid neck is prepared with a burr or rasp and the corticocancellous graft is placed with two lag screws. We prefer 3.5 partially threaded screws. It is critical that the graft does not overlap laterally. We then use three double-loaded anchors at the glenoid-graft margin to perform a capsular shift overlapping the capsular flaps as described above. 
Opening-Wedge Glenoid Osteotomy.
The joint is exposed similar to the capsular shift as described above with the vertical capsular incision on the glenoid side. It is important to leave a medial capsular flap as anchors cannot be used with the osteotomy for the capsular shift. An opening wedge osteotomy is performed at the posterior scapular neck. The opening wedge can be stabilized with a bone graft from the iliac crest or scapular spine. Surgical exposure of the scapular neck must be performed with caution as the suprascapular nerve lies in close proximity and is susceptible to injury during the procedure (Fig. 40-61). 
Figure 40-61
Posterior glenoid osteotomy.
 
A: An osteotome is placed in the joint to use as a parallel guide. A second osteotome is then used to begin the osteotomy. B: The osteotome is advanced approximately 90% the distance across the glenoid, being sure to leave an anterior hinge of bone. C: The osteotome is removed. D: The osteotomy is then bone grafted to maintain the desired change in version. E: The posterior capsule and infraspinatus are repaired. F: Note the change in version which is maintained by the bone graft.
A: An osteotome is placed in the joint to use as a parallel guide. A second osteotome is then used to begin the osteotomy. B: The osteotome is advanced approximately 90% the distance across the glenoid, being sure to leave an anterior hinge of bone. C: The osteotome is removed. D: The osteotomy is then bone grafted to maintain the desired change in version. E: The posterior capsule and infraspinatus are repaired. F: Note the change in version which is maintained by the bone graft.
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Figure 40-61
Posterior glenoid osteotomy.
A: An osteotome is placed in the joint to use as a parallel guide. A second osteotome is then used to begin the osteotomy. B: The osteotome is advanced approximately 90% the distance across the glenoid, being sure to leave an anterior hinge of bone. C: The osteotome is removed. D: The osteotomy is then bone grafted to maintain the desired change in version. E: The posterior capsule and infraspinatus are repaired. F: Note the change in version which is maintained by the bone graft.
A: An osteotome is placed in the joint to use as a parallel guide. A second osteotome is then used to begin the osteotomy. B: The osteotome is advanced approximately 90% the distance across the glenoid, being sure to leave an anterior hinge of bone. C: The osteotome is removed. D: The osteotomy is then bone grafted to maintain the desired change in version. E: The posterior capsule and infraspinatus are repaired. F: Note the change in version which is maintained by the bone graft.
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Before performing the osteotomy, a straight blunt instrument is inserted into the joint so that it rests on the anterior and posterior glenoid rim to fully understand the version. The osteotomy is made approximately 1 cm from the glenoid rim, where a drill can be used to determine width of the glenoid and to help guide the direction of the osteotome. A sharp wide osteotome or oscillating saw is then advanced parallel to the blunt instrument, but should not exit anteriorly. The bone is gently opened laterally to create an opening wedge osteotomy, hinging on the intact anterior cortex. An 8- × 30-mm bone graft placed firmly holds the wedge open. Screws are typically not needed. A posterior capsular shift is performed without anchors. 
Postoperative Management.
The standard posterior capsulorrhaphy protocol is used. 
Pitfalls and Solutions (Table 40-30)
 
Table 40-30
Open Posterior Bony Augmentation or Glenoid Osteotomy
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Table 40-30
Open Posterior Bony Augmentation or Glenoid Osteotomy
Potential Pitfalls and Solutions
Pitfalls Solutions
Suprascapular nerve injury Identify the nerve
Anterior coracoid abutment Avoid excessive external rotation during capsular shift
Violating anterior cortex Use drill bit to measure depth
Avoid lateral overhang of bone block Use temporary K-wires to judge graft placement
Intra-articular fracture Place K-wire or drill bit parallel to joint to guide osteotome
Limited capsular tissue for shift Vertical capsular incision 5 mm lateral to glenoid
X
Outcomes.
Case series of glenoid osteotomy and bone block procedures have mostly produced only satisfactory or poor results.22 Rates of recurrent instability after the procedures have been reported to be between 12% and 50%.95,103,122 In addition, these procedures are also associated with a variety of complications including anterior subluxation or instability, coracoid impingement, glenohumeral arthrosis, and intra-articular glenoid fracture.95,103,122 Graichen et al. reported unusually good results in 82% of their 32 patients who were treated with an osteotomy procedure.103 However, Meuffels et al.217 in 2010 showed extremely poor long-term results of a bone-block procedure with nearly half of the 11 patients having regretted their decision for surgery. Based on this data and our experience we believe there is a very limited role for this procedure. 

Multidirectional Instability

Nonoperative Treatment

Indications and Contraindications.
As discussed above, there is no one single pathologic lesion that leads to MDI. Instead, many have hypothesized that the observed abnormalities of the static stabilizers (redundant inferior capsule and rotator interval) put an increased burden on the dynamic stabilizers (the rotator cuff, the shoulder girdle musculature) that may fail with an acute traumatic event or repetitive microtrauma. A number of observations support this concept including glenohumeral proprioceptive deficits as well as abnormal coordination of muscle contraction in MDI. The result is scapular dyskinesis, weakness, pain, and ultimately instability. 
Nonoperative treatment, therefore, focuses on improving the coordination of the dynamic stabilizers to improve the scapulothoracic motion, to strengthen the rotator cuff, and to improve the glenohumeral proprioception. All patients diagnosed with MDI should have a physical therapy program for a minimum of 6 months before surgical intervention is considered. There is generally no contraindication to this strategy. 
Outcomes.
A number of studies have shown good success with a strengthening protocol for MDI. Burkhead and Rockwood,46 for instance, found that 80% of patients with atraumatic shoulder instability were successfully treated with a specific set of exercises to strengthen the shoulder musculature. Patients with a traumatic etiology, however, fared poorly with rehabilitation. This and other studies indicate that patients who do respond to therapy, demonstrated improvements within 3 months.226 
On the other hand, a recent study by Misamore et al.226 found that the long-term outcomes of young athletic patients with MDI treated with rehabilitation was poor: more than half did not respond. Therefore, if physical rehabilitation does not provide adequate improvement, patients often require surgical repair, specifically with an inferior capsular shift procedure.12,59 

Operative Treatment

Indications and Contraindications.
The nuances in establishing a clear diagnosis of MDI has contributed to the lack of consensus for the indications of surgical management. Much of this difficulty comes from the fact that patients may have a primary element of instability in one, two, or all three directions (inferior, posterior, or anterior). The treatment corresponds with the pathology. 
Most surgeons do agree, however, that the primary treatment for patients with atraumatic MDI instability should be nonoperative with a shoulder rehabilitation program. Operative treatment is indicated only with failure of this program after 6 months or the rare acute traumatic form of MDI. Psychogenic instability (i.e., habitual dislocators) is a contraindication for surgery as well as patients who have demonstrated noncompliant behavior with the requisite nonoperative treatment. Some surgeons feel Ehlers–Danlos or other connective tissue disease is a relative contraindication with a high surgical failure rate. Allograft tissue should be considered to supplement the repair, if performed (Table 40-31). 
 
Table 40-31
Multidirectional Instability
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Table 40-31
Multidirectional Instability
Operative Treatment
Indications Contraindications
Failed nonoperative structured rehabilitation program after 6 mos Psychogenic instability
Acute traumatic MDI with pan-labral pathology Inability to comply with postoperative therapy
Connective tissue disorder unless repair is augmented with allograft
X
Open Capsulorrhaphy.
Once the decision for an operative stabilization has been established, the procedure may be performed arthroscopically or as an open procedure. Often referred to as an “inferior capsular shift,” the procedure is designed to reduce the capsular volume on the side of the greatest instability as well as inferiorly and the opposite side. Therefore, open procedures are performed from either an anterior or posterior approach based on the pathology. Some surgeons preferentially utilize an anterior approach, because the capsule is thicker and it allows access to the rotator interval for further imbrication if necessary. 
The “gold standard” for surgical management of MDI instability has been open stabilization, though this is rapidly changing with improved arthroscopic skill and techniques. 
Deciding on a primary anterior or posterior approach (and capsulorrhaphy) is difficult. This decision should be based on the direction of greatest instability as ascertained from the history and physical examination. The examination with the patient under anesthesia can also provide insight, though, this rarely changes the operative approach. 
Surgical Planning and Technique.
Both the open anterior and posterior capsular shift techniques have been described above in detail. The key for both these procedures in the treatment of MDI is the placement of the vertical capsular incision. We prefer a humeral based incision for both the anterior and posterior shifts because we feel inferior redundancy is best eliminated with this technique. 
Postoperative Care.
Postoperative rehabilitation is slower for patients with MDI. Following surgical stabilization, the involved shoulder is immobilized in a sling for approximately 6 weeks. Passive motion is instituted at 4 weeks after the surgery. The limits of motion may vary depending on the stability of the repair. Shortly after the procedure, however, flexion, and external rotation are typically limited to 90 and 30 degrees, respectively. These limits are gradually increased to gain near full motion by 8 to 10 weeks. Upon removal of immobilization, active motion is instituted. Active strengthening exercises may be started by 10 to 12 weeks after the procedure. Patients are typically allowed full use of their shoulder by 6 months after the procedure; however, participation in high-demand activities and contact sports is deferred for at least 9 months in most patients. 
Pitfalls and Solutions (Table 40-32)
 
Table 40-32
Anterior Approach for Inferior Capsulorrhaphy
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Table 40-32
Anterior Approach for Inferior Capsulorrhaphy
Potential Pitfalls and Solutions
Pitfalls Solutions
Axillary nerve injury Identification of the nerve
Protection with blunt retractors prior to capsulotomy
Inadequate inferior release Release inferior subscapularis if exposure is inadequate
Release to the posterior-inferior quadrant
Subscapularis failure Attempt to preserve inferior tendon
Release at the tendon and not near the muscular–tendon junction
Posterior instability Repair with 30 degrees of abduction and external rotation
Missed labral tears Examine inside the joint
X
Outcomes.
There are a few reports describing the outcome of surgical treatment of MDI and they are inherently confounded by the lack of consensus on a definition and the variability of patient inclusion. Nonetheless, the few published reports show a high level of satisfaction and limited recurrence for open anterior stabilizations. Biomechanical analysis of the inferior capsular shift demonstrated near normal glenohumeral mechanics and contact pressures implying a low risk of long-term arthrosis.351 
Neer and Foster reported good or excellent results in 78% of their 40 patients, with only one patient developing recurrent instability. Several subsequent studies have reported comparable findings with good-to-excellent results in over 90% of patients and recurrent instability in less than 10%.12,59 Importantly, when the procedure is performed in a revision setting, the outcomes are less impressive. 
Other studies utilized either an anterior or posterior approach based on the primary degree of instability. The results of these methods are equally satisfactory with good-to-excellent results in 85% to 94% of the patients,54,117,207,269,334 with the rate of recurrent instability relatively low in two studies (4% to 9%). One study, however, reported recurrent instability in 26% of the patients, but with most of the failures occurring early—potentially pointing to a technical issue.117 
Arthroscopic Capsulorrhaphy.
Arthroscopic treatment of MDI has the advantage of evaluating the entire joint for other pathology and for having access to both the anterior and posterior sides. In addition, less trauma is created to the surrounding tissue. However, some have argued that a less extensive shift is possible arthroscopically because the technique is typically glenoid based where there is less tissue to mobilize compared to the humeral-based open shift. 
Preoperative Planning (Table 40-33)
 
Table 40-33
Arthroscopic Capsulorrhaphy for MDI
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Table 40-33
Arthroscopic Capsulorrhaphy for MDI
Preoperative Planning
  •  
    Same as the arthroscopic setup described above for a posterior capsulorrhaphy
  •  
    Small glenoid anchors (2.4–3.0 mm)
  •  
    Both 5 and 8 mm cannulas will be used. The large cannula is needed for passage of a suture-passing device
X
Positioning.
Either the lateral or beach-chair position can be used. 
Technique.
An examination under anesthesia should be performed to confirm the diagnosis and primary direction of instability. A diagnostic arthroscopy begins with a standard posterior portal. Pathology should be identified with specific attention paid to laxity and the quality of tissue of the inferior pouch, the rotator interval, the labrum and both the anterior and posterior capsules both on the glenoid and humeral sides. The posterior capsule can be extremely thin and difficult to effectively mobilize. Most patients with atraumatic MDI do not have a capsulolabral detachment, but this pathology can sometimes be seen. The most common finding is the presence of redundant anterior, inferior, and posterior capsules. 
Similar to the arthroscopic posterior capsulorrhaphy described above, the lax capsule is managed with plication sutures or bioabsorbable anchor placement. For arthroscopic capsulorrhaphy in the anterior region, the arthroscope is typically placed through a posterior portal whereas the instruments and the sutures are managed through anterior portals. In contrast, for posterior capsulorrhaphy, the arthroscope is placed through the anterior portal and the instruments and the sutures are managed through posterior portals. 
The capsulorrhaphy is performed with a curved suture passer that is passed through the full thickness of the capsule at the 6 o’clock position. A second pass is made under to the labrum to create a “pleat.” A monofilament suture is placed and can be used as a tie or shuttle for a #2 nonabsorbable braided suture. The suture is tied with the knot away from the glenoid with the goal to decrease the capsular redundancy. It is important for the first stitch and its subsequent superior shift to be adequate to reduce the inferior laxity. It is difficult to correct capsular laxity if this shift is inadequate (Fig. 40-62). 
Figure 40-62
Diagram showing anterior and posterior arthroscopic glenoid-based capsulorrhaphy for MDI.
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The steps are repeated superiorly along the anterior and posterior capsules until the redundant capsule is sufficiently reduced and tightened. If the posterior capsule is thin, the infraspinatus can be incorporated. This can be done by passing a spinal needle through the tendon and passing a suture or suture shuttle to be retrieved by the suture passer placed through the capsule. The cannula is pulled back out of the joint into the subacromial space. A crochet hook is then placed through the cannula to blindly grab the suture passed through the tendon. The suture is then tied blindly in the subacromial space and the amount of capsular tightening is viewed inside the joint. 
Rotator interval closure may be added to capsular plication in the setting of MDI instability to further limit humeral head translation. The technique is described above in the arthroscopic posterior capsulorrhaphy section (Fig. 40-60). 
Postoperative Care.
The postoperative protocol is similar to the open repair, but is individualized based on the primary direction of instability. If the primary laxity and repair is anterior, the protocol for the open anterior approach for MDI is used. Otherwise the posterior instability protocol is used with a custom orthosis in neutral rotation. 
Pitfalls and Solutions (Table 40-34)
 
Table 40-34
Arthroscopic Capsulorrhaphy for MDI
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Table 40-34
Arthroscopic Capsulorrhaphy for MDI
Potential Pitfalls and Solutions
Pitfalls Solutions
Thin posterior capsule Incorporate infraspinatus tendon
Use a bioabsorable anchor
Inadequate inferior exposure Lateral position facilitates this exposure
Inadequate shift A large initial superior shift at the 6 o’clock position is key
X
Outcomes.
Only short-term follow-up studies are available for arthroscopic repair techniques.89,90,213,345 Nonetheless, the results are very good and appear comparable to open repairs. Treacy and Savoie had 88% good-to-excellent results and 12% recurrent instability using the suture technique described above.345 Similarly, Gartsman et al. reported good-to-excellent results in 94% of patients with 35 months of follow-up.90 These and other reports confirm this success rate with a recurrent instability generally less than 10%.13,175 

Complications of Glenohumeral Instability (Table 40-35)

 
Table 40-35
Glenohumeral Instability
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Table 40-35
Glenohumeral Instability
Complications
Incorrect diagnosis
Infection
Nerve injury
Hardware complications
Recurrence of instability
Loss of motion
Capsulorrhaphy arthropathy
Subscapularis failure
X

Incorrect Diagnosis of Glenohumeral Instability

Based on the literature, approximately 90% of instability is traumatic in the anterior direction.254,324,374 Therefore, few surgeons will encounter atraumatic anterior, MDI or posterior instability regularly. Recognition of these often subtle presentations requires an understanding of the evolving theories explaining or classifying these diagnoses. For example, Hawkins and Hawkins reported on a small series of 46 patients in their referral practice with continuing difficulty after anterior instability procedures. They determine that 12 patients had unrecognized MDI or posterior instability.123 Other reports have found similar findings.211 
Other traumatic pathologies may also be missed leading to the incorrect procedure. Commonly missed pathologies include HAGL lesions,367 rotator interval defects, residual capsular laxity, and bone loss for both the glenoid and humeral head.44,111,367 Though, relatively uncommon, failure to recognize these pathologies and to subsequently treat the patient simply with a Bankart-type repair would likely lead to continued instability. 

Infection

Regardless of the specific surgical approach, infection is an uncommon complication following a shoulder stabilization procedure. Review of all anterior shoulder stabilizations performed at the Mayo Clinic between 1980 and 2001 identified only six infections.333 Similarly, a review of the recent literature on arthroscopic shoulder stabilizations has demonstrated an infection rate less than 0.25%.111,171,363 
Recent attention has been given to prevalence of infection with the bacteria Proprionibacterium acnes, which is normal skin flora prevalent in the axilla.261 It has been noted to lead to both indolent and grossly symptomatic infections in both open and arthroscopic shoulder procedures.155,184 Suspicion needs to be high to identify the infection with a combination of lab values, aspiration, and extended culture times (10 to 14 days). Certain skin preparations and antibiotics are also better in preventing the infection including chlorhexidine and clindamycin, respectively.155,316 

Nerve Injuries

For arthroscopic procedures, nerve dysfunction of almost all major upper extremity nerves has been reported related to the traction or compression by the arm holder, fluid distention of the joint, and fluid extravasation. Direct nerve injury to the axillary or musculocutaneous nerve is exceedingly rare. Almost all nerve injuries are neurapraxias that resolve with time. In the modern literature, the incidence of neurologic dysfunction, mild or otherwise, has been reported to be approximately 3%.90,102,326 
For open procedures, nerve dysfunction has been reported to be as high as 8.2% in 282 patients who underwent an open anterior stabilization surgery.130 Though most are neurapraxias, it points to the increased risk open surgery incurs because of the proximity of both the musculocutaneous and the axillary nerves. The musculocutaneous nerve is likely to be injured because of excessive retraction on the conjoined tendon especially with a self-retaining retractor. With the Latarjet procedure, both the axillary and musculocutaneous nerves are exposed and must be protected by an anterior humeral neck retractor. Shah et al.321 reported a 10% nerve injury rate with this procedure, though most injuries resolved. Injury to the axillary nerve can occur during dissection of the shoulder capsule in the anterior inferior quadrant of the glenoid. Though traction is often the culprit, direct injury to the axillary nerve has been reported, and the likelihood of a spontaneous recovery is low.201 Last, with anterior bone grafting procedures, the suprascapular nerve can be injured on the posterior side of the glenoid with placement of screws. Injury can be avoided with low placement of the graft and the use of oscillation when drilling.204 

Hardware Complications

Hardware complications can be seen with specific techniques such as the Latarjet (Fig. 40-63).373 However, small glenoid suture anchors are universal and are used for open and arthroscopic procedures for all directions of instability. Generally few complications are reported, but a few points should be noted. Metallic suture anchors should not be used in the glenoid because of the risk of migration, prominence, and chondral injury. Bioabsorbable suture anchors decrease the risk of hardware-related complications, but foreign body reaction has been reported.43 Attention to countersinking the anchors below subchondral bone, and not just the cartilage, is critical as chondral injury can still occur. 
Figure 40-63
Failed Latarjet with loosening of the screws because of graft resorption and recurrent dislocation leading to humeral head erosion on the screw heads.
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Recurrence of Instability

Anterior Instability

The recurrence of instability is one of the most common complications after any instability procedure. However, the incidence varies dramatically based on the technique and reasons for surgery. With modern techniques, the recurrence rates for both arthroscopic and open techniques are similar, ranging from 0% to 20%. Some believe open surgery still has a slightly lower rate of recurrence, especially with certain specific risk factors. 
The reason for failure varies broadly to include inherent risk factors, incorrect diagnosis, incorrect surgical procedure or technical error, and unanticipated event such as repeat trauma. 

Posterior Instability

Generally speaking, the results of posterior stabilization are inferior to those of anterior repair. The modern literature is promising and indicates a failure rate of about 0% to 23% with arthroscopic procedures having generally better results.37,268,363,368 This can be attributed to a number of factors including a less clear diagnosis with significant overlap with MDI, the absence of an “essential” pathologic lesion to treat, and less experience by surgeons relative to anterior instability. Recurrence rates are certainly higher when previous surgery has been performed, but the common trend in the literature is failure to either address the inferior laxity or a deficient rotator interval.275,281 Patients with posterior bone-block procedures have significantly worse outcomes with recurrence rates as high as 40%.95,217 

Multidirectional Instability

The most recognized problem seen with MDI is the recurrence of instability; however, the rates for both open and arthroscopic repairs are acceptable. For open procedures, Neer and Foster, Pollock et al., and Bak et al. found a recurrence rate of approximately 10% for open procedures.12,233,269 Similarly, for arthroscopic procedures, a number of investigators have found satisfactory rates with comparable rates of recurrence.90 

Loss of Motion

Open anatomic capsulolabral reconstruction procedures generally lead to a greater degree of stiffness than arthroscopic repairs.75 Some of this stiffness is attributed to the relatively increased surgical trauma of open repairs as well as the increased ability to tighten the capsule. Stiffness for anterior arthroscopic repairs is reported to be 10% to 15% though the loss of motion is often less than 10 degrees, typically in external rotation.75,106 Interestingly, the Latarjet procedure, though often considered motion limiting, does not lead to greater loss or motion compared to open Bankart repairs.320 
Other common causes of stiffness following shoulder stabilization surgery include prolonged immobilization and poor compliance with the rehabilitation program. It is important to initiate a rehabilitation program that focuses on motion as soon as possible following the repair. The need for early motion, however, must be balanced against placing the underlying surgical construct at risk for failure. Three to four weeks of immobilization has been recommended by a number of investigations.171,172 

Capsulorrhaphy Arthropathy

An overtightening of the anterior capsule leads to contracture and abnormal glenohumeral mechanics.124 In turn, the altered mechanics lead to degenerative changes characterized by glenohumeral arthritis, eccentric posterior glenoid wear, or even posterior subluxation (Fig. 40-64). Most patients present late when advanced arthritic change necessitates an arthroplasty. Bigliani reported on a group of such patients who required arthroplasty at a mean of 16 years after their index instability surgery.29 These arthroplasties are particularly difficult because of the internal rotation contractures from scarred anterior soft tissues and posterior glenoid wear. The outcomes for arthroplasty for capsulorrhaphy arthropathy, though good, are worse than for osteoarthritis and revisions are common given the younger age and active nature of the patients. In Bigliani’s series 13 (77%) patients had satisfactory results, whereas 4 (33%) had poor results related to pain, limited motion, and subscapularis failure. 
Figure 40-64
Capsulorrhaphy arthropathy after previous instability procedure.
 
AP (A) and axillary (B) radiographs reveal large osteophytes and posterior subluxation with loss of joint space.
AP (A) and axillary (B) radiographs reveal large osteophytes and posterior subluxation with loss of joint space.
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Figure 40-64
Capsulorrhaphy arthropathy after previous instability procedure.
AP (A) and axillary (B) radiographs reveal large osteophytes and posterior subluxation with loss of joint space.
AP (A) and axillary (B) radiographs reveal large osteophytes and posterior subluxation with loss of joint space.
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Subcapularis Failure

There is little or no risk of subscapularis failure in an arthroscopic repair as the tendinous insertion is not violated. However, in open procedures, the muscle and tendon are often taken down completely or are significantly violated. Sachs et al. reported on 30 patients with open Bankart repairs: Seven patients had an incompetent subscapularis with four having poor outcomes. Limiting early rehabilitation, especially external rotation, is key.313 Management of a failed subscapularis is difficult as direct repair is often impossible. A pectoralis major muscle transfer can improve function, but there are some data that it might exacerbate instability as the direction of pull is relatively anterior compared to the normal subscapularis.73 

Author’s Preferred Treatment for Glenohumeral Instability (Figs. 40-6540-67)

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Figure 40-65
Anterior instability.
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Figure 40-66
Posterior instability.
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Figure 40-67
Multidirectional instability.
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Controversies and Future Directions Related to Glenohumeral Instability

Treatment After Initial Traumatic Anterior Dislocation

We can currently treat glenohumeral instability arthroscopically with limited complications and low recurrence rates. Therefore, the optimal treatment of patients after an initial traumatic anterior dislocation is controversial. Early treatment from an acute injury is technically simpler when the tissue is pliable and acute tissue injury enhances healing. For patients with low rates of recurrent instability after an initial dislocation (such as older patients) (Table 40-2) the small risks of surgery may outweigh the benefits. Conversely, men less than 20 years of age with recurrence rates as high as 84% in the first 2 years may benefit from primary arthroscopic stabilization.299,300 
A number of prospective observational studies and trials, as discussed above, have given us excellent data about the accurate risks of recurrent instability and complications for both operative and nonoperative treatment after primary traumatic anterior instability.63,187,299,300 This data combined with decision-analysis modeling can help us decide the best treatment for individual patients based on their risk aversity. A recent article by Bishop et al.30 looks at expected-value analysis to maximize patient outcome based on objective methods of determining patient values. They found that patients with a high rate of recurrent instability (i.e., young men) would benefit from stabilization after only one dislocation. Older patients and risk-averse patients would not. 

Management of Bone Loss

Bone loss on both the glenoid and humeral side is increasingly recognized as a major contributor to recurrent instability and surgical treatment failure. Numerous methodologies of measuring glenoid bone loss have been created, but none are universal and the indications for treatment and the types of treatments have been evolving. There has been a renewed interest in bony procedures such as the Latarjet and even the use of allograft for both the glenoid and certain Hill–Sachs defects. However, there are a certain number of unknown questions that exist including: 
  1.  
    When does a Hill–Sachs lesion need to be treated and how does glenoid bone loss effect this equation?
  2.  
    When is an open capsulorrhaphy indicated versus a bony procedure?
  3.  
    Given the high complication rates with a Latarjet, is there value in an initial arthroscopic approach for borderline cases or does this worsen outcomes if a bony procedure is subsequently performed?
  4.  
    Should the bone block be intra or extra-articular?
Many of these questions have preliminary answers, but none are fully elucidated. 

The Role of Open Capsulorrhaphy

Last, I believe we are at an inflection point in terms of the techniques with which we treat instability. With the amazing arthroscopic skills of some, fewer surgeons performing open capsulorrhaphies, and a generation of new surgeons who may never have seen an open capsulorrhaphy, the way we manage instability is likely forever changed. The data seems to imply that arthroscopic procedures are as good or better than open procedures for most cases. The risks are significantly lower as well. Besides open bony procedures, open capsulorraphies, much like Putti–Platt, will likely not be addressed significantly in future Rockwood editions to come. This may not be a good thing, but inevitable, nonetheless. 

References

1.
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