Chapter 41: Acromioclavicular Joint Injuries

Cory Edgar, Anthony DeGiacomo, Mark J. Lemos, Augustus D. Mazzocca

Chapter Outline

Introduction to Acromioclavicular Joint Injuries

Injuries to the acromioclavicular (AC) joint represent a spectrum of soft tissue disruptions that can result in mild, transient pain about the joint to significant displacement, chronic pain, and changes in shoulder biomechanics resulting in long-term disability. These injures most commonly occur in male patients <30 years and are associated with contact sports or athletic activity in which a direct blow to the lateral aspect of the shoulder occurs. The contact or collision athlete represents a “high-risk” individual, especially those who play sports like football, rugby, and hockey.38,43,75,116 The management of these injuries has been discussed in academic forums since the time of Hippocrates and Galen, but there still appears to be no consensus regarding when operative management is necessary and which procedure produces the best functional outcome with the least morbidity.88,97,120,127,136,141 This chapter will focus on the traumatic aspects of AC disorders through an in depth review of the local anatomy and applied biomechanics of the joint. A classification based on the spectrum of injury is presented in addition to nonsurgical and surgical treatment options. However, there remains a lack of high-quality comparative studies from which treatment guidelines can be made and therefore an overview of approaches is presented. 
From a historical perspective, the treatment of AC joint dislocations has been a subject of controversy from the earliest medical writings. For example, Hippocrates1 (460–377 BC) wrote: 
 

“Physicians are particularly liable to be deceived in this accident (for as the separated bone protrudes, the top of the shoulder appears low and hollow), so that they may prepare as if for dislocation of the shoulder; for I have known many physicians otherwise not expert at the art who have done much mischief by attempting to reduce shoulders, thus supposing it as a case of dislocation.”

 
Galen1 (129–199 AD) had obviously paid close attention to Hippocrates, because he diagnosed his own AC dislocation received from wrestling in the Palaestra. This famous physician of the Greco-Roman period treated himself in the manner of Hippocrates (tight bandages to hold the projecting clavicle down while keeping the arm elevated). He abandoned the treatment after only a few days because it was so uncomfortable. It is appropriate that one of the earliest reported cases in the literature was related to sports, because athletic participation is certainly one of the most common causes of AC dislocations and the story highlights the low compliance rate of shoulder bracing. 
The surgical treatment of AC joint injuries has evolved with our understanding of the local anatomy and the biomechanics of the joint, and demonstrates a clear historical progression. Samuel Cooper127 is given credit for the initial report of the surgical management of a displaced, painful AC joint dislocation in 1861. In 1917, Cadenat21 described transfer of the coracoacromial ligament, a procedure later popularized by Weaver and Dunn.161 Multiple studies have been published using variations of this technique clouding the literature of its true efficacy. Interestingly, over the last 10 to 15 years there has been an increase in the number of publications of surgical treatment of AC joint dislocations with repairs or reconstruction procedures (Fig. 41-1). Presumably, it is related to a better understanding of the important anatomy. The rapid progression of orthopedic implant technology has also led to the application of improved surgical techniques and strategies. This has dramatically changed the way these injuries are surgically managed. Open reconstruction techniques have a common goal to reduce the AC joint to an anatomic position. This can be accomplished using traditional methods that provide a very rigid construct or a more anatomic approach, in which the goal is to provide a reconstruction that addresses the three-dimensional function of the AC joint complex. 
Figure 41-1
Trends in reported surgical techniques to repair or reconstruct AC joint dislocations.
 
(From Beitzel K, Cote MP, Apostolakos J, et al. Current concepts in the treatment of acromioclavicular joint dislocations. Arthroscopy. 2013;29(2):387–397.)
(From Beitzel K, Cote MP, Apostolakos J, et al. Current concepts in the treatment of acromioclavicular joint dislocations. Arthroscopy. 2013;29(2):387–397.)
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Figure 41-1
Trends in reported surgical techniques to repair or reconstruct AC joint dislocations.
(From Beitzel K, Cote MP, Apostolakos J, et al. Current concepts in the treatment of acromioclavicular joint dislocations. Arthroscopy. 2013;29(2):387–397.)
(From Beitzel K, Cote MP, Apostolakos J, et al. Current concepts in the treatment of acromioclavicular joint dislocations. Arthroscopy. 2013;29(2):387–397.)
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It is clear that a “gold standard” for surgical stabilization of acute, painful AC joint dislocations has yet to be established. 

Assessment of Acromioclavicular Joint Injuries

Mechanisms of Injury of Acromioclavicular Joint Injury

There are numerous ways in which trauma to the shoulder girdle can result in AC joint injury. As with any traumatic injury the direction and magnitude of the force vector dictates the resultant injury pattern. Falling on an outstretched arm, locked in extension at the elbow, can drive the humeral head superior into the acromion typically resulting in low-grade AC joint injuries (Fig. 41-2). A medial directed force to the lateral shoulder that drives the acromion into and underneath the distal clavicle, as occurs, for example, when getting checked into the boards during a hockey game, can result in higher degrees of injury and subsequently more displacement.127 One of the more commonly described patterns involves falling or being tackled onto the lateral aspect of the shoulder with the arm in an adducted position which produces a compressive (medial) and shear (vertical) force across the joint. This typically produces a higher degree of displacement because the force is enough to both the AC and coracoclavicular (CC) ligaments (Fig. 41-2). One common misconception is the clavicle “elevates” superior to the acromion. In actuality the shoulder girdle is suspended from the axial skeleton by the AC joint complex (the specific anatomy of which will be discussed in the next section). The injury force which drives the acromion medially and downward produces a progressive injury pattern; first disruption of the AC ligaments, followed by disruption of the CC ligaments, and finally disruption of the fascia overlying the clavicle that connects the deltoid and trapezius muscle attachments.99 At this point, the upper extremity has lost its suspensory support from the clavicle and the scapula and associated glenohumeral articulation displaces inferiorly secondary to forces of gravity. Although there may be a slight upward displacement of the clavicle from the pull of the trapezius muscle, the characteristic anatomic feature is actually inferior displacement of the shoulder and arm. Because the weight of the arm is no longer suspended from the clavicle, there may be a slight upward pull by the trapezius muscle on the clavicle. However, the major deformity seen in complete AC dislocation is a downward displacement of the shoulder (Fig. 41-3). 
Figure 41-2
 
A: Most common position of injury; adducted arm with axial load to superior AC joint. B: Illustration of force directions that can cause displacement of the glenohumeral complex away from or into the AC suspensory complex causing injury to the ligaments; superior, inferior, and medial.
A: Most common position of injury; adducted arm with axial load to superior AC joint. B: Illustration of force directions that can cause displacement of the glenohumeral complex away from or into the AC suspensory complex causing injury to the ligaments; superior, inferior, and medial.
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Figure 41-2
A: Most common position of injury; adducted arm with axial load to superior AC joint. B: Illustration of force directions that can cause displacement of the glenohumeral complex away from or into the AC suspensory complex causing injury to the ligaments; superior, inferior, and medial.
A: Most common position of injury; adducted arm with axial load to superior AC joint. B: Illustration of force directions that can cause displacement of the glenohumeral complex away from or into the AC suspensory complex causing injury to the ligaments; superior, inferior, and medial.
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Figure 41-3
Radiograph example of Zanca view with bilateral AC joints visualized.
 
Note the displaced AC joint on the right. This view allows for measurement and comparison of CC distance from injured to uninjured side, note the CC distance measured on the left (uninjured side).
Note the displaced AC joint on the right. This view allows for measurement and comparison of CC distance from injured to uninjured side, note the CC distance measured on the left (uninjured side).
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Figure 41-3
Radiograph example of Zanca view with bilateral AC joints visualized.
Note the displaced AC joint on the right. This view allows for measurement and comparison of CC distance from injured to uninjured side, note the CC distance measured on the left (uninjured side).
Note the displaced AC joint on the right. This view allows for measurement and comparison of CC distance from injured to uninjured side, note the CC distance measured on the left (uninjured side).
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The mechanism of inferior dislocation of the clavicle under the coracoid is thought to be a very severe direct force onto the superior surface of the distal clavicle; along with abduction of the arm and retraction of the scapula,100,127 this type of AC joint dislocation is exceedingly rare. 

Associated Injuries with Acromioclavicular Joint Injury

Glenohumeral Intra-Articular Pathology

Only two studies have reported on the incidence of glenohumeral pathology documented with arthroscopy during the treatment of high-grade AC joint dislocations. In a series of 77 patients with grade III to V injuries, arthroscopic evaluation determined 18.2% had a superior labral anterior to posterior (SLAP) lesion, one patient had a complete tear of the supraspinatus and two patients had partial articular-sided cuff tears.152 Treatment consisted of debridement of the partial cuff tears and type I SLAP tears, but all additional pathology was surgically repaired. Pauly et al.117 noted a 15% (6/40) incidence of intra-articular pathology in their series of 40 consecutive patients undergoing arthroscopic-assisted reconstruction of grade III to V AC joint dislocations. They reported three patients with SLAP lesions and three patients with partial articular-sided cuff tears, usually in the supraspinatus. As there is overlapping innervation to this region of the shoulder through the lateral pectoral and suprascapular nerves it may be difficult for the patient to completely localize their pain.58 Currently there is no data to support getting a preoperative MRI arthrogram to aid in the diagnosis of a concomitant injury or surgical intervention to treat the pathology. 

Fractures

Any fracture that disrupts the CC ligaments and AC joint capsule/ligaments effectually disrupts the suspension of the upper limb in the same manner as a grade III or greater AC separation. The most common fracture pattern is the distal or lateral clavicle fracture that is discussed later in the chapter. Similarly the base or neck of the coracoid process can be fractured leaving the CC ligaments attached to the fracture fragment but presenting as a high-grade AC separation.78,80,85,160 Another uncommon combination is fracture of the clavicle shaft in conjunction with an AC joint separation, Wurtz et al.166 reported on four patients with a fracture of the middle third of the clavicle and dislocation of the AC joint. In three cases with grade IV AC separations the AC joint was treated with either a CC screw or Steinmann pins across the AC joint and the clavicle fracture treated nonoperatively. The final case was treated nonoperatively. Patients were followed from 1 to 3 years and excellent motion and function was reported. In a patient less than age 30, concomitant injury to the medial clavicular epiphysis has been reported that required open reduction at the epiphyseal fracture to facilitate reduction of a posterior AC joint dislocation.70,135,158 

Bipolar Injuries: AC and SC Joint Dislocations

An uncommon and frequently unrecognized injury to the sternoclavicular (SC) joint can occur in conjunction with AC joint dislocations and has been referred to as a “floating clavicle” or panclavicular dislocation. These bipolar injury patterns typically occur with high-energy trauma and may be associated with neurologic symptoms. All the reported cases describe anterior dislocation at the SC joint combined with a posterior dislocation of the AC joint.45,57,73,133,135 Conservative management is described with success in the older or lower demand patients.133 Techniques used to surgically treat these bipolar injuries have been varied. Bilateral (Balser) hook plates have recently been used with good success,135 but more traditional methods of open reduction with capsular repair and in some cases augmentation with Kirschner wires has also been reported with success.45,133 

Brachial Plexus Abnormalities

Meislin et al.101 have reported a patient who developed a brachial plexus neurapraxia 8 years after sustaining a type III AC separation. A patient responded well to CC stabilization. Brachial plexus injuries associated with AC separations are not common. Sturm and Perry,147 in a review of 59 patients with brachial plexus injuries, identified two patients with AC separations. 

Coracoclavicular Ossification

CC ossification has been referred to as both ossification and calcification. It is secondary to intrinsic healing response within this area following injury to the CC ligaments. This has been observed and described since the 1940s and has never been associated with increased pain or dysfunction.157 However, it is commonly observed radiographically in cases of chronic AC separations and often in cases with higher degrees of injury. The calcification can be formed heterotopically around the area of injury, or it can form a bridge between the coracoid and the clavicle. Usually, it has no effect on the functional outcome but must be removed to facilitate full reduction of the AC joint and CC distance at the time of operative intervention. 

Osteolysis of the Distal Clavicle

Osteolysis of the distal clavicle is a radiographic finding that may or may not be associated with significant symptoms of pain at the AC joint with cross-arm adduction and overhead lifting. Traumatic distal clavicle osteolysis can be associated with low-grade AC separations in which an extended inflammatory response or repeated injury occurs, leading to the osteolysis observed on radiographs. Madsen92 reported on seven patients with the complication known as posttraumatic osteolysis of the distal clavicle. He identified eight cases in the literature and seven of his own, all of which had some level of AC joint separation or repeated microtrauma to the area (i.e., pneumatic tool worker). Cahill22 reported on 46 patients who were athletes with traumatic distal clavicle osteolysis (typically from weight lifting). With histologic analysis, he and others described the intense osteoblastic activity of the subchondral bone from surgical specimens of these osteolytic patients.20,22,139 These observations confirmed the hypothesis that repeated microtrauma with a recurrent inflammatory process was part of the etiology. Additional microscopic studies have been reported by Murphy et al.109 and Madsen92 in which they describe demineralization, subchondral cysts, and erosion of the distal clavicle observed in pathology from intraoperative tissue samples. Griffiths and Glucksman62 performed a biopsy 8 months after injury that showed patches of necrotic and reactive woven bone. 
The radiographic findings are osteoporosis, osteolysis, and tapering of the distal clavicle. Usually, bony changes do not occur in the acromion. Changes usually occur only in the injured shoulder. If changes are noted in both shoulders, then other conditions should be considered, such as rheumatoid arthritis, hyperparathyroidism, and scleroderma. The differential diagnosis of a lesion in one shoulder should include Gorham’s massive osteolysis, gout, and a neoplasm such as multiple myeloma. The use of technetium bone scans and a 35-degree cephalic tilt radiographic view to help make the diagnosis has been reported to help determine the activity of the bone resorption process.22 

Scapulothoracic Dissociation

Scapulothoracic dissociation is a very rare but potentially devastating injury, especially if missed, that can occur through an AC separation.102 Scapulothoracic dissociations are characterized by lateral displacement of the scapula resulting in a traction injury to the neurovascular structures of the shoulder. In more significant lateral displacement the patient can present with a severe vascular injury and brachial plexus injury. Disruption of the shoulder girdle occurs through either a high-grade AC separation, a displaced clavicle fracture, or a SC disruption. Scapulothoracic dissociations are often clinically subtle injuries in a patient with a distraction injury to the shoulder. A head injury may mask the acute determination of neurovascular injury. Therefore, it is important to consider this injury in the “unexaminable” (i.e., unconscious, head injured) patient with significant trauma and a high-grade AC separation. In the examinable patient a complaint of chest pain or pain in the periscapular and perithoracic region should elicit a chest radiograph as part of the work up. Clinical examination demonstrates the AC deformity as well as marked tenderness in the periscapular and perithoracic region. An anteroposterior (AP) chest radiograph demonstrates an increased distance between the medial scapular border and the midline on the affected side compared with the unaffected side, as well as other signs of thoracic trauma such as a pleural effusion. Magnetic resonance imaging of the thorax demonstrates increased signal in the periscapular and perithoracic muscles in addition to intrathoracic pathology. 

Signs and Symptoms of Acromioclavicular Joint Injury

Clinical Presentation and History

As this injury is secondary to a traumatic event, the clinical history almost always involves a description of injury to the affected shoulder or upper extremity. As clinical deformity is a common finding and complaint, the patient should be examined, whenever possible, in the standing or sitting position to allow for accentuation of the deformity by gravity. Traditionally, a weighted stress view of the AC joint was performed in an attempt to create maximal distraction between the CC space and the AC joint. It is postulated that this maneuver allows indirect determination of the deltopectoral fascia integrity, therefore differentiating a type III injury from a type V. This has not been validated in any study using this technique in correlation with intraoperative findings. It is our opinion that this study does not increase the sensitivity of diagnosis, change the “grade” or classification of the AC joint injury, does not change treatment, and more importantly it is a very painful maneuver for the patient in an acute injury. Therefore we do not recommend its routine use. 
The mechanism for AC joint injuries and distal clavicle fractures is direct trauma, caused by a fall or blow with the arm in the adducted position. The subcutaneous position of the joint, makes observation of the deformity quite apparent and after the pain resolves it is one of the most common clinical complaints. It should be noted that indirect injury to the AC joint could occur by falling on an adducted outstretched hand or elbow which causes the humerus to translate superiorly and impact the acromion. 
The majority of AC joint injuries occurs in young to middle-aged males and is typically caused by a direct load to the lateral shoulder or a forced impaction of the humeral head superiorly into the acromion. The contact or collision athlete represents a “high-risk” individual and AC injuries are typically associated with sports like football, rugby, and hockey.38,43,75,127 A recent report estimated that AC joint injuries accounted for 4.5% of all injuries, but 32% of all shoulder injuries in a population of NCAA football players followed for 5 years.43 Interestingly, of the 748 injuries to the AC joint recorded, the vast majority (96%) were “low-grade” injuries, classified as type I or II sprains (according to the Rockwood classification system). Similar injury incidences were reported by Kaplan et al.,75 AC joint injuries accounted for 41% of the shoulder injuries reported when players at the NFL combines were asked to recall collegiate injuries that forced them to miss playing time. The incidence among hockey players is less well studied but the rates appear similar. In one study of Finnish hockey players followed for a season, 12% of the 755 injuries within the upper extremity reported to insurance providers were AC joint sprains.103 

Physical Examination

As with any shoulder examination, the patient should be completely exposed to allow for comparison with the uninjured shoulder. Commonly the patient describes pain originating from the anterior-superior aspect of the shoulder, but it may be challenging to localize to a specific structure as the source. It should be noted that the lateral pectoral nerve, which also provides sensation to the anterior aspect of the shoulder and glenohumeral joint, provides the innervation of the AC joint capsule (Fig. 41-4).58 Gerber et al.58 evaluated patterns of pain and found that irritation to the AC joint produced pain over the AC joint, the anterolateral neck, and in the region in the anterolateral deltoid. Stimulation within the subacromial space produced pain slightly more lateral, in the region of the lateral acromion and lateral deltoid muscle, but did not produce pain in the neck or trapezius region. 
Artist rendition view from superior looking down onto the AC joint with scapula below.
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Figure 41-4
Illustration representing the overlapping innervation to the AC joint and glenohumeral joint via the anterior lateral pectoral nerve and the posterior suprascapular nerve.
Artist rendition view from superior looking down onto the AC joint with scapula below.
Artist rendition view from superior looking down onto the AC joint with scapula below.
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The clinical triad of point tenderness at the AC joint, pain exacerbation with cross-arm adduction, and relief of symptoms by injection of a local anesthetic agent confirm injury to the AC joint. The cross-arm adduction test is performed with the arm elevated to 90 degrees and then adducted across the chest with the elbow bent at approximately 90 degrees. A positive test produces pain specifically at the AC joint. The reason that the cross-arm adduction test causes pain at the AC joint specifically is because of the compression across the AC joint with that motion. Walton et al.159 recently documented the accuracy of clinical tests for determining whether pain is caused by AC joint injury. They describe using the Paxinos test (thumb pressure at the posterior AC joint) and a bone scan to accurately assess pain secondary to AC joint pathology. MRI scanning has been shown to be just as accurate.146 O’Brien et al.115 recommended the active compression test for diagnosis of AC joint abnormalities and labral pathology. They reported 88% (55/62) of patients who had pain in the AC joint with the active compression test demonstrated abnormalities in the joint at the time of operative treatment, or had radiographic evidence of AC injury. The O’Brien test may be particularly helpful when attempting to differentiate symptoms of AC joint arthrosis from intra-articular lesions, especially those of the superior glenoid labrum. The test is performed with the arm elevated to 90 degrees, elbow in extension, adduction of 10 to 15 degrees, and a maximum pronation of the forearm with obligate internal rotation of the arm. The examiner applies a downward force resisted by the patient. Symptoms referred to the top of the shoulder and confirmed by examiner palpation suggest AC joint pathology. Localization of pain more distal to the rotator interval or anterior aspect of the shoulder suggests possible labral or biceps injury. The O’Brien maneuver, to determine superior labral pathology in isolation, is difficult to apply given its reported sensitivity is 63% and the specificity 73%.58 Therefore, clinical history, exam, imaging findings or pathology should be used together. Often times we find utilizing Ultrasound Guided injections helpful for pain localization especially when attempting to differentiate intra-articular process from a painful AC joint. 

Examination Findings Based on Injury Grade

Type I Injury.
In a type I injury, there is minimal to moderate tenderness to palpation over the AC joint. In the acute patient, mild swelling over the AC joint may be present. Usually there is only minimal pain with arm movements, including adduction across the body. Tenderness is not present in the CC interspace. These patients respond very well to local anesthetic/corticosteroid injections for reduction of inflammation and acute pain relief. By definition, this grade does not demonstrate significant displacement visualized or quantifiable on radiography. 
Type II Injury.
By definition this grade has a higher degree of injury to the AC ligaments and capsule and consequently typically presents with moderate to severe pain with palpation of the joint. If the patient is examined shortly after injury, the outer end of the clavicle may be noted to be slightly superior to the acromion, and ecchymosis may be present. Adduction motion of the shoulder typically produces pain in the AC joint, as well as lateral pressure. A common complaint is difficulty sleeping. If the distal clavicle is grasped and the acromion stabilized, anterior–posterior motion of the clavicle in the horizontal plane can be evaluated after the acute inflammation has decreased. There should be little, if any, instability in the vertical plane (Fig. 41-5). Tenderness may be noted when the physician palpates anteriorly in the CC interspace. Radiographic evidence is subtle and would demonstrate small (<50% clavicle width) of superior clavicle displacement at AC joint if compared to contralateral side on a bilateral Zanca AC joint view. 
Figure 41-5
Clinical photo of a patient with type III AC joint dislocation with symptomatic instability with cross-arm adduction.
 
Looking from lateral, examiner is grabbing the acromion with right hand and clavicle with the left, which is easily translated anterior and posterior approximately 3 to 5 cm.
Looking from lateral, examiner is grabbing the acromion with right hand and clavicle with the left, which is easily translated anterior and posterior approximately 3 to 5 cm.
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Figure 41-5
Clinical photo of a patient with type III AC joint dislocation with symptomatic instability with cross-arm adduction.
Looking from lateral, examiner is grabbing the acromion with right hand and clavicle with the left, which is easily translated anterior and posterior approximately 3 to 5 cm.
Looking from lateral, examiner is grabbing the acromion with right hand and clavicle with the left, which is easily translated anterior and posterior approximately 3 to 5 cm.
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Type III Injury.
The patient with a type III injury characteristically presents with the upper extremity held adducted close to the body and supported in an elevated position to relieve the pain in the AC joint. By definition the AC joint capsule and ligaments are disrupted and the CC ligaments have significant injury that allows inferior translation of the limb and produces the characteristic shoulder droop sign (Fig. 41-6). Consequently, the clavicle may be prominent enough to tent the skin. Moderate pain is the rule, and any motion of the arm, particularly abduction, increases the pain. 
Figure 41-6
Clinical photo of a patient with a chronic type III (based on Zanca views) localizing his pain with activity to the deformity.
Rockwood-ch041-image006.png
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Tenderness is noted at the AC joint, the CC interspace, and along the superior aspect of the lateral fourth of the clavicle. The entire length of the clavicular shaft should be palpated to detect an associated clavicle shaft fracture. The lateral clavicle is unstable in both the horizontal and vertical planes (Fig. 41-5). The key to the diagnosis of a type III injury is that the AC joint can be reduced with upward pressure under the elbow, or by having the patient actively shrug and reduce the joint; this is known as the “shrug test.” A type III or reducible injury is thus differentiated from a type IV or V injury, which cannot be reduced if the deltotrapezial fascia is interposed. 
Considerable controversy surrounds the gradation by radiography and thus it is important to utilize bilateral, or Zanca, views of the AC joints without weights. This allows for the measurements to be used for classification: (1) The amount of displacement of distal clavicle above the acromion, this has been measured in percentage of clavicle width or a direct measurement in millimeter from superior clavicle to superior acromion. (2) The distance from undersurface of clavicle to superior cortex of the coracoid process (Fig. 41-7). 
Figure 41-7
 
A: Radiographic quantification of AC joint displacement with Zanca radiograph with bilateral AC joints on one cassette for direct comparison, note the AC joint injury on the left side. B: Same Zanca radiograph with the two areas measured for quantifying the amount of displacement, CC (Coracoclavicular) distance and percentage displacement of distal clavicle above acromion.
A: Radiographic quantification of AC joint displacement with Zanca radiograph with bilateral AC joints on one cassette for direct comparison, note the AC joint injury on the left side. B: Same Zanca radiograph with the two areas measured for quantifying the amount of displacement, CC (Coracoclavicular) distance and percentage displacement of distal clavicle above acromion.
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Figure 41-7
A: Radiographic quantification of AC joint displacement with Zanca radiograph with bilateral AC joints on one cassette for direct comparison, note the AC joint injury on the left side. B: Same Zanca radiograph with the two areas measured for quantifying the amount of displacement, CC (Coracoclavicular) distance and percentage displacement of distal clavicle above acromion.
A: Radiographic quantification of AC joint displacement with Zanca radiograph with bilateral AC joints on one cassette for direct comparison, note the AC joint injury on the left side. B: Same Zanca radiograph with the two areas measured for quantifying the amount of displacement, CC (Coracoclavicular) distance and percentage displacement of distal clavicle above acromion.
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Type IV Injury.
The patient with a type IV injury has essentially all the clinical findings of a type III injury. In addition, examination of the seated patient from above reveals that the outline of the displaced clavicle is inclined posteriorly compared with the uninjured shoulder. The clavicle usually is displaced so severely posteriorly that it becomes “buttonholed” through the trapezius muscle and tents the posterior skin (Fig. 41-8). Consequently, motion of the shoulder is more painful than in a type III injury. Often times in this injury pattern, the AC joint cannot be reduced manually. There is no evidence to support operating room reduction, but injection with lidocaine and attempted reduction if Acute is reasonable. It is important to remember with this injury pattern to examine the SC joint for an associated anterior dislocation, termed “bipolar” or “floating clavicle” injuries AC and SC dislocation can occur together, as discussed in a previous section within this chapter. 
Figure 41-8
Patient with type IV AC joint injury.
 
Note that the distal end of the clavicle is displaced posteriorly back into and through the trapezius muscle. (From Rockwood CA, Young DC. Disorders of the acromioclavicular joint. In: Rockwood CA, Matsen F III, eds. The Shoulder. Philadelphia, PA: WB Saunders; 1990:446.)
Note that the distal end of the clavicle is displaced posteriorly back into and through the trapezius muscle. (From Rockwood CA, Young DC. Disorders of the acromioclavicular joint. In: Rockwood CA, Matsen F III, eds. The Shoulder. Philadelphia, PA: WB Saunders; 1990:446.)
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Figure 41-8
Patient with type IV AC joint injury.
Note that the distal end of the clavicle is displaced posteriorly back into and through the trapezius muscle. (From Rockwood CA, Young DC. Disorders of the acromioclavicular joint. In: Rockwood CA, Matsen F III, eds. The Shoulder. Philadelphia, PA: WB Saunders; 1990:446.)
Note that the distal end of the clavicle is displaced posteriorly back into and through the trapezius muscle. (From Rockwood CA, Young DC. Disorders of the acromioclavicular joint. In: Rockwood CA, Matsen F III, eds. The Shoulder. Philadelphia, PA: WB Saunders; 1990:446.)
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This type is best observed on the axillary radiograph. It will show the distal clavicle posterior to the glenoid and displaced posterior to the end of the acromion (Fig. 41-9). 
Figure 41-9
Axillary radiograph of a patient with a type IV AC joint injury.
 
Note the posterior displacement of the clavicle.
Note the posterior displacement of the clavicle.
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Figure 41-9
Axillary radiograph of a patient with a type IV AC joint injury.
Note the posterior displacement of the clavicle.
Note the posterior displacement of the clavicle.
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Type V Injury.
The type V injury is an exaggeration of the type III injury in which the distal end of the clavicle appears to be grossly superiorly displaced and tenting the skin (Fig. 41-10). This apparent deformity is the result of downward displacement of the upper extremity. The patient has more pain than with a type III injury, particularly over the distal half of the clavicle. This is secondary to the extensive muscle and soft tissue disruption around the clavicle that occurs with this injury. Often the shoulder musculature becomes weak secondary to disuse or as part of the injury pattern resulting in scapular dyskinesis. This can significantly impact the shoulder function and cause pain (Fig. 41-11).65 
Figure 41-10
 
Clinical images of a football player with type V (radiographic) separation, picture taken from facing front and posterior to demonstrate skin tenting secondary to displacement through the deltotrapezial fascia.
Clinical images of a football player with type V (radiographic) separation, picture taken from facing front and posterior to demonstrate skin tenting secondary to displacement through the deltotrapezial fascia.
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Figure 41-10
Clinical images of a football player with type V (radiographic) separation, picture taken from facing front and posterior to demonstrate skin tenting secondary to displacement through the deltotrapezial fascia.
Clinical images of a football player with type V (radiographic) separation, picture taken from facing front and posterior to demonstrate skin tenting secondary to displacement through the deltotrapezial fascia.
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Figure 41-11
Clinical picture of a patient with a chronic type III AC joint dislocation with significant scapula dyskinesia.
 
This is the same patient from Figure 41-6. Note the scapula position as the patient attempts to forward flex his arm.
This is the same patient from Figure 41-6. Note the scapula position as the patient attempts to forward flex his arm.
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Figure 41-11
Clinical picture of a patient with a chronic type III AC joint dislocation with significant scapula dyskinesia.
This is the same patient from Figure 41-6. Note the scapula position as the patient attempts to forward flex his arm.
This is the same patient from Figure 41-6. Note the scapula position as the patient attempts to forward flex his arm.
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The radiographic assessment using the comparative Zanca view is important as this type represents a high degree of injury than the type III and thus larger distances between the clavicle and coracoid (CC distance) as well as the distance in displacement between the distal clavicle and coracoid (Fig. 41-7). 
Type VI Injury.
Type VI injuries are very rare. The superior aspect of the shoulder has a flat appearance, as opposed to the rounded contour of the normal shoulder. With palpation, the acromion is prominent, and there is a definite step to the superior surface of the coracoid process. Because of the degree of trauma required to produce a subcoracoid dislocation of the clavicle, there may be associated fractures of the clavicle and upper ribs or injury to the upper roots of the brachial plexus. These associated injuries may produce so much swelling of the shoulder that the disruption of the AC joint may not be recognized initially.59,100,138 No vascular injuries were noted. However, all the adult cases reported by McPhee and Gerber and Rockwood had transient paresthesias before reduction of the dislocation. After reduction, the neurologic deficits did resolve. 

Imaging and Other Diagnostic Studies for Acromioclavicular Joint Injury

Good-quality radiographs of the AC joint require one-third to one-half the beam penetration required to image the glenohumeral joint. Radiographs of the AC joint taken using routine shoulder technique will be overpenetrated (i.e., dark), and small fractures may be overlooked. Therefore, the radiographic technician must be specifically requested to take radiographs of the “AC joint” rather than the “shoulder.” 

Anteroposterior Views

Routine AP views should be obtained with the patient standing or sitting and their back against the x-ray cassette, the arms hanging unsupported at the side. Because of significant individual variation in AC joint anatomy and because the CC interspace will vary with the angle of the x-ray beam and with the distance between the beam and the patient, both AC joints should be imaged simultaneously on one large (14- × 17-in) cassette. Large patients with shoulders too broad to be visualized on a single cassette should have radiographs made with two smaller (10- × 12-in) cassettes using identical technique. 
The difficulty in evaluating AC joint injuries lies in the fact that with this projection, the distal clavicle and acromion are superimposed on the spine of the scapula. Subtle fractures of the distal clavicle are easily missed. Zanca168 noted this during a review of 1,000 radiographs of patients with shoulder pain. Therefore, he recommended a 10- to 15-degree cephalic tilt view to project an unobscured image of the joint (Fig. 41-12). This cephalic tip not only allows for better exposure but also standardizes the distance between clavicle and coracoid which apparently increases with a more AP view secondary to x-ray parallax and bone contour (Fig. 41-12). This view is now routinely used in the evaluation of AC joint injuries and is particularly useful when there is suspicion of a small fracture or loose body on routine views (Fig. 41-7A,B). 
Figure 41-12
 
A: Illustration of the “Zanca view” which is shot with the x-ray beam placed 10 degrees cephalad to the perpendicular plane. B: Radiograph of shoulder perpendicular to floor. C: Radiograph done with Zanca view—10-degree cephalad tilt to demonstrate the effect of the view on the AC joint alignment and visualization of the CC distance.
A: Illustration of the “Zanca view” which is shot with the x-ray beam placed 10 degrees cephalad to the perpendicular plane. B: Radiograph of shoulder perpendicular to floor. C: Radiograph done with Zanca view—10-degree cephalad tilt to demonstrate the effect of the view on the AC joint alignment and visualization of the CC distance.
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Figure 41-12
A: Illustration of the “Zanca view” which is shot with the x-ray beam placed 10 degrees cephalad to the perpendicular plane. B: Radiograph of shoulder perpendicular to floor. C: Radiograph done with Zanca view—10-degree cephalad tilt to demonstrate the effect of the view on the AC joint alignment and visualization of the CC distance.
A: Illustration of the “Zanca view” which is shot with the x-ray beam placed 10 degrees cephalad to the perpendicular plane. B: Radiograph of shoulder perpendicular to floor. C: Radiograph done with Zanca view—10-degree cephalad tilt to demonstrate the effect of the view on the AC joint alignment and visualization of the CC distance.
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Axillary Lateral View

As with any musculoskeletal injury, a radiograph in one plane is not sufficient to classify an AC joint injury. An axillary lateral view should be taken of the injured shoulder when an AC dislocation is suspected. The cassette should be placed on the superior aspect of the shoulder and medial enough to expose as much of the lateral third of the clavicle as possible. This will reveal any posterior displacement of the clavicle as well as any small fractures that may have been missed on the AP view within the coracoid (Fig. 41-9). 

Stryker Notch View

A variant of an AC joint injury involves a fracture of the coracoid process. This injury should be suspected when there is an AC joint dislocation on the AP projection, but the CC distance is normal, or equal to that on the opposite, uninvolved side. A Stryker notch view taken appropriately puts the coracoid in profile and is the best view for evaluating this injury. This is performed with the patient supine and the arm elevated over the head with the palm behind the head. The humerus must be parallel to the longitudinal axis of the body, with the elbow pointed straight toward the ceiling (Fig. 41-13). This can be a difficult view to obtain in the acutely injured shoulder.10 
Figure 41-13
 
A: Illustration of positioning for the Stryker notch view. B: Stryker notch view radiograph of a patient. Note the view of the coracoid base where a fracture could be visualized.
A: Illustration of positioning for the Stryker notch view. B: Stryker notch view radiograph of a patient. Note the view of the coracoid base where a fracture could be visualized.
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Figure 41-13
A: Illustration of positioning for the Stryker notch view. B: Stryker notch view radiograph of a patient. Note the view of the coracoid base where a fracture could be visualized.
A: Illustration of positioning for the Stryker notch view. B: Stryker notch view radiograph of a patient. Note the view of the coracoid base where a fracture could be visualized.
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Other Modalities

Schmid and Schmid137 reported the use of ultrasonography in the diagnosis of 22 cases of type III AC dislocation. Ultrasound examination demonstrated visible instability of the distal clavicle, incongruity of the joint, hematoma formation, and visible ligament remnants in all cases. In the case of a painful type II or type III chronic injury the ultrasound study can delineate dynamic instability specifically in the anterior–posterior direction. This does help in surgical decision-making process, as unstable patients with chronic disruptions may be candidates for surgical repair. In the typical patient, sophisticated imaging modalities as ultrasonography, computed tomography (CT), and magnetic resonance imaging are not required. Plain radiography continues to be the most readily available, cost-effective method for routine investigation of injuries to the AC joint (Table 41-1). 
 
Table 41-1
Summary of Clinical Presentation and Diagnostic Work up
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Table 41-1
Summary of Clinical Presentation and Diagnostic Work up
Mechanism of Injury
Direct Trauma
  •  
    Force to lateral shoulder/acromion with adducted arm
  •  
    Medial and inferior force resulting in progression of injury
    •  
      AC joint ligaments
    •  
      CC ligaments
    •  
      Deltotrapezial fascia
  •  
    Landing on outstretched arm or flexed elbow forcing humeral head into acromion
    •  
      Usually results in AC joint/ligament injury
    •  
      Can result in instability at AC joint (anterior–posterior direction) without CC ligament complex injury (minimal dislocation)

Nontraumatic or Chronic Overuse
  •  
    AC joint arthrosis—weight lifting, laborer (pneumatic jackhammer), repetitive overhead activity
  •  
    Repetitive low-grade AC joint injuries
  •  
    Medical cause: Rheumatoid arthritis, hyperparathyroidism, scleroderma, and rarely Gorham’s osteolysis

Physical Examination
Diffuse Shoulder Pain—anterolateral neck, AC joint, anterolateral deltoid
Point tender at AC joint ± deformity (prominence)
  •  
    Positive cross-arm adduction test (arm flexed 90 degrees, adducted across chest) produces compression pain localized to AC joint
  •  
    O’Brien’s active compression test with localized pain over AC joint
  •  
    Paxinos test (thumb pressure directed anterior at the posterior AC joint)
  •  
    Diagnostic analgesic injection—positive relief in pain/symptoms

Radiographic Findings
  •  
    Zanca view to determine displacement with comparison to contralateral AC joint and CC distance
  •  
    Zanca view: Beam placed 10–15 degrees cephalad and using 50% of the AP penetration strength
  •  
    Axillary view—determine anterior/posterior position of distal clavicle in relation to acromion
  •  
    Cross-arm stress view—Basmania view (AP with arm adducted)
  •  
    Reducibility Stress Views—Active shrug maneuver with AP of shoulder or with patient applying upload directed load on elbow by lining on table while radigraph of AC joint (Goal: determine is deltotrapezial fascia interposed to prevent reduction)
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Classification of Acromioclavicular Joint Injury

AC joint injuries are best classified according to the extent of damage inflicted by a given force. However, unlike other joints, the differential diagnosis of sprains of the AC joint is based on the severity of injury sustained by the capsular ligaments (AC ligaments) and extracapsular ligaments (CC ligaments), as well as the supporting musculature (deltoid and trapezius muscles). Therefore, injuries to the AC joint are graded according to the amount of injury to the AC and CC ligaments. Injuries in this anatomic area have traditionally been referred to as “AC joint injuries,” although they have varying degrees of disruption between the scapula and the clavicle, not limited to the one particular joint. 
The strength of any classification system depends on its ability to guide treatment and predict prognosis. Rockwood et al.127,163 developed the most widely accepted classification system, based on the original work of Tossy et al.154 in 1963. It is an expanded, accurate classification system based on the anatomic severity of the injury. The modified classification is described below, summarized in Table 41-2, and illustrated in Figure 41-14
Figure 41-14
Schematic drawings of the classification of ligamentous injuries to the AC joint.
 
A: In the type I injury, a mild force applied to the point of the shoulder does not disrupt either the AC or the coracoclavicular ligaments. B: A moderate to heavy force applied to the point of the shoulder will disrupt the AC ligaments, but the coracoclavicular ligaments remain intact (type II). C: When a severe force is applied to the point of the shoulder both the AC and the coracoclavicular ligaments are disrupted (type III). D: In a type IV injury, not only are the ligaments disrupted, but the distal end of the clavicle is also displaced posteriorly into or through the trapezius muscle. E: A larger enough force applied to the point of the shoulder not only ruptures the AC and coracoclavicular ligaments but also disrupts the muscle attachments and creates a major separation between the clavicle and the acromion (type V). F: This is an inferior dislocation of the distal clavicle in which the clavicle is inferior to the coracoid process and posterior to the biceps and coracobrachialis tendons. The AC and coracoclavicular ligaments are also disrupted (type VI).
A: In the type I injury, a mild force applied to the point of the shoulder does not disrupt either the AC or the coracoclavicular ligaments. B: A moderate to heavy force applied to the point of the shoulder will disrupt the AC ligaments, but the coracoclavicular ligaments remain intact (type II). C: When a severe force is applied to the point of the shoulder both the AC and the coracoclavicular ligaments are disrupted (type III). D: In a type IV injury, not only are the ligaments disrupted, but the distal end of the clavicle is also displaced posteriorly into or through the trapezius muscle. E: A larger enough force applied to the point of the shoulder not only ruptures the AC and coracoclavicular ligaments but also disrupts the muscle attachments and creates a major separation between the clavicle and the acromion (type V). F: This is an inferior dislocation of the distal clavicle in which the clavicle is inferior to the coracoid process and posterior to the biceps and coracobrachialis tendons. The AC and coracoclavicular ligaments are also disrupted (type VI).
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Figure 41-14
Schematic drawings of the classification of ligamentous injuries to the AC joint.
A: In the type I injury, a mild force applied to the point of the shoulder does not disrupt either the AC or the coracoclavicular ligaments. B: A moderate to heavy force applied to the point of the shoulder will disrupt the AC ligaments, but the coracoclavicular ligaments remain intact (type II). C: When a severe force is applied to the point of the shoulder both the AC and the coracoclavicular ligaments are disrupted (type III). D: In a type IV injury, not only are the ligaments disrupted, but the distal end of the clavicle is also displaced posteriorly into or through the trapezius muscle. E: A larger enough force applied to the point of the shoulder not only ruptures the AC and coracoclavicular ligaments but also disrupts the muscle attachments and creates a major separation between the clavicle and the acromion (type V). F: This is an inferior dislocation of the distal clavicle in which the clavicle is inferior to the coracoid process and posterior to the biceps and coracobrachialis tendons. The AC and coracoclavicular ligaments are also disrupted (type VI).
A: In the type I injury, a mild force applied to the point of the shoulder does not disrupt either the AC or the coracoclavicular ligaments. B: A moderate to heavy force applied to the point of the shoulder will disrupt the AC ligaments, but the coracoclavicular ligaments remain intact (type II). C: When a severe force is applied to the point of the shoulder both the AC and the coracoclavicular ligaments are disrupted (type III). D: In a type IV injury, not only are the ligaments disrupted, but the distal end of the clavicle is also displaced posteriorly into or through the trapezius muscle. E: A larger enough force applied to the point of the shoulder not only ruptures the AC and coracoclavicular ligaments but also disrupts the muscle attachments and creates a major separation between the clavicle and the acromion (type V). F: This is an inferior dislocation of the distal clavicle in which the clavicle is inferior to the coracoid process and posterior to the biceps and coracobrachialis tendons. The AC and coracoclavicular ligaments are also disrupted (type VI).
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Table 41-2
Summary Table of Tossy–Rockwood AC Joint Dislocation Classification
Type I A mild force to the point of the shoulder produces a minor strain to the fibers of the AC ligaments. The ligaments remain intact, and the AC joint remains stable.
Type II A moderate force to the point of the shoulder is severe enough to rupture the ligaments of the AC joint. The distal end of the clavicle is unstable in the horizontal plane (i.e., anteroposterior), but vertical (i.e., superoinferior) stability is preserved by virtue of the (damaged but) intact coracoclavicular ligament. The scapula may rotate medially, producing a widening of the AC joint. There may be a slight, relative upward displacement of the distal end of the clavicle secondary to stretching of the coracoclavicular ligaments.
Type III A severe force is applied to the point of the shoulder which tears the AC and coracoclavicular ligaments resulting in a complete AC dislocation. The distal clavicle appears to be displaced superiorly as the scapula and shoulder complex droop inferomedially. Radiographic findings include a 25–100% increase in the coracoclavicular space in comparison to the normal shoulder.126
Type IV Posterior dislocation of the distal end of the clavicle, or a type IV AC dislocation, is relatively rare. The clavicle is posteriorly displaced into or through the trapezius muscle as the force applied to the acromion drives the scapula anteriorly and inferiorly. Posterior clavicular displacement may be so severe that the skin on the posterior aspect of the shoulder becomes tented. The literature concerning posterior AC dislocations consists mostly of small series and case reports.69,93 Some5,11,145 refer to this injury as a “posterior dislocation of the clavicle,” and others69,111 prefer the term “anterior dislocation of the AC joint.”
Type V Type V AC dislocation is a markedly more severe version of the type III injury. The distal clavicle has been stripped of all its soft tissue attachments (i.e., AC ligaments, coracoclavicular ligament, and the deltotrapezial muscle attachments) and lies subcutaneously. When combined with superior displacement of the clavicle owing to unopposed pull of the sternocleidomastoid muscle, the severe downward droop of the extremity produces a marked disfiguration of the shoulder. Radiographically, the coracoclavicular space is increased greater than 100% in comparison to the opposite, normal shoulder.126
Type VI Inferior dislocation of the distal clavicle, or type VI AC dislocation, is an exceedingly rare injury.59,100,129 Gerber and Rockwood’s59 series of three patients is the largest one reported in the literature. The injury is often the result of severe trauma and is frequently accompanied by multiple injuries. The mechanism of dislocation is thought to be severe hyperabduction and external rotation of the arm, combined with retraction of the scapula. The distal clavicle occupies either a subacromial or a subcoracoid location.
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In all reported cases of subcoracoid dislocation, the clavicle has become lodged behind an intact conjoined tendon. The AC ligaments are disrupted in either a subacromial or subcoracoid dislocation. The CC ligament, however, is intact in a subacromial dislocation and completely disrupted in a subcoracoid dislocation. Likewise, the integrity of the deltoid and trapezius muscle attachments depends on the degree of clavicular displacement. 

Normal Joints

The width and configuration of the AC joint in the coronal plane may vary significantly from individual to individual. This should be remembered so that a normal variant is not mistaken as an injury. In a study of 100 radiographs of normal shoulders, Urist157 found that nearly half (49%) of the AC joints were inclined superolateral to inferomedial, with the articular surface of the clavicle overriding the acromion; 27% were vertical and 3% were inclined superomedial to inferolateral, with the articular surface of the clavicle underriding the acromion. Another 21% of the joints were incongruent, with the clavicle lying either superior or inferior to the acromial articular surface. 
The normal width of the AC joint in the coronal plane is 1 to 3 mm. Petersson and Redlund-Johnell119 measured AC joint width radiographically in 151 normal individuals and drew several conclusions: The AC joint space normally diminishes with increasing age, a joint space of 0.5 mm in a patient older than 60 years is conceivably normal, and a joint space of greater than 7 mm in men and 6 mm in women is pathologic. 
The CC interspace also exhibits significant individual variation. The average distance between the clavicle and the coracoid process ranges from 1.1 to 1.3 cm.7 An increase in the CC distance of 50% over the normal side signifies a complete AC dislocation.7 Complete dislocation has been seen with as little as a 25% increase in the CC distance. 
Type I Injury.
In a type I injury, the radiographs of the AC joint are normal, except for mild soft tissue swelling, as compared with the uninjured shoulder. There is no radiographic widening, no separation, and no deformity. 
Type II Injury.
In a type II injury, the lateral end of the clavicle may be slightly elevated. The AC joint, when compared with the normal side, may appear to be widened. The widening probably results from a slight medial rotation of the scapula and slight posterior displacement of the clavicle due to trapezius muscle contraction. The CC space of the injured shoulder is the same as that of the normal shoulder. 
Type III Injury.
In type III AC dislocations, the joint is totally displaced. The lateral end of the clavicle is displaced completely above the superior border of the acromion and the CC interspace is significantly (25% to 100%) greater than in the normal shoulder (Fig. 41-15). Fractures may be noted involving the distal clavicle or the acromion process. 
Figure 41-15
X-ray appearance of a grade III injury.
 
Not only is the right AC joint displaced compared with the left, but also, more significantly, notice the great increase in the coracoclavicular interspace on the injured right shoulder compared with the normal left shoulder.
Not only is the right AC joint displaced compared with the left, but also, more significantly, notice the great increase in the coracoclavicular interspace on the injured right shoulder compared with the normal left shoulder.
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Figure 41-15
X-ray appearance of a grade III injury.
Not only is the right AC joint displaced compared with the left, but also, more significantly, notice the great increase in the coracoclavicular interspace on the injured right shoulder compared with the normal left shoulder.
Not only is the right AC joint displaced compared with the left, but also, more significantly, notice the great increase in the coracoclavicular interspace on the injured right shoulder compared with the normal left shoulder.
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Rarely, complete AC dislocation will be accompanied by a fracture of the coracoid process rather than by disruption of the CC ligaments. Although the fracture of the coracoid process is difficult to visualize on routine radiographs, its presence should be suspected because of the presence of a complete AC separation and a normal CC distance, as compared with the uninjured shoulder. The ideal radiograph for visualizing the coracoid fracture is the Stryker notch view (as described) (Fig. 41-16). A few unusual injury patterns uncommonly occur and are variations of type III dislocations. Most often, complete separation of the articular surfaces of the distal clavicle and acromion is accompanied by complete disruption of the AC and CC ligaments. 
Figure 41-16
Radiographs of a patient with a type III variant injury involving the AC joint and a fracture of both the base and the tip of the coracoid.
 
A: An anteroposterior radiograph of the injured right side. The coracoid injury is not visualized. B: A radiograph of the uninjured left side demonstrating that the coracoclavicular distance is equal on the injured and unaffected sides. C: An axillary view shows the tip fracture, but the fracture at the base is not easily detected. D: The West Point view clearly shows the fracture at the tip of the coracoid process. E: The Stryker notch view clearly shows the fracture at the base of the coracoid. F: Nonoperative treatment in this case led to an excellent result as evidenced by full overhead elevation. G: The patient regained near-normal internal rotation.
A: An anteroposterior radiograph of the injured right side. The coracoid injury is not visualized. B: A radiograph of the uninjured left side demonstrating that the coracoclavicular distance is equal on the injured and unaffected sides. C: An axillary view shows the tip fracture, but the fracture at the base is not easily detected. D: The West Point view clearly shows the fracture at the tip of the coracoid process. E: The Stryker notch view clearly shows the fracture at the base of the coracoid. F: Nonoperative treatment in this case led to an excellent result as evidenced by full overhead elevation. G: The patient regained near-normal internal rotation.
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A: An anteroposterior radiograph of the injured right side. The coracoid injury is not visualized. B: A radiograph of the uninjured left side demonstrating that the coracoclavicular distance is equal on the injured and unaffected sides. C: An axillary view shows the tip fracture, but the fracture at the base is not easily detected. D: The West Point view clearly shows the fracture at the tip of the coracoid process. E: The Stryker notch view clearly shows the fracture at the base of the coracoid. F: Nonoperative treatment in this case led to an excellent result as evidenced by full overhead elevation. G: The patient regained near-normal internal rotation.
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Figure 41-16
Radiographs of a patient with a type III variant injury involving the AC joint and a fracture of both the base and the tip of the coracoid.
A: An anteroposterior radiograph of the injured right side. The coracoid injury is not visualized. B: A radiograph of the uninjured left side demonstrating that the coracoclavicular distance is equal on the injured and unaffected sides. C: An axillary view shows the tip fracture, but the fracture at the base is not easily detected. D: The West Point view clearly shows the fracture at the tip of the coracoid process. E: The Stryker notch view clearly shows the fracture at the base of the coracoid. F: Nonoperative treatment in this case led to an excellent result as evidenced by full overhead elevation. G: The patient regained near-normal internal rotation.
A: An anteroposterior radiograph of the injured right side. The coracoid injury is not visualized. B: A radiograph of the uninjured left side demonstrating that the coracoclavicular distance is equal on the injured and unaffected sides. C: An axillary view shows the tip fracture, but the fracture at the base is not easily detected. D: The West Point view clearly shows the fracture at the tip of the coracoid process. E: The Stryker notch view clearly shows the fracture at the base of the coracoid. F: Nonoperative treatment in this case led to an excellent result as evidenced by full overhead elevation. G: The patient regained near-normal internal rotation.
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A: An anteroposterior radiograph of the injured right side. The coracoid injury is not visualized. B: A radiograph of the uninjured left side demonstrating that the coracoclavicular distance is equal on the injured and unaffected sides. C: An axillary view shows the tip fracture, but the fracture at the base is not easily detected. D: The West Point view clearly shows the fracture at the tip of the coracoid process. E: The Stryker notch view clearly shows the fracture at the base of the coracoid. F: Nonoperative treatment in this case led to an excellent result as evidenced by full overhead elevation. G: The patient regained near-normal internal rotation.
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Children and adolescents may sustain a variant of complete AC dislocation. Radiographs reveal displacement of the distal clavicular metaphysis superiorly with a large increase in the CC interspace. These injuries are most often Salter–Harris type I or II injuries in which the epiphysis and the intact AC joint remain in their anatomic locations whereas the distal clavicular metaphysis is displaced superiorly through a dorsal rent in the periosteal sleeve (Fig. 41-17).12,37,47,48,71 The lateral epiphysis of the clavicle is barely visible because it is thin and fuses over a short time period at approximately 19 years of age. Eidman et al.47 reported on 25 AC injuries in children treated surgically. In all patients younger than 13 years of age, there was a lateral Salter–Harris clavicular fracture rather than a true AC dislocation. The importance of recognizing this injury is that the intact CC ligaments remain attached to the periosteal sleeve. Nonoperative management most often results in healing of the clavicular fracture and thus re-establishment of the integrity of the CC ligaments. Those authors who recommend surgical repair in selected instances emphasize the importance of repairing the dorsal rent in the periosteal sleeve.47,48 
Figure 41-17
 
A: In children and adolescents, the distal clavicular physis lies medial to the AC capsular reflection. Injuries in this age group are often type II Salter–Harris fractures involving the physis rather than AC dislocations. B. The coracoclavicular ligaments remain attached to the intact periosteal sleeve whereas the medial clavicular fragment displaces through a dorsal periosteal rent.
A: In children and adolescents, the distal clavicular physis lies medial to the AC capsular reflection. Injuries in this age group are often type II Salter–Harris fractures involving the physis rather than AC dislocations. B. The coracoclavicular ligaments remain attached to the intact periosteal sleeve whereas the medial clavicular fragment displaces through a dorsal periosteal rent.
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Figure 41-17
A: In children and adolescents, the distal clavicular physis lies medial to the AC capsular reflection. Injuries in this age group are often type II Salter–Harris fractures involving the physis rather than AC dislocations. B. The coracoclavicular ligaments remain attached to the intact periosteal sleeve whereas the medial clavicular fragment displaces through a dorsal periosteal rent.
A: In children and adolescents, the distal clavicular physis lies medial to the AC capsular reflection. Injuries in this age group are often type II Salter–Harris fractures involving the physis rather than AC dislocations. B. The coracoclavicular ligaments remain attached to the intact periosteal sleeve whereas the medial clavicular fragment displaces through a dorsal periosteal rent.
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A variation of the type III injury involves complete separation of the AC articular surface combined with a fracture of the coracoid process.25,81,95 This is an extremely uncommon injury. In most cases the CC ligaments have remained intact and attached to the displaced coracoid process fracture, which most often occurs through the base. 
Both operative and nonoperative methods of treatment have been described for combined AC dislocation and coracoid process fracture with intact CC ligaments. Results seem to be similar in both groups. Therefore, most authors recommend nonoperative treatment. Most often, the coracoid process fracture is extra-articular. However, we have encountered instances in which the coracoid fragment contains a significant portion of the glenoid fossa. The conjoined tendon rotates the coracoid process and glenoid inferolaterally and can result in substantial articular displacement. In this situation, open reduction and internal fixation may be necessary and is predicated on the amount of displacement of the articular fragment (Fig. 41-18).128 
Figure 41-18
Coracoid fracture with intra-articular extension.
 
A: Anteroposterior radiograph showing the fracture through the coracoid. B: A CT scan showing the glenoid displacement necessitating open reduction and internal fixation of the glenoid.
A: Anteroposterior radiograph showing the fracture through the coracoid. B: A CT scan showing the glenoid displacement necessitating open reduction and internal fixation of the glenoid.
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Figure 41-18
Coracoid fracture with intra-articular extension.
A: Anteroposterior radiograph showing the fracture through the coracoid. B: A CT scan showing the glenoid displacement necessitating open reduction and internal fixation of the glenoid.
A: Anteroposterior radiograph showing the fracture through the coracoid. B: A CT scan showing the glenoid displacement necessitating open reduction and internal fixation of the glenoid.
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Type IV Injury.
Although the radiographic findings associated with a type IV injury include a relative upward displacement of the clavicle from the acromion and an increase in the CC interspace, the most striking feature is the posterior displacement of the distal clavicle, as seen on the axillary lateral radiograph (Fig. 41-19). In patients with heavy, thick shoulders or in patients with multiple injuries in whom an axillary lateral view of the shoulder or a scapular lateral radiographic view cannot be taken, a CT scan may be of great value in helping to confirm clinical suspicions of a posteriorly dislocated AC joint. 
Figure 41-19
Type IV posterior dislocation of the AC joint.
 
A: Axillary lateral radiograph of the right shoulder. B: Axillary view with the distal clavicle and acromion outlined.
A: Axillary lateral radiograph of the right shoulder. B: Axillary view with the distal clavicle and acromion outlined.
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Figure 41-19
Type IV posterior dislocation of the AC joint.
A: Axillary lateral radiograph of the right shoulder. B: Axillary view with the distal clavicle and acromion outlined.
A: Axillary lateral radiograph of the right shoulder. B: Axillary view with the distal clavicle and acromion outlined.
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Type V Injury.
The characteristic radiographic feature of type V injuries is a marked increase (100% to 300%) in the CC distance. The clavicle appears to be grossly displaced superiorly away from the acromion (Fig. 41-20). However, radiographs reveal that the clavicle on the injured side is actually at approximately the same level as the clavicle on the normal side, and the scapula is displaced inferiorly. 
Figure 41-20
The clavicle appears to be grossly displaced away from the acromion.
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Figure 41-20
An anteroposterior radiograph of a type V dislocation shows the marked increase in the coracoclavicular interspace.
The clavicle appears to be grossly displaced away from the acromion.
The clavicle appears to be grossly displaced away from the acromion.
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Type VI Injury.
There are two types of inferior AC dislocation: Subacromial and subcoracoid. In the subacromial type, radiographs reveal a decreased CC distance (i.e., less than the normal side), and the distal clavicle is in a subacromial location. The subcoracoid dislocation is characterized by a reversed CC distance, with the clavicle displaced inferior to the coracoid process (Fig. 41-21). Because this injury usually is the result of severe trauma, it often is accompanied by multiple other fractures of the clavicle and ribs. 
Figure 41-21
Type VI AC dislocation.
 
The distal end of the Left clavicle is in the subcoracoid position. The high-energy trauma causing this injury is evidenced by the bilateral chest tubes in this patient. (From Rockwood CA, Young DC. Disorders of the acromioclavicular joint. In: Rockwood CA, Matsen F III, eds. The Shoulder. Philadelphia, PA: WB Saunders; 1990:447. Courtesy of RC. Erickson and D. Massillion.)
The distal end of the Left clavicle is in the subcoracoid position. The high-energy trauma causing this injury is evidenced by the bilateral chest tubes in this patient. (From Rockwood CA, Young DC. Disorders of the acromioclavicular joint. In: Rockwood CA, Matsen F III, eds. The Shoulder. Philadelphia, PA: WB Saunders; 1990:447. Courtesy of RC. Erickson and D. Massillion.)
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Figure 41-21
Type VI AC dislocation.
The distal end of the Left clavicle is in the subcoracoid position. The high-energy trauma causing this injury is evidenced by the bilateral chest tubes in this patient. (From Rockwood CA, Young DC. Disorders of the acromioclavicular joint. In: Rockwood CA, Matsen F III, eds. The Shoulder. Philadelphia, PA: WB Saunders; 1990:447. Courtesy of RC. Erickson and D. Massillion.)
The distal end of the Left clavicle is in the subcoracoid position. The high-energy trauma causing this injury is evidenced by the bilateral chest tubes in this patient. (From Rockwood CA, Young DC. Disorders of the acromioclavicular joint. In: Rockwood CA, Matsen F III, eds. The Shoulder. Philadelphia, PA: WB Saunders; 1990:447. Courtesy of RC. Erickson and D. Massillion.)
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Outcome Measures for Acromioclavicular Joint Injury

The treatment of AC joint injures is an area of much controversy. The definition of injury pattern is based on the amount of separation or displacement observed on radiographs and classified by Rockwood.126 Traditional treatment of all injury patterns involves an early period of rest, ice, and immobilization with a sling. However, the time needed to return to sport is not clear. Recent reports suggest 10 to 15 days for low-grade, type I and II, injures is all that is needed; however, return to pain-free play or the need for anesthetic injections to play was not evaluated in these reports.2,4 However, clinical experience suggests the time to return to true pain-free sport with or without supplemental anesthetic injection may be longer. Among Australian Rules football and rugby players the use of local anesthetic injections for painful AC joint dislocations has been very successful with very limited side effects.9 In this population, the mean number of games using an injection to play was stratified among the various injuries treated: AC joint dislocations had the highest need, an average of 5.7 games.9 Clinical practice demonstrates that these competitive athletes will return to play despite a painful joint, but if given the option of local treatment to help symptoms will readily accept it. 

Pathoanatomy and Applied Anatomy Relating to Acromioclavicular Joint Injuries

Applied Anatomy of the Acromioclavicular Joint

The AC joint, a diarthrodial joint, is located between the medial margin of the acromion and lateral end of the clavicle. Within the AC joint, there is a fibrocartilaginous disk of varying size and shape. In viewing the AC joint from the anterior–posterior direction, the inclination of the joint may be almost vertical, or it may be inclined downward and medially, with the clavicle overriding the acromion by an angle as much as 50 degrees (Fig. 41-22).131 There may be an underriding type of inclination, with the clavicular facet under the acromion process. Approximately 50% of the time, the articular surface of the clavicle overrides the articular surface of the acromion resulting in incongruent articular surfaces. However, there is evidence to support that the articulating surfaces to impart some level biomechanical support and should be considered when surgical repair or reconstruction is performed.19 
Figure 41-22
Variations of the inclination of the AC and the sternoclavicular joints.
 
(Redrawn from DePalma AF. Surgery of the Shoulder. Philadelphia, PA: JB Lippincott; 1973.)
(Redrawn from DePalma AF. Surgery of the Shoulder. Philadelphia, PA: JB Lippincott; 1973.)
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Figure 41-22
Variations of the inclination of the AC and the sternoclavicular joints.
(Redrawn from DePalma AF. Surgery of the Shoulder. Philadelphia, PA: JB Lippincott; 1973.)
(Redrawn from DePalma AF. Surgery of the Shoulder. Philadelphia, PA: JB Lippincott; 1973.)
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There are two types of fibrocartilaginous intra-articular disks—complete and partial (meniscoid). The disk varies greatly in size and shape,41 and with age the meniscus undergoes degeneration until it is essentially no longer functional beyond the fourth decade.41,118,130 The nerve supply to the AC joint is from branches of the axillary, suprascapular, and lateral pectoral nerves (Fig. 41-4). 

Acromioclavicular Ligaments

The AC ligaments, consisting of anterior, posterior, superior, and inferior ligaments, surround the AC joint (Fig. 41-23). The fibers of the superior AC ligament, which are the strongest of the capsular ligaments, blend with the fibers of the deltoid and trapezius muscles, which are attached to the superior aspect of the clavicle and the acromion process. These muscle attachments are important in adding stability to the AC joint. The AC ligaments stabilize the joint in an AP direction (the horizontal plane).40,130,157 Recent studies have shown that the distance from the lateral clavicle to the insertion of the superior AC ligament/capsule ranges from 5.2 to 7 mm in women and approximately 8 mm in men.14,138 An AC resection that extends medial to the capsular insertion leads to instability in the horizontal plane.13 
Rockwood-ch041-image023.png
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Figure 41-23
Normal anatomy of the AC joint.
Rockwood-ch041-image023.png
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Coracoclavicular Ligament

The CC ligament is a very strong, heavy ligament whose fibers run from the outer, inferior surface of the clavicle to the base of the coracoid process of the scapula. The CC ligament has two components: The conoid and the trapezoid ligaments (Fig. 41-23). The trapezoid ligament measures from 0.8 to 2.5 cm in length and from 0.8 to 2.5 cm in width. The conoid ligament varies from 0.7 to 2.5 cm in length and from 0.4 to 0.95 cm in width.130 The distance from the lateral clavicle to the most lateral fibers of the trapezoid ligament may measure as little as 10 mm.14,67,68,124 
The conoid ligament, the more medial of the two ligaments, is cone shaped, with the apex of the cone attaching on the posteromedial side of the base of the coracoid process. The base of the cone attaches onto the conoid tubercle on the posterior undersurface of the clavicle. The conoid tubercle is located at the apex of the posterior clavicular curve, which is at the junction of the lateral third of the flattened clavicle with the medial two-thirds of the triangular shaft. 
The trapezoid ligament arises from the coracoid process, anterior and lateral to the attachment of the conoid ligament. This is just posterior to the attachment of the pectoralis minor tendon. The trapezoid ligament extends superiorly to a rough line on the undersurface of the clavicle. 

Biomechanics of the Acromioclavicular Joint

The biomechanics of the AC joint involve static stability, dynamic stability, and AC joint motion. The only connection between the upper extremity and the axial skeleton is through the clavicular articulations at the AC and SC joints. Moreover, through anatomic dissections of the SC ligaments, he demonstrated how these ligaments prevent downward displacement of the distal end of the clavicle. Hence, in the erect position, the strong SC ligaments support the clavicles suspended away from the body, like the wings from the body of an airplane. Furthermore, just as the jet engines are suspended from the underside of the wings, the upper extremities are suspended from the distal clavicles through the CC ligament. Thus, the CC ligament is the prime suspensory ligament of the upper extremity. 
AC joint stability is maintained predominantly by the surrounding ligamentous structures, specifically the CC ligaments (conoid and trapezoid) and the AC capsule and ligaments. Following excision of the AC joint capsule, Urist157 demonstrated that the distal clavicle could be completely dislocated anteriorly and posteriorly away from the acromion process. However, vertical displacement of the clavicle, in relation to the acromion, occurs only after the CC ligaments are transected (Fig. 41-24). Fukuda et al.52 performed load-displacement tests with a fixed displacement after sequential ligament sectioning to determine individual contributions of the various ligaments to AC stability. The contribution of the AC, trapezoid, and conoid ligaments was determined at small and large displacements. At small displacements, the AC ligaments were the primary restraint to both posterior (89%) and superior (68%) translation of the clavicle—the most common failure patterns seen clinically. At large displacements, the conoid ligament provided the primary restraint (62%) to superior translation, whereas the AC ligaments remained the primary restraint (90%) to posterior translation. At both large and small displacements, the trapezoid ligament served as the primary restraint to AC joint compression. 
Figure 41-24
The importance of the AC and coracoclavicular ligaments for stability of the AC joint, demonstrated in a fresh cadaver.
 
A: With the muscles and AC capsule and ligaments resected and with the coracoclavicular ligaments intact, the clavicle can be displaced anteriorly, as shown, or posteriorly from the articular surface of the acromion. B: However, because the coracoclavicular ligaments are intact, the clavicle cannot be displaced significantly upward. C: Following the transection of the coracoclavicular ligaments, the clavicle can be displaced completely above the acromion process. This suggests that the horizontal stability of the AC joint is accomplished by the AC ligaments, and vertical stability is obtained through the coracoclavicular ligaments.
A: With the muscles and AC capsule and ligaments resected and with the coracoclavicular ligaments intact, the clavicle can be displaced anteriorly, as shown, or posteriorly from the articular surface of the acromion. B: However, because the coracoclavicular ligaments are intact, the clavicle cannot be displaced significantly upward. C: Following the transection of the coracoclavicular ligaments, the clavicle can be displaced completely above the acromion process. This suggests that the horizontal stability of the AC joint is accomplished by the AC ligaments, and vertical stability is obtained through the coracoclavicular ligaments.
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Figure 41-24
The importance of the AC and coracoclavicular ligaments for stability of the AC joint, demonstrated in a fresh cadaver.
A: With the muscles and AC capsule and ligaments resected and with the coracoclavicular ligaments intact, the clavicle can be displaced anteriorly, as shown, or posteriorly from the articular surface of the acromion. B: However, because the coracoclavicular ligaments are intact, the clavicle cannot be displaced significantly upward. C: Following the transection of the coracoclavicular ligaments, the clavicle can be displaced completely above the acromion process. This suggests that the horizontal stability of the AC joint is accomplished by the AC ligaments, and vertical stability is obtained through the coracoclavicular ligaments.
A: With the muscles and AC capsule and ligaments resected and with the coracoclavicular ligaments intact, the clavicle can be displaced anteriorly, as shown, or posteriorly from the articular surface of the acromion. B: However, because the coracoclavicular ligaments are intact, the clavicle cannot be displaced significantly upward. C: Following the transection of the coracoclavicular ligaments, the clavicle can be displaced completely above the acromion process. This suggests that the horizontal stability of the AC joint is accomplished by the AC ligaments, and vertical stability is obtained through the coracoclavicular ligaments.
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Studies have demonstrated that the trapezoid ligament has a greater role in resistance to posterior displacement of the clavicle and the conoid has a greater role in anterior displacement of the clavicle.86,142 The role of the AC joint capsule and ligaments has been studied extensively with respect to distal clavicle resection.17,40,49,50 Posterior abutment of the clavicle against the acromion is avoided with only 5 mm of bone removal. This preserves the capsule and ligaments, maintaining AP stability of the AC joint. Larger resections have been shown to result in excessive posterior translation.13,79 Together, these experiments have led to the following conclusions regarding the AC joint: 
  •  
    The horizontal stability is controlled by the AC ligament and capsule.
  •  
    The vertical stability is controlled by the CC ligaments.
The CC ligament helps to couple glenohumeral abduction/flexion to scapular rotation on the thorax. Full overhead elevation cannot be accomplished without combined and synchronous glenohumeral and scapulothoracic motion.28,72,76 As the clavicle rotates upward, it dictates scapulothoracic rotation by virtue of its attachment to the scapula—the conoid and trapezoid ligaments. 

Motion of the Acromioclavicular Joint

Motion of the AC joint has been a subject of debate. The clavicle rotates superiorly 40 to 50 degrees with elevation of the shoulder. Rockwood et al.127 showed that there was only 5 to 8 degrees of rotation of the clavicle relative to the acromion. Although the clavicle rotates 40 to 50 degrees during full overhead elevation, this rotation is combined with simultaneous scapular rotation rather than with pure AC joint motion.167 This “synchronous scapuloclavicular” motion was originally described by Codman28 and more recently elucidated by Flatow.49 

Acromioclavicular Joint Injury Treatment Options

Nonoperative Treatment of Acromioclavicular Joint Injuries

There is a general consensus supporting nonoperative treatment of Rockwood type I and type II AC joint injuries.34,97 Both type I and type II AC joint injuries are treated in the acute setting with an initial period of immobilization. Although both type I and type II AC injuries are on the lower end of the spectrum, both types may remain symptomatic several years following injury.35,106 Consequently, these lower grade AC joint injuries remain symptomatic for a variety of reasons, such as posttraumatic arthritis, posttraumatic osteolysis of clavicle, recurrent AP subluxation, torn capsular ligaments trapped within the joint, loose pieces of articular cartilage, or detached intra-articular meniscus. In a study by Mouhsine et al.,106 52% of patients with type I and type II injuries were found to be symptomatic at an average of 6 years from injury. Operative treatment of the persistently symptomatic type I and type II AC joint injuries is tailored toward addressing the mechanism behind the symptoms and will be discussed in more detail in the following operative section. In contradistinction to type I and type II AC joint injuries, greater controversy exists regarding the optimal treatment of type III AC joint injuries. Part of the controversy in managing type III AC joint injuries is due to the difficulty in differentiating type III from type V injuries of the AC joint. Furthermore, there has been an oscillating preference in treatment between operative and nonoperative means of handling these AC injuries. Type III AC joint injuries have a completely torn AC and CC ligaments with 25% to 100% superior displacement in comparison to the contralateral shoulder. Type V AC joint injuries have, in addition to complete tears of the AC and CC ligaments, stripping of deltotrapezial fascia that results in greater than 100% superior displacement compared to the contralateral shoulder. With this similarity in the direction of displacement, there has been difficulty in determining not only the correct classification but also the correct treatment. During the 1930s to 1940s, conservative treatment of type III AC joint injuries was predominant. During the 1950s to 1970s, with advances in surgical technique, operative repair became the mainstay for managing these dislocated AC injuries. In a poll study by Powers and Bach121 in 1974, the majority of residency programs across the United States treated type III AC joint injuries with open reduction with 60% using temporary AC fixation and 35% using CC fixation. In the early 1990s, Cox et al.36 polled two groups of orthopedist—one group of specialized sports medicine orthopedists and a second group of chairmen of orthopadic residency programs. Both groups preferred nonoperative management of type III AC joint injuries at 86.4% in the sports medicine specialist group and 72.2% in the orthopedic residency programs. Recently, in 2007, Nissen and Chatterjee112 polled members of the American Orthopaedic Society for Sports Medicine (AOSSM) and residency directors of orthopedic surgery programs who together had inclination toward nonoperative treatment of type III AC injuries. In light of higher levels of evidence, there is a couple of prospective randomized studies of nonoperative versus operative treatment for AC injuries.3,84 In a prospective randomized study, Bannister et al.3 had patients treated operatively with reduction and fixation by a CC screw or treated nonoperatively with a broad arm sling for 2 weeks followed by the same rehabilitation as the operative group. After 4 years of follow-up, the nonoperatively treated group demonstrated quicker regain of movement, quicker return to work and sports, and fewer poor results. However, subgroup analysis of AC dislocations with >2 cm of displacement showed better results in the operatively treated group. In a subsequent prospective randomized study, Larsen et al.84 had patients randomized to nonoperative treatment with a sling or operative treatment using the Phemister procedure that consisted of reduction and fixation of the AC joint with two threaded 2-mm Kirschner wires crossing the joint space followed by suturing of the AC ligament, CC ligament, and surrounding muscle ruptures. From this study, the nonoperatively treated group demonstrated shorter rehabilitation time and the operatively treated group demonstrated higher amount of complications with about half of the operatively treated patients having problems with the metallic device or superficial infections. In comparison between the operative and nonoperative groups, there was no difference in clinical results.84 
Polytrauma patients with AC joint injuries are given more profound consideration toward operative management. In a report by Gallay et al.,54 they showed an AC joint injury, accompanying a polytrauma patient, has greater ramifications with regard to shoulder function as assessed by disease specific and general health outcomes. The type IV, V, and VI AC joint injuries, with attention to the soft tissue disruption and persistently dislocated joint, are generally treated operatively and discussion of these treatments will be deferred to the next section of operative treatment (Table 41-3). 
 
Table 41-3
Acromioclavicular Joint Injuries
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Table 41-3
Acromioclavicular Joint Injuries
Nonoperative Treatment
Indications Relative Contraindications
Type I AC joint injury Chronic symptomatic injury
Type II AC joint injury Chronic symptomatic injury
Type III AC joint injury Failed nonoperative management, athlete, polytrauma, heavy laborers
X
The nonoperative treatment of AC injuries consists of an immobilization device and the so-called skillful neglect.127 Immobilization devices consisted of many variations including slings, adhesive tape strappings, braces, harnesses, traction techniques, and plaster casts.126 Among these immobilization devices, the sling has been the more recently acknowledged and applied method of conservative treatment. In particular, the principle behind the immobilization device is to support the weight of the upper extremity with the intention of reducing the stress placed upon the ligaments of the joint.34 Briefly, during the first week of treatment, the immobilization device, together with ice and analgesics, help reduce the pain and inflammation as a result of the AC joint injury. Similarly, to expedite the healing process, the patient is encouraged to use the injured upper extremity as tolerated. The amount of injury to the AC joint complex and gradation of dislocation does not change from the time of injury. Consequently, the goal of acute phase management is pain control. Following the initial period of immobilization, 1 to 2 weeks depending on grade of dislocation, strengthening exercises are commenced with particular focus on periscapular muscles that are important to shoulder biomechanics.97 However, both heavy lifting and contact sports are avoided during the second phase of treatment with strengthening exercises.97 Athletes who desire an earlier return to sports should be encouraged to use protective padding over the AC joint. An earlier return to sports that sustains a second injury to the AC joint, prior to complete ligament healing, can change a partially subluxated AC joint into a complete AC dislocation. Given this possible sequela, a forewarning must be provided to all athletes wishing to return to play at an earlier time. 

Outcomes

Successful nonoperative treatment of types I to III AC joint injuries has been reported in the literature. Lower-grade energy injuries of the AC joint, classified as type I and II, are in majority treated by nonoperative methods and careful supervision. In the majority of type I and II AC joint injuries, Bjerneld et al.11 showed that patients, at 6 years following injury, treated with a brief period of shoulder immobilization had excellent or good results. In this same study, patients with complete separation of the AC joint, also treated conservatively, showed good to excellent results. Although most patients achieve good outcomes with nonoperative treatment of type I and II AC injuries, Mouhsine et al.106 reported that only 52% of 33 consecutive patients, at a mean of 6.3 years from injury, remained completely asymptomatic. Even among type III AC injuries, several studies have demonstrated good outcomes with conservative measures. For instance, type III AC joint dislocations treated nonoperatively were evaluated in a study by Wojtys and Nelson,165 with a mean follow-up of 2.6 years. In this study, patients returned to work on average 2.1 weeks from injury and the strength and endurance levels of the injured shoulder were comparable to the contralateral uninjured shoulder. Comparatively, the strength and endurance of the affected shoulder with a type III AC injury, conservatively treated, was found to be no different than the performance characteristics of the opposite normal shoulder at an average follow-up of 4.5 years.151 In addition, patients treated conservatively had full range of motion and for this reason neither activities of daily living nor athletic participation was impaired. In a study by Dias42 44 patients with type III AC injury were followed for 5 years after injury. These patients were treated by a broad arm sling for 3 to 5 weeks followed by shoulder mobilization. Subjectively, the majority of patients reported only mild discomfort and no patients had discomfort that subsequently led to a change in occupation. In a follow-up study by Rawes and Dias,123 30 patients of the previously reported cohort (who were treated conservatively by a sling) maintained good outcomes at 12.5 years from the injury despite persistent dislocation of the AC joint. 
Several studies have compared nonoperative treatment to operative treatment of AC injuries. In one of the earlier comparison studies, Galpin et al.55 compared operative treatment, by a Bosworth CC screw, with nonoperative treatment of complete AC dislocations. The results of this study reported equal, if not superior, results in the nonoperatively treated group with regard to earlier return to activities, sports, and work. In both groups, despite the treatment, range of motion and strength were found to be equal. In a more recent study, Gstettner et al.64 retrospectively reviewed patients with type III AC injury treated surgically with a hook plate in comparison to those treated conservatively at a mean follow-up of 34 months. Improved Constant Scores were found in the surgically treated group. In contradistinction, Calvo et al.23 reported no significant difference in results between operative and nonoperative treatment of type III AC joint injury. In particular, the operatively treated AC injuries showed a significantly higher incidence of osteoarthritis and CC ligament ossification. Taft et al.148 compared a group of patients treated nonoperatively with sling, taping, or a Kenny-Howard sling to a group treated operatively with AC or CC fixation. Subjective ratings of pain and stiffness and objective ratings of strength and range of motion were similar in both groups. There was a much higher complication rate in the operative group. Press et al.122 found benefits to both operative and nonoperative treatment, but earlier return to work and sports with nonoperative treatment. There were no significant differences with respect to shoulder range of motion, manual muscle strength, and neurovascular findings between the two groups. In prospective randomized studies between operative and nonoperative treatment of type III AC joint injuries,3,84 patients treated nonoperatively demonstrated a quicker return of function and sustained fewer complications than patients treated operatively. For this reason, the management of type I to III AC injuries, especially in the acute setting, is initially approached with a trial of conservative treatment. 

Operative Treatment of Acromioclavicular Joint Injuries

Indications/Contraindications

The treatment goals for AC joint dislocations include a pain-free shoulder movement in a range of motion arc approaching normal. Various opinions exist regarding the optimal surgical treatment for these injuries. Operative intervention should be clearly discussed with each patient, as the objectives are different for each patient. Type I and II lesions are generally treated conservatively with a sling, ice, and a brief period of immobilization, typically lasting 3 to 7 days. Return to full motion, no or minimal pain, and full function with the ability of self-protection are prerequisites to return to competitive sports. If full function is achieved and only pain remains, a local anesthetic injection can be considered to allow return to sports if timing is crucial. However, no overall consensus exists on treatment for type III dislocations although a trend toward initial nonoperative treatment is presently favored in most cases.125 An undetermined proportion of these conservatively treated patients will have persistent pain and an inability to return to their sport or job. Subsequent surgical stabilization, albeit delayed, has allowed return to sport or work in such cases. It is important to note that to date no high-quality prospective study has demonstrated surgical benefit for the treatment for type III injuries.141,143,149 At our institution, acute type I, II, III, and V injuries are managed with a 6-week course of supervised rehabilitation to maximize rotator cuff strength and the stabilizing function of the periscapular muscles.24,34 In our experience, patients who have failed a minimum 6 weeks of shoulder stabilization–directed physical therapy still have had good to excellent results with delayed surgical reconstruction using a tendon graft.24 In light of the controversy and clear lack of evidence supporting acute surgical management of grade III AC separations, we recommend initial treatment with up to 6 weeks of nonoperative management.24,34,155 It should be noted that altered shoulder biomechanics secondary to complete AC joint displacement was shown in a recent study of patients with type III injuries to result in scapular dyskinesis and, eventually, SICK scapula syndrome (scapular malposition, inferior medial border prominence, coracoid pain and malposition, and dyskinesis of scapular movement). This condition developed in 54% of patients with chronic type III AC dislocations in another study.34,65 Overall, operative treatment is generally the accepted method for active healthy patients with complete AC joint injuries (types IV, V, and VI) because of the significant morbidity associated with the injury pattern that can lead to a persistently dislocated, unstable AC joint, with a change in scapular kinematics, and shoulder dysfunction. 

Surgical Procedure—Historical/Classic Techniques

The surgical treatment for AC joint dislocations has a clear historical progression. Transarticular fixation of the AC joint with pins or wires was one of the first techniques to be described. Fixation was meant to enhance temporary reduction allowing the native soft tissue an opportunity to heal with the AC joint in a reduced position. However, reports of fixation failure, loss of reduction, and disastrous migration of hardware led to abandonment of this technique.96,113 Similarly, the Bosworth “screw suspension” technique was introduced in 1941 as an extra-articular transient fixation device for acute, reducible AC joint dislocations (Fig. 41-25).16 It was meant to provide enough stability to allow CC ligament healing or scar formation to occur. For several reasons, including the contrast between the rigid fixation provided by the screw and the intrinsic motion between the clavicle and (coracoid) scapula, hardware failure, migration, and coracoid fractures were reported with this construct. Taking a similar approach, alternative “CC suspension” constructs appeared in the literature; Dacron grafts, wires, and various types of sutures.127,141 The concept was to allow for motion, with a less rigid construct, but provide enough fixation to hold the CC distance reduced and allow for AC- and CC-ligament healing. In 1972, Weaver and Dunn161 published their technique of distal clavicle resection and transfer of the CA ligament to the distal clavicle to restore and reconstruct the CC ligaments and treat acute and chronic AC joint instability. Over the years, numerous modifications to this technique have been described.127 This technique represents an open procedure, which uses the detached CA ligament as a retaining structure for the distal clavicle. The modification of this nonanatomic technique involves an additional suture construct for increased primary stability (Fig. 41-26).161 This approach, along with various technical modifications, is still widely utilized to reconstruct the CC ligaments, although it is considered inferior biomechanically compared to the other techniques.98,99,150 Historically, although good to excellent results of this procedure have been reported, 75%,127 the initial strength of the CA ligament after transfer has been shown to be only 25% of the normal, intact CC ligaments, and it does not recreate horizontal plane stability.87 In a recent cadaveric model, the ultimate load to failure of the modified Weaver–Dunn was found to be 39% less than control.150 There can be an upward rate of 30% of recurrent instability with this technique, typically in the anterior–posterior direction at the AC joint.98,99,162 From a biomechanical perspective, the importance of the AC ligaments in controlling superior and horizontal translations has been demonstrated.52,79 Superior clavicle plates with lateral hooks or “AC hook plates” have been reported in the literature since the 1980s with mixed results.140 There have been a few modifications to the plate to lower its profile or add “locking screw technology” but the concept remains the same. This type of fixation holds the CC distance in a reduced position by “hooking” under the acromion elevating the glenohumeral joint (Fig. 41-27). Most reported cases involving superior clavicle “hook” plates are used in patients with chronic dislocations often with concomitant AC joint arthrosis.140 Rates of good or excellent results ranging between 60% and 94% have been reported, but complications of this technique include acromial fracture or erosion and hardware irritation necessitating removal of the plate or of the tab on the distal end articulating under the acromion. Recently reported was a retrospective study of chronic AC dislocations treated by a Weaver–Dunn procedure in which constructs augmented with PDS no. 1 braided suture around the coracoid were compared to a hook plate (Synthes, Solothurn, Switzerland). Patients treated with the hook plate augmentation did not have increased AC joint stability after plate removal, and although not powered to detect significance there was a trend to lower Constant Scores in the hook plate group. More importantly, the hook plate group had more pain related to the plate and all required surgical removal.15 Other complications associated with hook plates have been recently reported, including chronic irritation in the subacromial space resulting in a persistent pain syndrome, and plate removal77 or sustained acromial osteolysis and fractures.27 In the study reported by Kienast et al.,77 there was an overall complication rate of 10.6% with a 2% redislocation rate. A similar study reported a 12% redislocation rate. 
Figure 41-25
Postoperative anteroposterior radiograph of the shoulder with a Bosworth screw in place.
 
Note that the AC joint has been reduced and the coarse lag threads of the screw are well seated into the coracoid process.
Note that the AC joint has been reduced and the coarse lag threads of the screw are well seated into the coracoid process.
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Figure 41-25
Postoperative anteroposterior radiograph of the shoulder with a Bosworth screw in place.
Note that the AC joint has been reduced and the coarse lag threads of the screw are well seated into the coracoid process.
Note that the AC joint has been reduced and the coarse lag threads of the screw are well seated into the coracoid process.
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Figure 41-26
Transfer of the acromial attachment of the coracoacromial ligament.
 
A: A small portion of the anterior deltoid is reflected from the anterior acromion to expose the coracoacromial ligament. B: The ligament is released from the acromion and sutures are placed in the end. C: Two unicortical drill holes are placed in the posterosuperior surface of the distal clavicle, exiting through the medullary canal. D: The coracoacromial ligament is transferred to the medullary canal. The sutures are placed through the drill holes and tied over the top of the clavicle.
A: A small portion of the anterior deltoid is reflected from the anterior acromion to expose the coracoacromial ligament. B: The ligament is released from the acromion and sutures are placed in the end. C: Two unicortical drill holes are placed in the posterosuperior surface of the distal clavicle, exiting through the medullary canal. D: The coracoacromial ligament is transferred to the medullary canal. The sutures are placed through the drill holes and tied over the top of the clavicle.
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Figure 41-26
Transfer of the acromial attachment of the coracoacromial ligament.
A: A small portion of the anterior deltoid is reflected from the anterior acromion to expose the coracoacromial ligament. B: The ligament is released from the acromion and sutures are placed in the end. C: Two unicortical drill holes are placed in the posterosuperior surface of the distal clavicle, exiting through the medullary canal. D: The coracoacromial ligament is transferred to the medullary canal. The sutures are placed through the drill holes and tied over the top of the clavicle.
A: A small portion of the anterior deltoid is reflected from the anterior acromion to expose the coracoacromial ligament. B: The ligament is released from the acromion and sutures are placed in the end. C: Two unicortical drill holes are placed in the posterosuperior surface of the distal clavicle, exiting through the medullary canal. D: The coracoacromial ligament is transferred to the medullary canal. The sutures are placed through the drill holes and tied over the top of the clavicle.
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Figure 41-27
Superior clavicle hook plate.
 
(With permission From Iannotti JP, Miniaci A, Williams G, Zuckerman DJ. Disorders of the Shoulder: Sports Injuries. Philadelphia, PA: Lippincott Williams & Wilkins; 2013.)
(With permission From Iannotti JP, Miniaci A, Williams G, Zuckerman DJ. Disorders of the Shoulder: Sports Injuries. Philadelphia, PA: Lippincott Williams & Wilkins; 2013.)
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Figure 41-27
Superior clavicle hook plate.
(With permission From Iannotti JP, Miniaci A, Williams G, Zuckerman DJ. Disorders of the Shoulder: Sports Injuries. Philadelphia, PA: Lippincott Williams & Wilkins; 2013.)
(With permission From Iannotti JP, Miniaci A, Williams G, Zuckerman DJ. Disorders of the Shoulder: Sports Injuries. Philadelphia, PA: Lippincott Williams & Wilkins; 2013.)
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Anatomic Approaches

The first attempt at the reconstruction of the CC ligaments was reported in 1942 by Vargus, describing transfer of part of the conjoined tendon anterior to the clavicle. Anatomic reconstruction of the native CC ligaments and AC ligaments represents an improved understanding of the biomechanics in this area with the possibility of improved surgical outcomes. The anatomic coracoclavicular ligament reconstruction (ACCR) technique described here attempts to restore the biomechanics of the AC joint complex for the treatment of painful or unstable dislocations.5,17,18,21,33 

Chronic Acromioclavicular Injuries

Patients with type I and II AC joint injuries may develop late degenerative changes.9,35,106 The meniscus and articular cartilage often sustain an injury that leads to these degenerative changes. Chronic pain after type I and II injuries is treated with mild analgesics such as nonsteroidal anti-inflammatory medication, avoidance of painful activity or positions, and intra-articular injection with corticosteroid preparations. Many will resolve with this conservative treatment. 
Patients with chronic type I injuries who do not respond to conservative care may require operative excision of the distal clavicle to provide relief of pain. This can be performed using an open or an arthroscopic technique.51,56,107,144 The important aspect of either technique is preservation or repair of the AC joint capsule to maintain AP stability of the joint.17 Resections should be limited to less than 10 mm of distal clavicle as to limit the disruption of the superior and posterior capsular/ligament structures. Violation of these structures can lead to residual anterior–posterior clavicle instability and pain. 
In patients with chronic pain after type II AC sprains, the initial conservative regimen is the same as for type I injuries. If conservative, symptomatic treatment fails, surgery may be indicated. Isolated distal clavicle excision after a type II injury may fail because of AP instability of the distal clavicle and resultant posterior abutment of the clavicle on the scapular spine. Therefore, the patient should be examined carefully for increased AP translation of the clavicle relative to the acromion during preoperative examination. If excessive AP instability exists, distal clavicle excision should be combined with AC capsular reconstruction or coracoacromial ligament transfer.161 
Chronic pain and instability after complete AC dislocations (types III, IV, and V) should not be treated with isolated distal clavicle excision. This merely shortens the clavicle without stabilizing it and is often associated with persistent postoperative symptoms. Therefore, distal clavicle excision should be combined with stabilization in chronic, symptomatic, and complete AC injuries. The most popular reconstructive procedure is transfer of the acromial attachment of the coracoacromial ligament to the resected surface of the distal clavicle and concurrent CC stabilization. CC stabilization greatly increases the strength of the construct.44,66,68,74,122 

Author’s Preferred Treatment for Acromioclavicular Joint Injuries

 
 
Acute Treatment
 

Initial treatment is with a sling placed to fully support and elevate the arm and to take tension off the injured ligaments. In lower-grade injuries shoulder activity can be initiated at 1 week and is typically pain free by 2 to 3 weeks. In higher-grade injuries formal physical therapy to address shoulder muscle weakness and periscapular strengthening is started at 2 weeks. Heavy stresses, lifting, and contact sports should be delayed until there is a full range of motion and no pain to joint palpation. This process can take upto 2 to 4 weeks and is dependent upon AC joint separation grade, patient pre-injury condition and…., as well as patient pain tolerance. All patients are given a trial of 6 to 8 weeks of nonoperative care until surgical intervention is considered unless neurologic or skin issues dictate earlier intervention. Contact sports can resume at 4 to 6 weeks and is dictated by pain with activity. To date no study has demonstrated a progression of AC separation with early return to sport but pain with collision sports is certainly a limitation and can be addressed by preactivity injections to the AC joint—with or without corticosteroids.

 

Anatomic reconstruction of the native CC ligaments and AC ligaments represents an improved understanding of the biomechanics in this area with the attempt to improve surgical outcomes. Although still controversial, the authors believe that all stabilizing structures of the AC joint complex should be reconstructed to achieve optimal result. The ACCR technique attempts to restore the biomechanics of the AC joint complex as treatment for painful or unstable dislocations. The rationale of this technique is to reconstruct both CC ligaments by anatomically fixing a tendon graft in two clavicle tunnels placed in the anatomic insertion site of the conoid and trapezoid ligaments. In addition, the AC ligaments are reconstructed with the remaining limb of the graft exiting the more lateral trapezoid tunnel. This technique has been previously reported during various stages of its development and this description represents the current version.24,98,125

 
Patient Positioning
 

The procedure is performed in the beach-chair position with the hip flexed to 60 to 70 degrees, and the patient positioned far lateral on the operating table to allow the arm to fall into extension. This facilitates exposure and mobilization of the shoulder for scapula reduction to the clavicle. A small towel bump is placed along the medial border of the scapula to prevent protraction of the scapula. In addition, this elevates the torso away from the table thereby improving access to the clavicle for drilling the bone tunnels. Gently rotating the patient’s head away from the operative field with some extension aids in exposure (Fig. 41-28). It is important not to be aggressive with this maneuver to limit excessive tension to the brachial plexus during the procedure. The patient is secured with a safety belt and 3-in cloth tape around the chest. It is important to drape a wide operative field; from the SC joint, to the nipple line, up the neck to the base of the ear, and extends several inches behind the posterior aspect of the clavicle. Before prepping, the miniature C-arm is prepositioned to allow imaging intraoperatively, if needed. Imaging can be obtained by advancing the image machine from above, in line with the AP image from the patient’s head direction. In addition, a comparative Zanca view is made of the normal AC joint to act as a reference for the measurement of the intact CC distance.

 
Figure 41-28
ACCR technique: Patient positioning.
 
Note the far lateral position with shoulder free to extend, small scapula bump along medial scapula border, and head position extended and rotated away from operative side. (With permission from Iannotti JP, Miniaci A, Williams G, Zuckerman DJ. Disorders of the Shoulder: Sports Injuries. Philadelphia, PA: Lippincott Williams & Wilkins; 2013.)
Note the far lateral position with shoulder free to extend, small scapula bump along medial scapula border, and head position extended and rotated away from operative side. (With permission from Iannotti JP, Miniaci A, Williams G, Zuckerman DJ. Disorders of the Shoulder: Sports Injuries. Philadelphia, PA: Lippincott Williams & Wilkins; 2013.)
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Figure 41-28
ACCR technique: Patient positioning.
Note the far lateral position with shoulder free to extend, small scapula bump along medial scapula border, and head position extended and rotated away from operative side. (With permission from Iannotti JP, Miniaci A, Williams G, Zuckerman DJ. Disorders of the Shoulder: Sports Injuries. Philadelphia, PA: Lippincott Williams & Wilkins; 2013.)
Note the far lateral position with shoulder free to extend, small scapula bump along medial scapula border, and head position extended and rotated away from operative side. (With permission from Iannotti JP, Miniaci A, Williams G, Zuckerman DJ. Disorders of the Shoulder: Sports Injuries. Philadelphia, PA: Lippincott Williams & Wilkins; 2013.)
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Surgical Approach
 

We use a direct approach with a saber incision made over the clavicle approximately 3.5 cm medial to the AC joint. The incision starts posterior to the clavicle, crossing just medial to the tip of the coracoid process, and extending inferior enough to ensure visualization of the coracoid for graft passage (Fig. 41-29). The incision should be long enough to accommodate AC joint visualization with Gelpi retractor perpendicular to the incision. This incision is medial to the approach typically used for the Weaver–Dunn reconstruction. Needle tip electrocautery is used to obtain hemostasis and carry the dissection down to the deltotrapezial fascia. Generous skin flaps are raised directly above the fascia to improve visualization. This is well tolerated about the shoulder because of the vascularity of the region. The deltotrapezial fascia is then elevated from the distal clavicle as full-thickness flaps (Fig. 41-30). The fascia is incised in line with the natural demarcation between the trapezius insertion to the posterior aspect of the clavicle and the deltoid origin on the anterior clavicle. Dissection of the fascia should extend far enough medially to expose the conoid ligament insertion, approximately 46.3 mm ± 5 mm from the distal end of the clavicle.98,125,127 Skeletonizing the clavicle can be done sharply with an elevator or electrocautery, but maintaining full-thickness periosteal flaps is critical to obtaining a good closure (Fig. 41-31). Tagging stitches are placed in the flaps to aid in retraction and then facilitate accurate reapproximation at closure. It is important to note that the deltoid has an insertion on the undersurface of the clavicle and care should be given to ensure that the deltoid is not violated. This is done by carefully and slowly peeling the deltoid and trapezius off the clavicle with the periosteum, understanding the clavicle is a tubular structure and to follow the curve with the elevator inferior and not to transect the deltoid from the anterior edge. Gelpi retractors are used to retract the flaps parallel and perpendicular to the incision with alternating pressure to facilitate exposure of the AC joint or coracoid base. The distal end of the clavicle is exposed to allow for reduction and preservation of any AC capsule/ligaments if possible. Reduction of the AC joint is accomplished by elevating the scapulohumeral complex to the clavicle by supporting the elbow and scapula. Visual inspection is usually adequate for assessing reduction; however, a mini C-arm can be used intraoperatively to confirm the reduction. An image of the uninjured shoulder can be saved or printed for comparative CC distance measurements. In chronic AC dislocations, there can be significant scar tissue inferior to the AC joint which needs to be removed to allow adequate reduction.

 
Figure 41-29
 
The vertical incision is made along Langer lines, centered on the clavicle approximately 3.5 cm medial to the AC joint, in a curvilinear fashion starting from the posterior clavicle to just medial of the coracoid process. (With permission from Iannotti JP, Miniaci A, Williams G, Zuckerman DJ. Disorders of the Shoulder: Sports Injuries. Philadelphia, PA: Lippincott Williams & Wilkins; 2013.)
The vertical incision is made along Langer lines, centered on the clavicle approximately 3.5 cm medial to the AC joint, in a curvilinear fashion starting from the posterior clavicle to just medial of the coracoid process. (With permission from Iannotti JP, Miniaci A, Williams G, Zuckerman DJ. Disorders of the Shoulder: Sports Injuries. Philadelphia, PA: Lippincott Williams & Wilkins; 2013.)
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Figure 41-29
The vertical incision is made along Langer lines, centered on the clavicle approximately 3.5 cm medial to the AC joint, in a curvilinear fashion starting from the posterior clavicle to just medial of the coracoid process. (With permission from Iannotti JP, Miniaci A, Williams G, Zuckerman DJ. Disorders of the Shoulder: Sports Injuries. Philadelphia, PA: Lippincott Williams & Wilkins; 2013.)
The vertical incision is made along Langer lines, centered on the clavicle approximately 3.5 cm medial to the AC joint, in a curvilinear fashion starting from the posterior clavicle to just medial of the coracoid process. (With permission from Iannotti JP, Miniaci A, Williams G, Zuckerman DJ. Disorders of the Shoulder: Sports Injuries. Philadelphia, PA: Lippincott Williams & Wilkins; 2013.)
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Figure 41-30
ACCR technique.
 
Right shoulder taken from lateral looking medial. Skeletonizing of the clavicle is started with electrocautery, then thick subperiosteal flaps are raised sharply with elevator to ensure the trapezius and deltoid attachments are elevated off in a sleeve, superior and inferior. Tagging stitches can be placed to aid in tight closure of this layer as a critical step during closure. (With permission from Iannotti JP, Miniaci A, Williams G, Zuckerman DJ. Disorders of the Shoulder: Sports Injuries. Philadelphia, PA: Lippincott Williams & Wilkins; 2013.)
Right shoulder taken from lateral looking medial. Skeletonizing of the clavicle is started with electrocautery, then thick subperiosteal flaps are raised sharply with elevator to ensure the trapezius and deltoid attachments are elevated off in a sleeve, superior and inferior. Tagging stitches can be placed to aid in tight closure of this layer as a critical step during closure. (With permission from Iannotti JP, Miniaci A, Williams G, Zuckerman DJ. Disorders of the Shoulder: Sports Injuries. Philadelphia, PA: Lippincott Williams & Wilkins; 2013.)
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Figure 41-30
ACCR technique.
Right shoulder taken from lateral looking medial. Skeletonizing of the clavicle is started with electrocautery, then thick subperiosteal flaps are raised sharply with elevator to ensure the trapezius and deltoid attachments are elevated off in a sleeve, superior and inferior. Tagging stitches can be placed to aid in tight closure of this layer as a critical step during closure. (With permission from Iannotti JP, Miniaci A, Williams G, Zuckerman DJ. Disorders of the Shoulder: Sports Injuries. Philadelphia, PA: Lippincott Williams & Wilkins; 2013.)
Right shoulder taken from lateral looking medial. Skeletonizing of the clavicle is started with electrocautery, then thick subperiosteal flaps are raised sharply with elevator to ensure the trapezius and deltoid attachments are elevated off in a sleeve, superior and inferior. Tagging stitches can be placed to aid in tight closure of this layer as a critical step during closure. (With permission from Iannotti JP, Miniaci A, Williams G, Zuckerman DJ. Disorders of the Shoulder: Sports Injuries. Philadelphia, PA: Lippincott Williams & Wilkins; 2013.)
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Figure 41-31
ACCR technique.
 
Right shoulder, picture taken from posterior: Medial is left. Tunnel positions are measured and marked: Conoid (at least 45 mm from distal clavicle), using conoid tunnel mark as reference the trapezoid tunnel position is marked to ensure at least 25 mm of bone bridge between tunnels and at least 4 mm from the clavicle edge toward the midline (20 to 25 mm from distal clavicle). (With permission from Iannotti JP, Miniaci A, Williams G, Zuckerman DJ. Disorders of the Shoulder: Sports Injuries. (Philadelphia, PA: Lippincott Williams & Wilkins; 2013.)
Right shoulder, picture taken from posterior: Medial is left. Tunnel positions are measured and marked: Conoid (at least 45 mm from distal clavicle), using conoid tunnel mark as reference the trapezoid tunnel position is marked to ensure at least 25 mm of bone bridge between tunnels and at least 4 mm from the clavicle edge toward the midline (20 to 25 mm from distal clavicle). (With permission from Iannotti JP, Miniaci A, Williams G, Zuckerman DJ. Disorders of the Shoulder: Sports Injuries. (Philadelphia, PA: Lippincott Williams & Wilkins; 2013.)
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Figure 41-31
ACCR technique.
Right shoulder, picture taken from posterior: Medial is left. Tunnel positions are measured and marked: Conoid (at least 45 mm from distal clavicle), using conoid tunnel mark as reference the trapezoid tunnel position is marked to ensure at least 25 mm of bone bridge between tunnels and at least 4 mm from the clavicle edge toward the midline (20 to 25 mm from distal clavicle). (With permission from Iannotti JP, Miniaci A, Williams G, Zuckerman DJ. Disorders of the Shoulder: Sports Injuries. (Philadelphia, PA: Lippincott Williams & Wilkins; 2013.)
Right shoulder, picture taken from posterior: Medial is left. Tunnel positions are measured and marked: Conoid (at least 45 mm from distal clavicle), using conoid tunnel mark as reference the trapezoid tunnel position is marked to ensure at least 25 mm of bone bridge between tunnels and at least 4 mm from the clavicle edge toward the midline (20 to 25 mm from distal clavicle). (With permission from Iannotti JP, Miniaci A, Williams G, Zuckerman DJ. Disorders of the Shoulder: Sports Injuries. (Philadelphia, PA: Lippincott Williams & Wilkins; 2013.)
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Bone Tunnel Placement
 

Placement of clavicle bone tunnels for graft reconstruction of the CC ligaments is designed to reproduce their anatomic positions in relation to the distal clavicle. Smooth guide pins for the 5-mm–cannulated reamer are placed at the anatomic location corresponding to the conoid and trapezoid ligaments with a Cobb elevator or retractor inferior to the clavicle for protection. Guide pin placement for the conoid ligament tunnel is placed 45 mm medial to the distal clavicle and posterior to the midline of the clavicle in the coronal plane (Fig. 41-32). The bone density in fresh cadaveric specimens reveals the more lateral bone has less mineralization with softer bone for fixation. Thus, the surgeon should error on being slightly more medial to take advantage of improved bone density in this location. A secondary anatomic reference is the conoid tubercle, which can be palpated on the posterior surface of the clavicle. A second pin is placed lateral to the conoid pin by 20 mm and just anterior to the clavicle midline again in the coronal plane, this corresponds to the trapezoid ligament tunnel and should not be less than 15 mm from the end of the clavicle. Again it is important to be no less than 20 to 25 mm from the distal clavicle for bone quality and a minimum of 20-mm bone bridge between the tunnels to prevent fracture. Bone tunnels must also be placed at least 3 mm from the edge of the clavicle toward the midline. The objective is to ensure enough bone between the tunnel and the edge of the clavicle to prevent blowout fracture of the cortical bone edge during interference screw placement. For tunnel preparation, power reaming is used to create the tunnel but power is then shut off for reamer extraction, the “ream-in, pull-out” technique, to ensure the tunnel is not made eccentrically, optimizing fixation of the graft. In summary, the reamer is advanced in under power with care not to dive through the far cortex; the drill is stopped and then disconnected while it is pulled out. The goal is to make the tunnel as tight as possible and therefore graft passage should be somewhat difficult. In our experience, the complication of clavicle fracture has not been observed in patients or during cadaver experiments with tunnels 5 mm or less. A secure fit between the graft and tunnel is a critical aspect of the procedure. Interference fixation is obtained with implantable polyetheretherketone (PEEK) polymer screws, (an inert, MRI compatible material). These screws have a higher pull-out strength than bioabsorbable screws, but do not cut or rip the tissue as can occur with metal screws. The bone tunnels must be tapped prior to placement of the PEEK screws. This allows easier screw placement, minimizing graft “creep” with interference screw tightening, and decreases the torque needed to seat the screw, lowering stress on the bone tunnel. Oversizing of the tunnel impairs fixation and can be a cause of failure. In the event of cortical fracture that does not allow PEEK screw fixation, the graft limbs can be passed over the clavicle and then sutured together on top of the clavicle. In the specific situation of a type IV AC joint dislocation with significant posterior displacement of the clavicle, the bone tunnel positions can be adjusted more posterior to the midclavicle line. This provides an anterior force vector in the reconstruction that improves the reduction. However, the minimal bone bridge and cortical edge distances must still be maintained. If additional anterior reduction force is needed, the two ends of the graft should not be crossed before being shuttled through the clavicle bone tunnels (Fig. 41-33).

 
Figure 41-32
ACCR technique.
 
Threaded guide pins for a 5.5-mm cannulated drill are placed corresponding to anatomic position. Care is taken to prevent fracture or cortical blowout by ensuring at least. 3-mm from cortical edge. (With permission from Iannotti JP, Miniaci A, Williams G, Zuckerman DJ. Disorders of the Shoulder: Sports Injuries. Philadelphia, PA: Lippincott Williams & Wilkins; 2013.)
Threaded guide pins for a 5.5-mm cannulated drill are placed corresponding to anatomic position. Care is taken to prevent fracture or cortical blowout by ensuring at least. 3-mm from cortical edge. (With permission from Iannotti JP, Miniaci A, Williams G, Zuckerman DJ. Disorders of the Shoulder: Sports Injuries. Philadelphia, PA: Lippincott Williams & Wilkins; 2013.)
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Figure 41-32
ACCR technique.
Threaded guide pins for a 5.5-mm cannulated drill are placed corresponding to anatomic position. Care is taken to prevent fracture or cortical blowout by ensuring at least. 3-mm from cortical edge. (With permission from Iannotti JP, Miniaci A, Williams G, Zuckerman DJ. Disorders of the Shoulder: Sports Injuries. Philadelphia, PA: Lippincott Williams & Wilkins; 2013.)
Threaded guide pins for a 5.5-mm cannulated drill are placed corresponding to anatomic position. Care is taken to prevent fracture or cortical blowout by ensuring at least. 3-mm from cortical edge. (With permission from Iannotti JP, Miniaci A, Williams G, Zuckerman DJ. Disorders of the Shoulder: Sports Injuries. Philadelphia, PA: Lippincott Williams & Wilkins; 2013.)
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Figure 41-33
ACCR technique: Graft construct and medial fixation.
 
A: Cadaver right shoulder looking from anterior at construct around coracoid base figure of eight pattern. B: Artist rendering of ACCR construct, magnification of medial construct. C, D: Intraoperative photo of right shoulder from above. Fixation of the graft into the bone tunnels. Bone tunnels are tapped prior to graft passage. Graft limbs are kept under tension while the PEEK screw is inserted. (With permission from Iannotti JP, Miniaci A, Williams G, Zuckerman DJ. Disorders of the Shoulder: Sports Injuries. Philadelphia, PA: Lippincott Williams & Wilkins; 2013.)
A: Cadaver right shoulder looking from anterior at construct around coracoid base figure of eight pattern. B: Artist rendering of ACCR construct, magnification of medial construct. C, D: Intraoperative photo of right shoulder from above. Fixation of the graft into the bone tunnels. Bone tunnels are tapped prior to graft passage. Graft limbs are kept under tension while the PEEK screw is inserted. (With permission from Iannotti JP, Miniaci A, Williams G, Zuckerman DJ. Disorders of the Shoulder: Sports Injuries. Philadelphia, PA: Lippincott Williams & Wilkins; 2013.)
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A: Cadaver right shoulder looking from anterior at construct around coracoid base figure of eight pattern. B: Artist rendering of ACCR construct, magnification of medial construct. C, D: Intraoperative photo of right shoulder from above. Fixation of the graft into the bone tunnels. Bone tunnels are tapped prior to graft passage. Graft limbs are kept under tension while the PEEK screw is inserted. (With permission from Iannotti JP, Miniaci A, Williams G, Zuckerman DJ. Disorders of the Shoulder: Sports Injuries. Philadelphia, PA: Lippincott Williams & Wilkins; 2013.)
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Figure 41-33
ACCR technique: Graft construct and medial fixation.
A: Cadaver right shoulder looking from anterior at construct around coracoid base figure of eight pattern. B: Artist rendering of ACCR construct, magnification of medial construct. C, D: Intraoperative photo of right shoulder from above. Fixation of the graft into the bone tunnels. Bone tunnels are tapped prior to graft passage. Graft limbs are kept under tension while the PEEK screw is inserted. (With permission from Iannotti JP, Miniaci A, Williams G, Zuckerman DJ. Disorders of the Shoulder: Sports Injuries. Philadelphia, PA: Lippincott Williams & Wilkins; 2013.)
A: Cadaver right shoulder looking from anterior at construct around coracoid base figure of eight pattern. B: Artist rendering of ACCR construct, magnification of medial construct. C, D: Intraoperative photo of right shoulder from above. Fixation of the graft into the bone tunnels. Bone tunnels are tapped prior to graft passage. Graft limbs are kept under tension while the PEEK screw is inserted. (With permission from Iannotti JP, Miniaci A, Williams G, Zuckerman DJ. Disorders of the Shoulder: Sports Injuries. Philadelphia, PA: Lippincott Williams & Wilkins; 2013.)
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A: Cadaver right shoulder looking from anterior at construct around coracoid base figure of eight pattern. B: Artist rendering of ACCR construct, magnification of medial construct. C, D: Intraoperative photo of right shoulder from above. Fixation of the graft into the bone tunnels. Bone tunnels are tapped prior to graft passage. Graft limbs are kept under tension while the PEEK screw is inserted. (With permission from Iannotti JP, Miniaci A, Williams G, Zuckerman DJ. Disorders of the Shoulder: Sports Injuries. Philadelphia, PA: Lippincott Williams & Wilkins; 2013.)
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Graft Preparation and Passage
 

Graft options include a semitendinosus allograft or autograft. Anterior tibialis allograft is another suitable graft source but must be trimmed significantly because it is often quite thick. Semitendinosus allograft is our preferred graft for numerous reasons; simplification of patient positioning, no donor site morbidity, decreased operative time, and consistency in the graft tissue size. To date, there has been no reported cases of infectious transmission in soft tissue only allografts.6,46 Semitendinosus allograft typically comes in diameters ≥5 mm and minimum lengths of 230 mm, which is sufficient for this reconstructive technique. The minimal length needed to ensure graft available for AC ligament reconstruction is approximately 110 mm. The graft is prepared with a continuous running locked stitch of high-strength nonabsorbable suture. These sutures are then pulled tightly to help tubularize the flat end of the tendon while compressing the looped end, so that the tendon is of uniform diameter after preparation. Frayed graft ends are excised to allow easy passage. The graft is passed beneath the coracoid using either a shuttling stitch and a curved clamp such as the Satinsky aortic cross clamp or a curved suture passing device (Fig. 41-33). A no.2 high-strength nonabsorbable suture is passed with the graft to provide additional nonbiologic fixation. This suture will eventually be shuttled through the cannulation of the interference screw and when tied provides additional fixation during healing of the graft. The graft is passed from medial to lateral under direct visualization, to minimize the risk of injury to the underlying neurovascular structures.

 

After passing the graft and no.2 suture beneath the coracoid, the limbs of the graft are crossed in figure of eight fashion before being shuttled through the bone tunnels from inferior to superior direction (Fig. 41-33). A commercial or homemade suture passer is used to assist in graft placement through the bone tunnels, beginning with the conoid (posteromedial) tunnel. The graft is then cyclically loaded by pulling up on both ends to remove any slack, and seesawed back and forth to allow for easy passage. The graft is arranged so that a shorter limb of approximately 2 cm exits the conoid tunnel. The remaining length of the graft exits the trapezoid tunnel. This longer limb will be used later to reinforce the AC joint and recreate the superior and anterior AC ligaments (Fig. 41-33).

 
Acromioclavicular Joint Reduction and Graft Fixation
 

Reduction of the AC joint is accomplished by elevating the scapulohumeral complex to the clavicle by having an assistant push on the elbow. The quality of reduction can be assessed under direct visualization, but radiographic assessment may also be used. Measurement of the CC distance can be made intraoperatively and compared to the uninjured side prior to graft fixation. An anatomical reduction of the AC joint is critical. While an assistant maintains the reduction, the grafts are secured with interference screws. Interference fixation of the grafts within the bone tunnels is done with a 5.5- × 8-mm PEEK screw placed in the anterior aspect of the tunnel while tension is maintained on the graft (Fig. 41-33). One limb of the no.2 high-strength suture is passed with the graft beneath the coracoid and through the respective tunnels. It is then passed through the first interference screw used to fix the conoid portion of the reconstruction. Fixation of the posteromedial graft, corresponding to the conoid ligament tunnel, is done first. After interference screw placement, the other limb of the graft exiting the AP bone tunnel, representing the trapezoid ligament, is cyclically tensioned to remove any residual slack and held under maximal tension while the second interference screw is placed in the anterior aspect of the tunnel (Fig. 41-33). Prior to secure fixation and placement of the interference screw the other limb of the no. 2 high-strength nonabsorbable end suture is brought through the cannulation hole of the PEEK screw (Fig. 41-34). After fixation of the graft in both tunnels, both limbs of the no.2 suture are tied on the superior aspect of the clavicle. Secondary graft fixation is accomplished by suturing the shorter limb of graft exiting the posterior medial tunnel to the base of the long graft limb exiting anterior lateral tunnel to create a closed figure of eight loop (Fig. 41-34). The remnants of the AC joint capsule/ligaments are identified and repaired with figure of eight stitches using absorbable suture. This repair is augmented with the longer limb of graft exiting the anterior lateral bone tunnel. The graft should have enough length to be looped over the top of the AC joint to reinforce this repair and reconstruct the anterior AC ligaments, important for anterior–posterior stability (Fig. 41-35). We use a free needle and tie this as a horizontal mattress securing periosteum and remnants of the original AC ligament to make a band across the top part of the joint. With sufficient graft length, the posterior AC ligament repair is reinforced by looping the graft posterior and incorporating the trapezial fascia with high-strength nonabsorbable suture on the acromial side of the joint.

 
Figure 41-34
ACCR technique.
 
Fixation at CC ligament reconstruction. A: After graft is wrapped around the coracoid elbow in crossing fashion the two ends are brought up through there corresponding tunnels such that the conoid tunnel graft is shorter than the trapezoid tunnel graft. Length of the conoid tunnel graft should be sufficient to span the bone bridge between tunnels and an additional 20 to 30 mm to suture to the base of the trapezoid tunnel graft for fixation. The remaining graft length should be exiting from the trapezoid tunnel and sufficient to span the 30 mm to the AC joint and augment the AC capsule/ligament repair superiorly. B: No. 2 high-strength nonabsorbable end suture is brought through the cannulation hole of the PEEK screw and tied over the clavicle. (With permission from Iannotti JP, Miniaci A, Williams G, Zuckerman DJ. Disorders of the Shoulder: Sports Injuries. Philadelphia, PA: Lippincott Williams & Wilkins; 2013.)
Fixation at CC ligament reconstruction. A: After graft is wrapped around the coracoid elbow in crossing fashion the two ends are brought up through there corresponding tunnels such that the conoid tunnel graft is shorter than the trapezoid tunnel graft. Length of the conoid tunnel graft should be sufficient to span the bone bridge between tunnels and an additional 20 to 30 mm to suture to the base of the trapezoid tunnel graft for fixation. The remaining graft length should be exiting from the trapezoid tunnel and sufficient to span the 30 mm to the AC joint and augment the AC capsule/ligament repair superiorly. B: No. 2 high-strength nonabsorbable end suture is brought through the cannulation hole of the PEEK screw and tied over the clavicle. (With permission from Iannotti JP, Miniaci A, Williams G, Zuckerman DJ. Disorders of the Shoulder: Sports Injuries. Philadelphia, PA: Lippincott Williams & Wilkins; 2013.)
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Figure 41-34
ACCR technique.
Fixation at CC ligament reconstruction. A: After graft is wrapped around the coracoid elbow in crossing fashion the two ends are brought up through there corresponding tunnels such that the conoid tunnel graft is shorter than the trapezoid tunnel graft. Length of the conoid tunnel graft should be sufficient to span the bone bridge between tunnels and an additional 20 to 30 mm to suture to the base of the trapezoid tunnel graft for fixation. The remaining graft length should be exiting from the trapezoid tunnel and sufficient to span the 30 mm to the AC joint and augment the AC capsule/ligament repair superiorly. B: No. 2 high-strength nonabsorbable end suture is brought through the cannulation hole of the PEEK screw and tied over the clavicle. (With permission from Iannotti JP, Miniaci A, Williams G, Zuckerman DJ. Disorders of the Shoulder: Sports Injuries. Philadelphia, PA: Lippincott Williams & Wilkins; 2013.)
Fixation at CC ligament reconstruction. A: After graft is wrapped around the coracoid elbow in crossing fashion the two ends are brought up through there corresponding tunnels such that the conoid tunnel graft is shorter than the trapezoid tunnel graft. Length of the conoid tunnel graft should be sufficient to span the bone bridge between tunnels and an additional 20 to 30 mm to suture to the base of the trapezoid tunnel graft for fixation. The remaining graft length should be exiting from the trapezoid tunnel and sufficient to span the 30 mm to the AC joint and augment the AC capsule/ligament repair superiorly. B: No. 2 high-strength nonabsorbable end suture is brought through the cannulation hole of the PEEK screw and tied over the clavicle. (With permission from Iannotti JP, Miniaci A, Williams G, Zuckerman DJ. Disorders of the Shoulder: Sports Injuries. Philadelphia, PA: Lippincott Williams & Wilkins; 2013.)
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Figure 41-35
ACCR technique.
 
AC ligament reconstruction and fascia repair. Right shoulder viewed from anterior. Integration of the graft at the AC capsule/ligament reconstruction. A: The long limb of the graft is taken lateral and posterior and used to augment posterior capsule repair. It is also incorporated into the trapezium fascia. The remnant is carried superior and used to augment the superior AC capsule repair. This is with nonabsorbable high-strength suture. B: Using “pants-over-vest” suture-repair technique, the deltoid–Trapezium fascia is repaired securely over the length of the clavicle. Note the repair is a critical part of the procedure and good tension and approximation of the fascia closure is vital. (With permission from Iannotti JP, Miniaci A, Williams G, Zuckerman DJ. Disorders of the Shoulder: Sports Injuries. Philadelphia, PA; Lippincott Williams & Wilkins; 2013.)
AC ligament reconstruction and fascia repair. Right shoulder viewed from anterior. Integration of the graft at the AC capsule/ligament reconstruction. A: The long limb of the graft is taken lateral and posterior and used to augment posterior capsule repair. It is also incorporated into the trapezium fascia. The remnant is carried superior and used to augment the superior AC capsule repair. This is with nonabsorbable high-strength suture. B: Using “pants-over-vest” suture-repair technique, the deltoid–Trapezium fascia is repaired securely over the length of the clavicle. Note the repair is a critical part of the procedure and good tension and approximation of the fascia closure is vital. (With permission from Iannotti JP, Miniaci A, Williams G, Zuckerman DJ. Disorders of the Shoulder: Sports Injuries. Philadelphia, PA; Lippincott Williams & Wilkins; 2013.)
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Figure 41-35
ACCR technique.
AC ligament reconstruction and fascia repair. Right shoulder viewed from anterior. Integration of the graft at the AC capsule/ligament reconstruction. A: The long limb of the graft is taken lateral and posterior and used to augment posterior capsule repair. It is also incorporated into the trapezium fascia. The remnant is carried superior and used to augment the superior AC capsule repair. This is with nonabsorbable high-strength suture. B: Using “pants-over-vest” suture-repair technique, the deltoid–Trapezium fascia is repaired securely over the length of the clavicle. Note the repair is a critical part of the procedure and good tension and approximation of the fascia closure is vital. (With permission from Iannotti JP, Miniaci A, Williams G, Zuckerman DJ. Disorders of the Shoulder: Sports Injuries. Philadelphia, PA; Lippincott Williams & Wilkins; 2013.)
AC ligament reconstruction and fascia repair. Right shoulder viewed from anterior. Integration of the graft at the AC capsule/ligament reconstruction. A: The long limb of the graft is taken lateral and posterior and used to augment posterior capsule repair. It is also incorporated into the trapezium fascia. The remnant is carried superior and used to augment the superior AC capsule repair. This is with nonabsorbable high-strength suture. B: Using “pants-over-vest” suture-repair technique, the deltoid–Trapezium fascia is repaired securely over the length of the clavicle. Note the repair is a critical part of the procedure and good tension and approximation of the fascia closure is vital. (With permission from Iannotti JP, Miniaci A, Williams G, Zuckerman DJ. Disorders of the Shoulder: Sports Injuries. Philadelphia, PA; Lippincott Williams & Wilkins; 2013.)
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Closure
 

The deltotrapezial fascia closure is an important step; the large fascia flaps are closed tightly with interrupted high-strength nonabsorbable sutures. Approximation of the attachments of the anterior deltoid fascia and the trapezius fascia are brought together with inverted interrupted stitches so that the knots are tied on the inferior side of the flap (Fig. 41-35), to minimize skin irritation. Occasionally, simple sutures are used to bury or tie down knots that appear prominent. The deep dermal layer is closed with buried 3.0 vicryl sutures, and a running subcuticular stitch is used for skin closure. In addition to intraoperative C-arm imaging to confirm reduction, final postoperative radiographs are taken to quantify AC joint reduction and bone tunnel position.

 
Postoperative Management for ACCR Technique
 

During the first 6 to 8 weeks, patients wear a prefabricated (Lerman Shoulder Brace, DJO inc. Vista, CA.) or abduction brace. It is most important that the postoperative brace provides a reduction support and protects the surgical repair against the pull of gravity. The brace may be removed for grooming and supine range of motion exercises only. After 8 weeks, the graft has obtained sufficient stability to begin upright range of motion exercises. At 12 weeks, if there is a pain-free normal range of motion, strengthening exercises are begun. These should target the scapular stabilizers that help retract the scapula and thereby decrease loads across the AC joint. Weight training may begin at 3 to 5 months postoperatively. Full contact athletics are allowed at 6 months but generally it requires 9 months to a year for patients to regain peak strength particularly with pressing activities, or lifting from the floor as in a dead lift.

 
Type III/V Variants
 

We treat all acute dislocations with an attempt at a nonoperative approach. They nearly always recover without incident, and rarely have any further sequelae. AC injuries associated with fractures of the coracoid process are treated nonoperatively in most cases. The fractures usually occur at the tip or the base of the coracoid. As long as the deltotrapezial fascia is not disrupted to a large extent, and there is no severe coracoid displacement, they are treated in the same manner as a type III injury. If the fracture of the coracoid extends intra-articularly into the glenoid, we consider surgical repair. This depends largely on the amount of intra-articular displacement. We use 5 mm or more of glenoid displacement as our criterion for surgical treatment. A CT scan is performed to evaluate this fracture as the glenoid fracture extension is readily appreciated with this study.

 
Potential Pitfalls and Preventative Measures
 

A thorough understanding of CC and AC anatomy is essential to the safe and effective treatment of AC joint injuries. Table 41-4 lists some of the surgical tips that may help assist the surgeon during reconstruction of the AC joint as well as help to stay away from some of the common pitfalls associated with this procedure.

 
 
Table 41-4
Surgical Pearls and Pitfalls
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Table 41-4
Surgical Pearls and Pitfalls
  •  
    While exposing the clavicle, create thick, intact deltotrapezial flaps to assist closure at the end of the case
  •  
    Clear the medial and lateral margins of the coracoid to assist passage of suture and graft under it
  •  
    Use a Satinsky vascular clamp to pass the shuttle suture under the coracoid from medial to lateral
  •  
    Keep an adequate bone bridge between the drill holes in the clavicle to reduce the risk of fracture
  •  
    Clear tissue from drill holes on the undersurface of the clavicle to ease passage of the graft
  •  
    Push up on the elbow to reduce the acromion to the clavicle before securing the repair
X
 

Indication for surgery is again one of the most difficult; we attempt to treat all patients nonoperatively. We allow for physical therapy to proceed for 4 weeks and then re-evaluate the patient. There are three studies that indicate early treatment (<6 weeks) leads to better return to sport (82 to 100%) compared to patients treated surgically but in a delayed (<6 weeks) fashion (77% to 78% return to sport).8 Pain and function loss are the reasons for reconstruction not cosmetic, as often the reconstruction will loosen and a residual deformity will persist after over reduction in the operating room.

 

One of the most common mistakes in the operating room is to not expose the AC joint, remove calcified tissue or scar within the CC space to allow for adequate reduction which is monitored and verified intraoperatively with fluoroscopy. Clavicle fracture is a real intraoperative complication and bone tunnels must be <5.5 mm, with enough bone between hole and posterior cortex to ensure no fracture secondary to stress raiser. Lastly, do not underestimate the importance of the deltotrapezial fascia closure with suture purchase in large flaps with over reduction of the fascia over the clavicle for added strength and blood supply.91

 

Postoperative brace wear and a very slow controlled therapy program will ensure optimal success. Wound complications can occur, so close monitoring in the first few weeks is important. A brace that elevates the forearm up toward the AC joint is important to protect the repair construct and compliancy with brace wear is one of the most significant hurdles in postoperative management.

Management of Expected Adverse Outcomes and Unexpected Complications in Acromioclavicular Joint Injuries

An inferiorly and medially directed force applied to the dorsum of the acromion most often results in injury to the AC articulation, the SC articulation, or the shaft of the clavicle. However, combined injuries have been reported. Wurtz et al.166 and Lancourt83 have reported combined AC dislocation and clavicle fracture. Several reports exist of simultaneous dislocations of both the SC and AC ends of the clavicle or “bipolar” dislocations.2,32,45,73,133 When this injury does occur, it is most often a posterior or type IV AC dislocation associated with an anterior SC dislocation. This underscores the importance of a thorough evaluation of any patient with an AC joint injury with particular attention being paid to the SC joint. 
Many complications may result from operative treatment of AC dislocations. Besides general complications such as wound infection and osteomyelitis that might develop from the operative procedure, several other specific complications may occur (e.g., a fracture through a drill hole, loss of purchase of the internal fixation, metal failure, and migration of the fixation device to other parts of the body). The incidence of loss of reduction is significant. The weight of the entire upper extremity is supported through a limited available area for fixation. In addition, the potential planes of motion at the injured AC joint are numerous and result in complex loading of the reconstruction. For these reasons, we advocate longer postoperative immobilization than is commonly described. 

Migration of Pins in Acromioclavicular Joint Injuries

Pins used to stabilize the AC joint have been reported to migrate into remote, life-threatening locations such as the lung, the spinal cord, the neck posterior to the carotid sheath, and the pleura or close to it.53,90 Vessels in the thorax and neck have also been penetrated by pin migration injury (more historical at this point). 
In most instances, pin migration can be prevented by bending a hook on the portion of the pin that protrudes from the acromion process. However, the pins can break, and then part of the pin is free to migrate. Patients must be prepared and forewarned of the possible necessity of pin removal and the complications of pins that are not removed. 
Lyons and Rockwood90 reviewed 37 reports of pin migration in operations about the shoulder, and recommended that pin use should be avoided in this area. When pins are utilized, they should be bent or have restraining devices to decrease the risk of migration. The patient should be informed of the risks. Close follow-up should be performed and the pins should be removed at the conclusion of therapy or whenever migration is noted. Pin migration may have devastating consequences, and there are reported deaths. (In general, pins should be avoided in this area.) 

Failure of Soft Tissue Repairs in Acromioclavicular Joint Injuries

In the treatment of a ligamentous injury to the AC joint, simple repair of the CC and AC ligaments without the additional support of CC sutures, screws, or internal fixation, will likely fail. This is particularly true in chronic injury of the AC joint as there is often significant displacement between the clavicle and the coracoid. Transfer of the acromial attachment of the coracoacromial ligament onto or into the medullary canal of the distal clavicle (the Weaver–Dunn technique) alone is not strong enough in general. It must be supplemented with additional fixation as recommended in the treatment section. 
Failure of soft tissue repairs can also result from suture breakage, suture anchor pullout, or screw breakage. If failure is noticed early in the postoperative period, reoperation to correct the problem is usually indicated. If failure occurs weeks to months after surgery, infection should be suspected and ruled out. 

Recently Reported Complications with ACCR Technique

Open treatment of highly displaced or chronic AC joint dislocations by reconstructing the CC ligaments with allograft tendons is gaining popularity in the literature, but complications are possible. This is highlighted by the recent report of three cases of clavicle fracture following AC joint reconstruction by Turman et al.156 In this report the incidence of clavicle fracture occurred in three of seven patients treated with CC ligament reconstruction: All patients had type V injuries, two patients had acute reconstructions (<6 month after injury), and one patient was treated 2 years after injury. The paper discusses clavicle bone tunnel diameter (all cases >5.5 mm) and the lack of AC joint ligament repair or reconstruction as a possible mode of failure. Increased anteriorposterior translation at the AC joint without AC ligament integrity has been demonstrated, this leads to increased forces on the native or reconstructed CC ligaments.40,52,99 As a second mode of possible catastrophic failure, bone tunnel widening has been reported167 and clavicle osseous anatomy and bone density relating to fracture risk for bone tunnel position and diameter. Our current recommendation to prevent this complication is to avoid >5.5 mm tunnels, minimize the graft, tap the clavicle tunnels before interference screw insertion and ensure at least 25 mm of bone between tunnels. 

Complications Related to Nonabsorbable Tape or Suture

CC fixation using grafts or synthetic material has been associated with various complications. Goldberg et al.61 described erosion of a Dacron graft through the distal clavicle in their series (Fig. 41-36). Moneim and Balduini104 noted a coracoid fracture after reconstruction of the CC ligaments through two drill holes in the distal clavicle. Fractures of the distal clavicle secondary to the use of loop sutures between the coracoid and the distal clavicle have been reported.94 Other complications include aseptic foreign body reactions and infections; Neault et al.110 reported three cases in which nonabsorbable tape or suture was directly related to a postoperative infection. Two infections occurred within a year, but one 5 years after repair of a type III injury. Colosimo et al.30 reported two cases of aseptic foreign body reactions to Dacron graft material 2 and 4 years after surgery. Microscopic examination revealed chronic inflammation with a foreign body giant cell reaction. Both patients improved after removal of the Dacron material and returned to work in 10 days. 
Figure 41-36
Complications from using cerclage material as a loop around the top of the clavicle and under the coracoid process for treatment of complete AC dislocations.
 
A: Preoperative radiograph demonstrating the type III dislocation of the AC joint. B: The postoperative radiograph demonstrates near-anatomic reduction using a 6-mm soft Dacron vascular graft loop. C: Gradual erosion of the Dacron graft completely through the distal clavicle can be seen. D: Note the superior migration of the shaft of the clavicle.
A: Preoperative radiograph demonstrating the type III dislocation of the AC joint. B: The postoperative radiograph demonstrates near-anatomic reduction using a 6-mm soft Dacron vascular graft loop. C: Gradual erosion of the Dacron graft completely through the distal clavicle can be seen. D: Note the superior migration of the shaft of the clavicle.
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Figure 41-36
Complications from using cerclage material as a loop around the top of the clavicle and under the coracoid process for treatment of complete AC dislocations.
A: Preoperative radiograph demonstrating the type III dislocation of the AC joint. B: The postoperative radiograph demonstrates near-anatomic reduction using a 6-mm soft Dacron vascular graft loop. C: Gradual erosion of the Dacron graft completely through the distal clavicle can be seen. D: Note the superior migration of the shaft of the clavicle.
A: Preoperative radiograph demonstrating the type III dislocation of the AC joint. B: The postoperative radiograph demonstrates near-anatomic reduction using a 6-mm soft Dacron vascular graft loop. C: Gradual erosion of the Dacron graft completely through the distal clavicle can be seen. D: Note the superior migration of the shaft of the clavicle.
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Acromioclavicular Arthritis

Symptomatic arthritis of the AC joint may occur after surgical fixation. Weaver and Dunn161 recommended distal clavicle excision and transfer of the coracoacromial ligament for both acute and chronic AC separations. In a review article, Cook and Heiner31 recommend distal clavicle excision as part of the acute surgical management of patients with AC separations. They reported that postoperative degenerative changes in the AC joint may occur in as many as 24% of patients following AC joint injury and that primary excision of the distal clavicle was associated with little morbidity. Conversely, the vast majority of series reporting the results of surgical management of AC separations do not advocate primary excision of the distal clavicle.8 Therefore, there is no consensus regarding primary distal clavicle excision and coracoacromial ligament transfer for acute AC injuries. It is our practice to preserve the AC joint articulation whenever possible. However, the scar formed within the dislocation space including the meniscus homologue needs to be removed to allow for reduction. If any distal clavicle is removed we attempt to remove it from the posterior edge of the clavicle as that is typically the location of abutment or impingement with the posterior edge of the acromion which may produce pain. 

The Role of Arthroscopy in the Treatment of Acromioclavicular Joint Injuries

The first report of arthroscopy for acute AC joint injuries by Wolf and Pennington164 described an all-arthroscopic technique of AC joint reconstruction. The coracoid was visualized through the subcoracoid recess in the anterior aspect of the joint. An anterior cruciate ligament guide is used to drill a hole through the clavicle and coracoid, and SecureStrand cable (Surgical Dynamics, Norwalk, CT) was used for fixation. They reported a series of four patients with no recurrence of deformity. Lafosse et al.82 published an all-arthroscopic technique for CC ligament reconstruction, which releases the coracoacromial ligament from the undersurface of the acromion and transfers it to the inferior clavicle. Proponents of arthroscopic reconstruction claim the benefits of this more minimally invasive technique include minimal violation of the deltotrapezial fascia, faster postoperative recovery, less pain, and fewer complications. 
Although many different arthroscopic techniques have been proposed, few clinical outcome studies have been published. Chernchujit et al.26 published a series of 13 patients who had an arthroscopic reconstruction following AC joint disruption using suture anchors and a titanium plate. These patients were followed for a mean of 18 months. Twelve patients returned to work without pain within 3 months of the operation and the average Constant Score at last follow-up was 95. Postoperative radiographs confirmed an anatomic reduction in 10 patients, residual subluxation in two patients, and redislocation of the joint in one patient. Given this, as well as evolving surgical techniques, an expanding role for arthroscopy in the management of these injuries may be seen in the future. 
Arthroscopic-assisted techniques to reconstruct the anatomic position of the CC ligaments have gained popularity in the last several years after initial reported successes.108,132,153 These techniques are being applied to reconstruction of type III and V AC joint dislocations acutely, and in chronic cases after failed conservative treatment. The use of suture-containing devices with cortical buttons is applied CC distance fixation, which if necessary can even be augmented with soft tissue graft and a separate AC joint capsule repair procedure, or when done very acutely (<1 week) allows for indirect reduction and scaring of the injured AC joint ligaments in a reduced position. These arthroscopic techniques allow for minimal soft tissue dissection, smaller incisions, and “safer” graft passage around the coracoid process as it is done under direct visualization. Comparing nonoperative to operative management of type III separations has not demonstrated significant improvement,143 but newer techniques may provide more stability while still allowing physiologic clavicle motion important for function. 
Saltzman et al. reported the latest progression in the refinement of this technique. They described the anatomic placement of two suture–button devices corresponding to the position of the ruptured trapezoid and conoid ligaments using two independent 3.5-mm clavicle and coracoid bone tunnels. Twenty-three patients were followed for an average of 30 months. The majority132 were reported to be Rockwood type V dislocations, and all procedures were done acutely (<10 days) with a comprehensive outcome with visual analog scale, Constant Score, SF-36 score, and repeat radiographs were performed. However, seven patients were lost to follow-up and they were not included, two failures, one infection needing removal of implant, four patients lost to follow-up. Certainly, the technique is innovative and may lead to shorter rehabilitation and better functional outcomes when compared to nonoperative management, but this remains uncertain. A prospective study with a nonoperative control group is required. This technique is not without complications, including increased CC distance, osteolysis around the suture–button device, and migration of implants. The VAS, Constant Scores improved significantly after surgery, however, similar to previous reports, the AC joint alignment was radiographically unsatisfactory in eight cases. A clear disadvantage of this technique is the superior clavicular displacement in over 30% of cases at 24 months postoperatively, and a high incidence of pain over the superior clavicle button. Despite some of the limitations of this paper the authors report good results but caution that this is an advanced arthroscopic technique and that tunnel and button placement are of utmost importance to avoid postoperative failures or loss of reduction. Scheibel et al.134 using an identical technique, published results on the arthroscopic stabilization of acute Rockwood type V AC dislocations in 28 of 37 consecutive patients available for final follow-up at an average of 26 months. Although there was a significant loss to follow-up they report good function, with ROM comparable to the uninjured side, no difference in strength, and maintenance of the CC distance reduction obtained intraoperatively. Complications included tenderness over the superior buttons in 11 patients (although none required removal). In addition, twenty-five patients (89%) demonstrated implant migration within the bone tunnels with mild osteolysis and enlargement of the tunnels. No significant loss of reduction was reported even with “stress” radiographs taken during evaluation. 
As noted in a few reports, the metallic button design tends to see more “motion” at the bone–button interface as the motion between the clavicle and scapula occurs with shoulder abduction.29,33,105,108,134 A recent study by Cohen et al.29 noted a decrease in pain, increase in CC distance, and metallic button migration into the clavicle with a larger “second-generation” button in which the diameter was increased from 6.5 mm to 10 mm. A second report by Motta et al.105 in which osteolysis and button migration was observed with 6-mm (first generation) prosthesis was eliminated in patients reconstructed with constructs containing 10-mm superior metallic buttons. Augmentation of a suture-suspension device with graft tissue provides increased initial stability and a load to failure that is similar to native CC ligaments. In a recently published technique, a suture–button device was utilized in part to facilitate this laboratory data.39 The superior, larger diameter, “low profile” washer can centrally accommodate a graft which gives the construct strength approaching the normal anatomy, while accommodating motion between the clavicle and scapula. This technique was applied to 10 patients with acute and chronic high-grade injuries with a short-term follow-up of 6 months with good to excellent results, and no reported complications (infection, hardware, or graft failure) encountered to date. The authors did not specifically address the AC joint, except in a few of the chronic cases in which a distal clavicle excision up to 5 mm was performed. Complications at the level of the coracoid fixation following arthroscopically assisted techniques have also recently been reported in conjunction with noncompliance or trauma.60 Gerhardt et al.60 reported a case of coracoid base fracture in an older but very athletic female patient who failed fixation secondary to fracture within 1 week following allograft tendon augmented CC fixation with a 6-mm suture–button construct. 

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