Chapter 49: Femoral Neck Fractures

John F. Keating

Chapter Outline

Introduction to Femoral Neck Fractures

Hip fractures are common and comprise 20% of the operative workload of an orthopedic trauma unit.265 Intracapsular femoral neck fractures account for 50% of all hip fractures. The lifetime risk of sustaining a hip fracture is high and lies within the range of 40% to 50% in women and 13% to 22% in men. Life expectancy is increasing worldwide, and these demographic changes can be expected to cause the number of hip fractures occurring worldwide to increase from 1.66 million in 1990 to 6.26 million in 2050.71 The estimated annual cost of treating these fractures is enormous and a significant burden to any health care system. 
There is very little debate about the management of the undisplaced intracapsular hip fracture, which is almost invariably treated with fixation. However, only 15% of these fractures are undisplaced. The remainder are displaced and occur predominantly in elderly female patients. Despite the ubiquitous nature of these fractures, there is still a surprising degree of variation in treatment. Options include reduction and fixation, unipolar arthroplasty, bipolar hemiarthroplasty, and total hip arthroplasty (THA). Any of the arthroplasty options may be cemented or uncemented. Recent surveys of practice indicate widespread variation in the use of these options.25,62,139,164 In recent years however, a number of randomized trials have been published, which have provided better evidence on which to base treatment choices. As a generalization these trials have suggested that for the majority of patients with a displaced fracture an arthroplasty is the best choice, and a modern design of arthroplasty is better that older designs of unipolar hemiarthroplasties. 

Epidemiology of Femoral Neck Fractures

Femoral neck fractures occur most frequently in elderly female patients. They are uncommon in patients younger than 60 years. There is some racial variation in the incidence. They are less common in black races270 and more common in black females than in males.234 Currently, these fractures are most common in the white populations of Europe and North America.150 The incidence increases exponentially with age.83 The risk of a second hip fracture within 2 years approaches 10% in women and 5% in men.22,48 In patients who sustain a second hip fracture, it is the same type of hip fracture in over 70%.102 
Epidemiologic studies have identified numerous risk factors associated with an increased risk of sustaining a hip fracture134 (Table 49-1). Nonmodifiable risk factors include increasing age, female sex, positive family history of osteoporotic fractures, and ethnic origin. Modifiable lifestyle risk factors increasing the risk of hip fractures include a low body mass index (<18.5), low sunlight exposure, low recreational activity, smoking, and alcohol abuse. Chronic disease in general tends to increase fracture risk. There is good evidence of increased hip fracture risk in association with diabetes mellitus (type 1 in particular), chronic renal disease, celiac disease, and primary hyperparathyroidism. Other conditions including depression, chronic liver disease, hypothyroidism, hyperthyroidism, and positive human immunodeficiency virus (HIV) status have also been linked to increased risk of hip fractures although the evidence is not as strong. Certain medications are associated with alteration of bone metabolism and increase fracture risk. Steroids are most commonly implicated, but other medications are also now well-recognized risk factors. These include antiepileptic medication, certain antidepressants (selective serotonin reuptake inhibitor), proton pump inhibitors, and HIV medications.66,144,148,247 
 
Table 49-1
Risk Factors for Hip Fractures
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Table 49-1
Risk Factors for Hip Fractures
Nonmodifiable
  •  
    Age
  •  
    Sex
  •  
    Ethnicity
  •  
    Reproductive factors
  •  
    Family history
Modifiable
  •  
    Weight
  •  
    Smoking
  •  
    Alcohol
  •  
    Level of physical activity
  •  
    Diet and nutritional status
Secondary Causes
  •  
    Comorbidities
    •  
      HIV
    •  
      Celiac disease
    •  
      Diabetes mellitus
    •  
      Previous fracture
    •  
      Primary hyperparathyroidism
    •  
      Anorexia nervosa
    •  
      Chronic liver disease
    •  
      Chronic kidney disease
    •  
      Spinal injury
    •  
      Depression
    •  
      Low body weight
    •  
      Immobility
    •  
      Neurologic disorders
    •  
      Multiple sclerosis
    •  
      Brain injury
  •  
    Medications
    •  
      Proton pump inhibitors
    •  
      Antipsychotic medications
    •  
      Aromatase inhibitors
    •  
      Oral corticosteroids
    •  
      Inhaled corticosteroids
    •  
      Gonadotrophin-releasing hormone inhibitors
    •  
      Long-acting progestogen-only contraceptives (Depo-Provera)
    •  
      Thiazolidinediones in type 2 diabetes
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In the past, it was predicted that the worldwide incidence of these fractures would increase until 2050. More recent epidemiologic studies from Europe have reported that the incidence of osteoporotic fractures may have leveled off48,234 and there is even evidence that the incidence may be reducing.149 One study has even predicted that the incidence and absolute numbers of hip fractures will fall.173 Whether these changes in the incidence are due to preventive measures or other therapeutic modalities is uncertain. 
Risk factors for hip fractures can be divided into those that increase the risk of falls in the elderly and those that predispose to changes in bone mass. The main risk factors linked to reduction in bone mass have already been given. Reduction in bone mass due to osteoporosis has an unequivocal link with the hip fracture and is present in over 84% of patients with femoral neck fractures. A reduction of bone mass at the hip of one standard deviation doubles the risk of hip fractures.64 Reduction in bone mass is due to osteoporosis in most patients. Other metabolic disorders of bone such as osteomalacia and renal osteodystrophy also render the femoral neck more susceptible to fracture, but they are much less prevalent.46 The risk of falling increases with age due to the increasing prevalence of risk factors for falling in older age groups. These include muscle weakness, abnormal gait or balance, neurologic disease, deteriorating eyesight, and medication with sedative or cardiovascular side effects.68,118 The direction of the fall is also important. Older patients who are fitter tend to fall forward and are more likely to sustain distal radial fractures or other upper limb fractures. Infirm elderly patients are more likely to fall sideways, and the force of the fall is sustained directly on the trochanteric region. 

Assessment of Femoral Neck Fractures

Mechanisms of Injury for Femoral Neck Fractures

The majority of these fractures occur in elderly female patients. The usual cause is a simple fall with force being transmitted to the femoral neck applied via the greater trochanter, resulting in the fracture.171 An alternative mechanism is external rotation of the leg, with increasing tension in the anterior capsule and iliofemoral ligaments. As the neck rotates, the head remains fixed and a fracture occurs. This mechanism would account for the posterior neck comminution observed in many of these fractures. The usual site of the fracture is in the weakest part of the femoral neck, located just below the articular surface. Quantitative computer tomography has confirmed site-specific bone loss within the femoral head and neck, with maximal bone loss in the more proximal and superolateral areas, which accounts for the site of fractures.59 
More rarely, the fracture is a result of higher energy trauma and these injuries are more common in younger patients where much greater force is required to cause the fracture.79 Head-on vehicle collisions may be responsible. The use of clipless pedals on bikes has become popular and these hamper the ability to quickly disengage the foot in the event of an accident, making a fall on the trochanter and a hip fracture more likely. In younger patients, the injury more frequently affects men. Finally, the femoral neck is a well-recognized site for stress fractures, and these occur as a result of repetitive cyclical loading, which eventually exceeds the strength of normal bone.98 

Associated Injuries with Femoral Neck Fractures

The vast majority of these fractures are isolated injuries. They are associated with distal radial fractures and proximal humeral fractures in elderly patients. Approximately 3% to 5% of these fractures occur in younger patients, and a proportion of these are a result of high-energy trauma and other fractures may be present. Ipsilateral femoral shaft and neck fractures are a well-recognized combination in these patients,205,260,289 and it is estimated that femoral neck fractures occur in 2% to 6% of femoral shaft fractures. 
Perhaps of more importance considering the population at risk is the concomitant presence of significant medical comorbidities. Data from prospective population studies indicate that 70% of patients with femoral neck fractures have an American Society of Anesthesiologists (ASA) grade of 3 or 4 at presentation, due to associated medical problems. Some of these are acute such as stroke or myocardial infarction and may be implicated in the cause of the fracture. 

Signs and Symptoms of Femoral Neck Fractures

Most patients will have a history of a simple, low-energy fall as the cause of injury. In 2% to 3% of cases, there is no history of trauma135 and the injury may be pathologic or a stress fracture. Stress fractures can occur in younger patients and are typically associated with heavy repetitive physical activity in males or the triad of anorexia nervosa, osteoporosis, and amenhorrea in female patients. The femoral neck is not a particularly common site of stress fractures and accounts for only 3% of these injuries.303 There is usually a history of prodromal symptoms in patients with stress fractures. 

History and Physical Examination

It has to be remembered in 25% to 30% of older patients there is cognitive impairment and there may be an unreliable history of the nature or timing of injury. In view of the significant rate of concomitant medical comorbidities, a careful history of previous medical problems is therefore important. An acute medical event or deterioration of a preexisting condition may have contributed to the fall causing the hip fracture, and this possibility should always be considered. Osteoporosis will be a feature of most patients with this injury, and treatment for this may be required in the postoperative period. Any other medical condition associated with osteoporosis may influence decision making and needs to be considered. In a significant proportion of younger patients with these fractures, there are medical comorbidities and risk factors, which predispose to the injury. These risk factors include alcohol abuse, steroids, renal failure, rheumatoid arthritis, and endocrine diseases—all of which are associated with decreased bone mineral density in younger patients. Some degree of renal impairment is common in the hip fracture population and has been identified with an increased risk of postoperative morbidity and mortality in two recent studies.19,168 
Physical findings may be limited in an undisplaced fracture. There may be no obvious deformity with the only finding a painful range of motion of the hip. In displaced femoral neck fractures, the affected leg is typically shortened and externally rotated. All motions of the hip are painful. Associated neurovascular injuries are exceptionally rare in the typical elderly patient but should be sought in younger patients with high-energy injuries. Physical findings do not differ significantly from extracapsular hip fractures and on clinical grounds the two hip fracture groups are indistinguishable. Anterior hip dislocation will also be associated with shortening and external rotation of the hip, but these are much rarer injuries and seldom occur in elderly patients. Patients with very limited mobility may have flexion contractures of the hip or knee if the patient is normally bed or wheelchair bound, and these may pose a problem, positioning the patient for surgery. Pressure sores should also be noted as these will increase the risk of wound infection and may impede postoperative mobilization depending on their location. 

Preoperative Traction

Application of skin traction to the injured limb was common practice in these patients. There were several theoretical reasons for doing so. It was considered that the relative immobilization of the limb would be helpful in reducing pain. The traction might also reduce the risk of further local soft tissue injury, help maintain a reduction, and increase the chance of a better reduction being achieved at the time of surgery in patients undergoing reduction and fixation. Several published trials5,94,142,199,217,242,243,253 have compared preoperative traction with no traction. No conclusive benefits have been shown for the use of traction in terms of pain relief, ease of fracture reduction, or quality of reduction achieved at the time of surgery, and it is therefore no longer recommended. 
As part of the routine preoperative work-up of these patients, some screening hematological investigations are routinely required. These include a full blood count, a blood group, and serum electrolyte estimation. Additional hematological or biochemical investigations might be appropriate depending on the associated medical problems. An electrocardiograph is also carried out in patients older than 60 years or in younger patients with any history of cardiac problems. However, there is little evidence that extensive preoperative investigation or cardiac status alters management. Ricci et al.244 carried out a retrospective study of 235 patients with hip fractures. A total of 35 (15%) underwent preoperative cardiac investigation. This did not alter perioperative management in any case but did result in a mean delay of 3 days to surgery in these patients. 

Imaging and Other Diagnostic Studies for Femoral Neck Fractures

Plain radiographs will identify the fracture in the majority of cases (Fig. 49-1). Anteroposterior (AP) and lateral radiographs are required. In the majority of cases, the diagnosis is clear on the AP radiograph. However, the degree of displacement can be difficult to discern in some patients and in others there may be doubt about the diagnosis. The lateral radiograph may be difficult to acquire due to pain but is useful in determining whether the fracture is present and whether it is displaced. Several recent studies have questioned the routine use of the lateral radiograph.3,56,72,187,197 However, they do concede that in equivocal cases the lateral radiograph can help determine whether the fracture is displaced. This is usually essential to determine the choice of treatment. If the lateral radiograph is not obtained routinely on admission then clinical decision making may be delayed in equivocal cases, while a lateral radiograph is obtained or further imaging is arranged. 
Figure 49-1
AP and lateral radiographs of a displaced femoral neck fracture.
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In 2% of cases, the fracture may be difficult or impossible to visualize on plain radiographs. In the past a technetium bone scan was often considered a useful investigation in this situation.90 Although it is usually positive in cases with a femoral neck fracture, there is the possibility of a false-negative in osteopenic bone if the investigation is carried out within 48 to 72 hours of the fall. It is also sensitive but not specific. CT scanning is a more accurate investigation but exposes the patient to further radiation. 
In cases where the diagnosis is doubtful, a magnetic resonance imaging (MRI) scan is probably the most useful additional form of imaging in modern practice (Fig. 49-2). It has been shown to be more accurate than a bone scan89,108,245 in the early stages after injury and there is no radiation.210 It will also demonstrate soft tissue problems that may be causing hip pain in the absence of a fracture. In a recent study, which compared CT scanning with MRI, there was no difference in the level of observer agreements about the presence of a fracture and the degree of displacement.56 An MRI scan is therefore the current additional imaging modality recommended where there is uncertainty about the presence of an intracapsular fracture. For the majority of patients, plain radiographs are adequate for clinical decision making. 
Figure 49-2
A 78-year-old patient presented with a painful left hip after a fall.
 
There is no fracture visible on the AP (A) or lateral (B) radiographs. A transverse MRI scan (C) shows a hemarthrosis of the left hip joint, and coronal plane MRI images show an undisplaced intracapsular hip fracture (D, E).
There is no fracture visible on the AP (A) or lateral (B) radiographs. A transverse MRI scan (C) shows a hemarthrosis of the left hip joint, and coronal plane MRI images show an undisplaced intracapsular hip fracture (D, E).
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Figure 49-2
A 78-year-old patient presented with a painful left hip after a fall.
There is no fracture visible on the AP (A) or lateral (B) radiographs. A transverse MRI scan (C) shows a hemarthrosis of the left hip joint, and coronal plane MRI images show an undisplaced intracapsular hip fracture (D, E).
There is no fracture visible on the AP (A) or lateral (B) radiographs. A transverse MRI scan (C) shows a hemarthrosis of the left hip joint, and coronal plane MRI images show an undisplaced intracapsular hip fracture (D, E).
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Some additional imaging is useful in the work-up of patients before surgery. In virtually all patients, a chest radiograph will be indicated since most patients are elderly and there is a high incidence of cardiorespiratory problems. Distal radial fractures and proximal humeral fractures are not unusual in these patients, and radiographs of these areas should be obtained if there is a clinical suspicion of a fracture in these locations. Even low-energy falls in older patients may be associated with intracranial trauma. If the onset of confusion coincides with the fall causing the hip fracture and there is evidence of cranial trauma, a CT scan is needed to rule out a remedial intracranial lesion. 
The association with osteoporosis has already been mentioned. The use of dual-energy x-ray absorptiometry (DEXA) scans is the accepted method of identifying patients at risk of osteoporotic fracture. However, in patients older than 70 years with a hip fracture, osteoporosis can be assumed to be present and these patients should be considered for prophylactic treatment. In patients under this age, osteoporosis cannot be assumed to be present and a DEXA scan should be obtained to confirm the presence or absence of osteoporosis to guide treatment. 

Classification of Femoral Neck Fractures

A number of classification systems have been devised for femoral neck fractures. Some authors have distinguished the fractures based on the anatomic location dividing intracapsular fractures into subcapital and transcervical types.17 However, the bone in the transcervical region is much stronger than that in the subcapital region, and it is doubtful whether many fractures actually occur in this region.13,157 Also, the exact location of the fracture is difficult to determine on the basis of plain radiographs.8,105,157 The majority of fractures undoubtedly occur in the subcapital region. In any event, the location of the intracapsular fracture has not been shown to influence management or outcome.240 The degree of displacement is the more important consideration, and this is the basis of the commonly used classification systems. 

Garden Classification

The Garden classification was described in 1961.104 It divides femoral neck fractures into four groups (Fig. 49-3). The divisions are based on the degree of displacement, which is judged on the AP radiograph by determining the relationship of the trabecular lines in the femoral head to those in the acetabulum. In the nonfractured hip, the trabecular lines in the femoral head are in the same orientation as those of the acetabulum. The Garden I fracture is a valgus-impacted subcapital fracture. The fracture is incomplete with a lateral fracture line that does not breach the medial cortex. The trabecular lines in the femoral head therefore form an angle with those in the acetabulum. In the Garden II fracture, the fracture is complete but undisplaced and the trabecular lines in the head are colinear with those in the acetabulum and the femoral neck distal to the fracture. Garden III subcapital fractures are incompletely displaced fractures. The femoral head has not lost contact with the femoral neck, but the head is varus and extended, resulting in angulation of the trabecular lines. The angulation is in the opposite direction to that described for Garden I fractures. Finally, the Garden IV fracture is completely displaced and the trabecular lines line up as the femoral head returns to a neutral position within the acetabulum. The femoral neck loses contact with the head and externally rotates, so the trabecular lines in the neck are not colinear with those in the head. 
Figure 49-3
The Garden classification of femoral neck fractures.
 
Type I fractures can be incomplete, but much more typically they are impacted into valgus, and retroversion (A). Type II fractures are complete, but undisplaced. These rare fractures have a break in the trabeculations, but no shift in alignment (B). Type III fractures have marked angulation, but usually minimal to no proximal translation of the shaft (C). In the Garden Type IV fracture, there is complete displacement between fragments and the shaft translates proximally (D). The head is free to realign itself within the acetabulum, and the primary compressive trabeculae of the head and acetabulum realign (white lines).
Type I fractures can be incomplete, but much more typically they are impacted into valgus, and retroversion (A). Type II fractures are complete, but undisplaced. These rare fractures have a break in the trabeculations, but no shift in alignment (B). Type III fractures have marked angulation, but usually minimal to no proximal translation of the shaft (C). In the Garden Type IV fracture, there is complete displacement between fragments and the shaft translates proximally (D). The head is free to realign itself within the acetabulum, and the primary compressive trabeculae of the head and acetabulum realign (white lines).
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Figure 49-3
The Garden classification of femoral neck fractures.
Type I fractures can be incomplete, but much more typically they are impacted into valgus, and retroversion (A). Type II fractures are complete, but undisplaced. These rare fractures have a break in the trabeculations, but no shift in alignment (B). Type III fractures have marked angulation, but usually minimal to no proximal translation of the shaft (C). In the Garden Type IV fracture, there is complete displacement between fragments and the shaft translates proximally (D). The head is free to realign itself within the acetabulum, and the primary compressive trabeculae of the head and acetabulum realign (white lines).
Type I fractures can be incomplete, but much more typically they are impacted into valgus, and retroversion (A). Type II fractures are complete, but undisplaced. These rare fractures have a break in the trabeculations, but no shift in alignment (B). Type III fractures have marked angulation, but usually minimal to no proximal translation of the shaft (C). In the Garden Type IV fracture, there is complete displacement between fragments and the shaft translates proximally (D). The head is free to realign itself within the acetabulum, and the primary compressive trabeculae of the head and acetabulum realign (white lines).
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The Garden classification has been widely used and is probably the most frequently utilized classification systems in the orthopedic literature pertaining to femoral neck fractures.318 Unfortunately, like many other orthopedic radiological classifications, inter- and intraobserver levels of agreement are not ideal. Frandsen et al.96 evaluated the classification and found that the level of interobserver agreement was only 22% across all four grades. Surgeons demonstrated high levels of agreement in determining whether fractures were undisplaced (Garden I or II) or displaced (Garden III or IV), but the level of agreement was much poorer when asked to subdivide cases across all four groups. Very similar findings were reported in a more recent similar study.296 
Another criticism of the classification is the small number of cases fulfilling the criteria for Garden II fractures. In a multicenter trial of 1,503 femoral neck fractures,15 only 19 (1.2%) were classified as Type II fractures and furthermore the outcome for undisplaced (Types I and II) fractures was independent of the grade assigned. Similarly, most displaced fractures (Types III and IV) are treated by arthroplasty, and the outcome is independent of the grade of displacement.84,160 
Beimers et al.18 suggested replacing the Garden classification with a two-part classification in which intracapsular fractures are categorized as “stable” or “unstable.” A stable fracture was defined as having some continuity across the fracture (impaction), and unstable fractures were defined as no continuity across the fracture site such that the two fragments would be expected to move independently with minimal force. In a study involving 34 fractures and 11 observers, the use of this system was compared with the Garden classification. They reported almost perfect inter and intraobserver agreement for their proposed system, and this was superior to the levels of agreement even when the Garden classification was used to group fractures into undisplaced (Types I and II) and displaced (Types III and IV). Adoption of this system would require corroboration of these observations in other larger studies. 

Pauwels Classification

The classification of Pauwels229 is based on the plane of the neck fracture (Fig. 49-4). He described three separate fracture types based on whether the fracture plane was vertical, oblique, or transverse. It was proposed that the classification would be predictive of fixation failure or nonunion with an increasing angle of fracture. The Type I fracture subtends an angle of 30 degrees or less. Type II fractures are between 30 and 50 degrees, and Type III fractures are greater than 50 degrees. This classification has been evaluated in a number of clinical studies and has not been shown to be reliable either in describing the fracture or in predicting the outcome.42,206,214,297 One limitation is that fractures with a vertical plane are actually rather rare and the majority of fractures are closer to transverse in orientation. It may be a more relevant classification for the younger patient.177 In these patients, the fracture is often sustained as a result of high-energy trauma and vertical fracture lines are more common. Liporace et al.172 recently described a series of Pauwels’ Type III fractures, and the mean age in their series was 42 years, which is considerably younger than the mean age for the general hip fracture population. The classification relates the prognosis to the angle of the fracture plane—as the angle increases the fracture instability increases and complications of fracture healing and fixation are more likely. However, the reliability of this classification has also been tested in a study evaluating interobserver levels of agreement.297 Ten surgeons were asked to classify 100 radiographs of intracapsular hip fractures using the Pauwels’ system. The level of agreement was only 0.31, which is poor. The authors recommended against using this classification method. 
Figure 49-4
The Pauwel classification of femoral neck fractures is based on the angle the fracture forms with the horizontal plane.
 
As the fracture progresses from Type I to Type III, the obliquity of the fracture line increases and, theoretically, the shear forces at the fracture site also increase.
As the fracture progresses from Type I to Type III, the obliquity of the fracture line increases and, theoretically, the shear forces at the fracture site also increase.
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Figure 49-4
The Pauwel classification of femoral neck fractures is based on the angle the fracture forms with the horizontal plane.
As the fracture progresses from Type I to Type III, the obliquity of the fracture line increases and, theoretically, the shear forces at the fracture site also increase.
As the fracture progresses from Type I to Type III, the obliquity of the fracture line increases and, theoretically, the shear forces at the fracture site also increase.
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AO/OTA Classification

The comprehensive classification of long bone fractures is an alphanumeric system based on the bone, the location of the fracture, and the fracture morphology. The femoral neck is designated 31B (Fig. 49-5). The B1 group describes undisplaced femoral neck fractures, the B2 transcervical fractures, and the B3 category describes displaced subcapital fractures. Although this system of classification provides a comprehensive method of classifying fractures in general, it has not proved to be popular for femoral neck fractures. It is a complex system of classification that limits its usefulness in routine clinical practice. Although it has been proposed to be a useful tool for research purposes, it has not stood up to scrutiny for this use. Blundell et al.32 found very poor levels of agreement with the subdivisions of the classification. Surgeons were able to divide the fractures into the main three groups: Undisplaced subcapital fractures, basal cervical fractures, and displaced subcapital fractures. Levels of agreement within subdivisions were very poor. Moreover, it was not found to be useful in selecting treatment nor was it predictive of outcome. It would seem therefore that this classification although theoretically attractive will prove impractical for use either in clinical practice or as a research tool. 
Figure 49-5
The OTA classification of femoral neck fractures.
 
The B1 group fracture contains nondisplaced to minimally displaced subcapital fractures. The B2 group includes transcervical fractures through the middle or base of the neck, and the B3 group includes all displaced nonimpacted subcapital fractures. Subgroups further specify fracture geometry. The diagrams represent common examples of the defined fracture pattern.
The B1 group fracture contains nondisplaced to minimally displaced subcapital fractures. The B2 group includes transcervical fractures through the middle or base of the neck, and the B3 group includes all displaced nonimpacted subcapital fractures. Subgroups further specify fracture geometry. The diagrams represent common examples of the defined fracture pattern.
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Figure 49-5
The OTA classification of femoral neck fractures.
The B1 group fracture contains nondisplaced to minimally displaced subcapital fractures. The B2 group includes transcervical fractures through the middle or base of the neck, and the B3 group includes all displaced nonimpacted subcapital fractures. Subgroups further specify fracture geometry. The diagrams represent common examples of the defined fracture pattern.
The B1 group fracture contains nondisplaced to minimally displaced subcapital fractures. The B2 group includes transcervical fractures through the middle or base of the neck, and the B3 group includes all displaced nonimpacted subcapital fractures. Subgroups further specify fracture geometry. The diagrams represent common examples of the defined fracture pattern.
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Other classifications18,45 based on judging the stability of the fracture have been proposed but have not been widely accepted. For the purposes of evaluating outcome, it is clear that surgeons are good at deciding whether the fracture location is intracapsular or extracapsular (basal cervical) and whether the fracture is displaced or undisplaced. These are also the key points in determining treatment and are predictive of the likely complications. At the present time, newer classifications have not been proven to be superior to these simple groupings. Older classifications are either of limited applicability in most patients (Pauwels)229 or in the case of Garden, still widely used but of limited reliability. Most clinical studies are concerned with undisplaced or displaced femoral neck fractures, and the subdivision of these two groups based on various classification systems is not a reliable guide to treatment or prognosis. 
Another classification occasionally used in patients with intracapsular hip fractures is the Singh index267 (Fig. 49-6), which is a method of estimating the degree of osteoporosis by fitting the pattern of proximal femoral trabecular lines into five separate categories. Two studies have evaluated the usefulness of this classification133,158 and found it unreliable. It shows poor levels of inter- and intraobserver levels of agreement. More importantly, it does not correlate with bone mineral density as measured by DEXA scans. It is of little practical value in modern orthopedic clinical practice. 
Figure 49-6
 
Singh’s index grades osteopenia from normal (grade 6; all trabecular groups are visible) to definite (grade 3; thinned trabeculae with a break in the principal tensile group) to severe (grade 1; only the primary compressive trabeculae are visible, and they are reduced) based on the ordered reduction in trochanteric, tensile, and ultimately primary compressive trabeculae. The grade is determined from a true AP projection of an intact proximal femur. (Adapted from Singh M, Nagrath AR, Maini PS. Changes in trabecular pattern of the upper end of the femur as an index of osteoporosis. J Bone Joint Surg. 1970;52A:457–467.)
Singh’s index grades osteopenia from normal (grade 6; all trabecular groups are visible) to definite (grade 3; thinned trabeculae with a break in the principal tensile group) to severe (grade 1; only the primary compressive trabeculae are visible, and they are reduced) based on the ordered reduction in trochanteric, tensile, and ultimately primary compressive trabeculae. The grade is determined from a true AP projection of an intact proximal femur. (Adapted from Singh M, Nagrath AR, Maini PS. Changes in trabecular pattern of the upper end of the femur as an index of osteoporosis. J Bone Joint Surg. 1970;52A:457–467.)
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Figure 49-6
Singh’s index grades osteopenia from normal (grade 6; all trabecular groups are visible) to definite (grade 3; thinned trabeculae with a break in the principal tensile group) to severe (grade 1; only the primary compressive trabeculae are visible, and they are reduced) based on the ordered reduction in trochanteric, tensile, and ultimately primary compressive trabeculae. The grade is determined from a true AP projection of an intact proximal femur. (Adapted from Singh M, Nagrath AR, Maini PS. Changes in trabecular pattern of the upper end of the femur as an index of osteoporosis. J Bone Joint Surg. 1970;52A:457–467.)
Singh’s index grades osteopenia from normal (grade 6; all trabecular groups are visible) to definite (grade 3; thinned trabeculae with a break in the principal tensile group) to severe (grade 1; only the primary compressive trabeculae are visible, and they are reduced) based on the ordered reduction in trochanteric, tensile, and ultimately primary compressive trabeculae. The grade is determined from a true AP projection of an intact proximal femur. (Adapted from Singh M, Nagrath AR, Maini PS. Changes in trabecular pattern of the upper end of the femur as an index of osteoporosis. J Bone Joint Surg. 1970;52A:457–467.)
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Outcome Measures for Femoral Neck Fractures

The majority of patients with intracapsular hip fractures are in an elderly age group, and the 70% will have significant medical comorbidities. Perhaps not surprisingly, the published literature has tended to focus on clinical outcomes measures of surgical intervention rather than detailed functional outcomes. Probably, the most commonly reported outcome is mortality.24,176 The surgery carried out is almost invariably fixation or some form of arthroplasty, both procedures with well-recognized clinical complications. Most studies on fixation have therefore provided outcome data on fixation failure, nonunion, and avascular necrosis (AVN). Arthroplasty complications include dislocation and infection, and these outcomes are reported in most published clinical studies. Consequently, reoperation to deal with complications is another important general clinical outcome measure, which is commonly reported. Some studies have incorporated survival analysis of implants to reflect this outcome.153,154 Other medical complications including thromboembolic events, respiratory infections, cardiac events, and other medical problems are reported in a more variable fashion. 

Functional Outcomes

Pain is an invariable feature after hip fracture surgery, and this is a commonly reported outcome, usually assessed by a simple visual analog scale or a more basic ordinal scale, rating pain from none to severe.218,224,241 Some assessment of mobility is a feature of many studies, but often this is reported in rather limited detail. This was often recorded just as ability to walk with or without aids, or level of mobility compared to prefracture status, as assessed by a questionnaire.10,250 Occasionally, more detail is provided with a scale rating mobility from complete independence without aids to bed bound.241,263 
In many prospective studies, there has been incorporation of a general health outcome measure. The more commonly used instruments have been the 12-item short form health survey (SF-12), SF-36, and the Euroqol disability questionnaire EQ-5D.11,30,131,153,154,179,285 These questionnaires are all validated for use in clinical studies. They do incorporate some assessment of physical function in the construction of the questions. The SF-12 and Euroqol have the advantage of being short and easily administered, which is an advantage for use in an elderly population. 
Simpler measures of general activity such as the Katz activities of daily living score have also been used.28,30,285 This rates ability to carry out activities of daily living on a seven-point scale. A similar score assessing activities of daily living is the Barthel index,100 which is a 10-item scale with a score from 0 (total dependence) to 100 (complete independence). A similar measure in this category is the Timed Up and Go test,179,286 a combined measure of mobility and balance. The score is based on the amount of time in seconds required to get up from a chair, walk 10 ft (3.05 m) in an open environment, return to the chair, and sit. Depending on the time taken, patients are divided into four categories that reflect mobility levels. 
There are a number of hip-specific outcome scores in common use. However, the majority have been developed as a measure of hip function in the osteoarthritic patient. The most familiar are probably the Harris hip score28,100,179,241,294 and the Oxford hip score12 although the Charnley score30,218,285 and the Johanson hip score153,154 have also been used. These outcome measures have been validated in studies of patients with osteoarthritis, and it is probably a reasonable to infer that they can be used for hip fracture patients with reliability. However, since in general they are designed for use with a younger and generally biologic fitter group of patients, they may lack sensitivity as an outcome measure in the hip fracture population. 
Economic analysis has been incorporated in some studies.138,153,154 These studies have usually estimated the cost-effectiveness of the surgical options based on a calculation of the total hospital costs associated with a particular surgical treatment type. 

Pathoanatomy and Applied Anatomy Relating to Femoral Neck Fractures

Surgical Anatomy of Femoral Neck Fractures

Skeletal Anatomy

The hip is a large synovial ball and socket joint. In the case of the femoral neck, the relationship to the femur and hip joint is characterized by anteversion of the femoral neck in the transverse plane and the femoral neck shaft angle in the coronal plane. The femoral neck subtends an angle with the femoral shaft of between 130 and 135 degrees in the normal hip. An angle less than this is referred to as coxa vara, and an increased angle is termed coxa valga. Femoral neck anteversion describes the angle subtended by the femoral neck to the transcondylar axis, which is usually between 15 and 25 degrees. A recent study of femoral neck length and anteversion in extracapsular and intracapsular hip fracture patients found no correlation between these parameters and the type of fracture sustained.101 
In addition to these two angles, hip axis length and femoral neck width have been shown to have an influence on the risk of femoral neck fracture. The hip axis length is the distance from the lateral aspect of the trochanteric region along the axis of the femoral neck to the inner table of the pelvis (Fig. 49-7). An increase in hip axis length and femoral neck width and lower neck shaft angles are associated with an increased risk of femoral neck fracture.38 Hip axis lengths are known to be longer in white females than in Asian and black populations, which may partly explain the increased susceptibility to femoral neck fracture in this group.65 
Figure 49-7
Hip axis length and neck shaft angle (α).
 
A longer hip axis length is associated with a greater lever arm and greater force being applied to the femoral neck during a fall. A lower neck shaft angle is seen in coxa vara and will also increase the risk of femoral neck fractures for the same reason.
A longer hip axis length is associated with a greater lever arm and greater force being applied to the femoral neck during a fall. A lower neck shaft angle is seen in coxa vara and will also increase the risk of femoral neck fractures for the same reason.
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Figure 49-7
Hip axis length and neck shaft angle (α).
A longer hip axis length is associated with a greater lever arm and greater force being applied to the femoral neck during a fall. A lower neck shaft angle is seen in coxa vara and will also increase the risk of femoral neck fractures for the same reason.
A longer hip axis length is associated with a greater lever arm and greater force being applied to the femoral neck during a fall. A lower neck shaft angle is seen in coxa vara and will also increase the risk of femoral neck fractures for the same reason.
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The femoral neck angle and anteversion have to be taken into consideration when reduction and fixation is selected as a method of treatment. Increased femoral anteversion may be present and occasionally coxa varus or valgus, which will influence implant placement. The internal trabecular system of the femoral head was described by Ward.306 The trabeculae are orientated along lines of stress and the thickest come from the calcar region and radiate into the lower part of the femoral head. The calcar femorale is a dense vertical plate of bone extending from the posteromedial portion of the femoral shaft under the lesser trochanter, radiating to the greater trochanter and reinforcing the posteroinferior portion of the femoral neck.117,129 The presence or absence of trabecular lines forms the basis of the classification of osteoporosis described by Singh. 

Blood Supply

The blood supply of the hip joint is of particular relevance when considering intracapsular hip fractures (Fig. 49-8). The anatomy has been well described.61,62 There are three sources: Capsular vessels, intramedullary vessels, and a contribution from the ligamentum teres. In the adult the most important source of femoral head blood supply is derived from the capsular vessels. These vessels arise from the medial and lateral circumflex femoral arteries, which are in turn branches of the profunda femoris in 79% of cases. In 20% of patients, one or other of these vessels arises from the femoral artery, and in 1% both vessels arise from the femoral artery.301 The medial and lateral femoral circumflex arteries form an extracapsular circular anastomosis at the base of the femoral neck, and the ascending cervical capsular vessels arise from this. They penetrate the anterior capsule at the base of the neck at the level of the intertrochanteric line. On the posterior aspect of the neck, they pass beneath the orbicular fibers of the capsule to run up the neck under the synovial reflection to reach the articular surface. Within the capsule these are referred to as retinacular vessels. There are four main groups (anterior, medial, lateral, and posterior) of which the lateral group is the largest contributor to femoral head blood supply. The most important retinacular vessels arise from the deep branch of the medial femoral circumflex artery.60,146,258,290 These vessels supply the main weight-bearing area of the femoral head. The contributions of the lateral femoral circumflex artery and metaphyseal vessels are much less important by comparison.137,146,258,290,291 At the junction of the articular surface of the head with the femoral neck, there is a second ring anastomosis termed the subsynovial intra-articular ring.52 The terminal branches of the deep branch of the medial femoral circumflex artery penetrate the femoral head 2 to 4 mm proximal to the articular surface on its posterosuperior aspect.109 
Figure 49-8
Vascular anatomy of the femoral head and neck.
 
Anterior aspect (top). Posterior aspect (bottom). LFC, lateral femoral circumflex artery.
Anterior aspect (top). Posterior aspect (bottom). LFC, lateral femoral circumflex artery.
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Figure 49-8
Vascular anatomy of the femoral head and neck.
Anterior aspect (top). Posterior aspect (bottom). LFC, lateral femoral circumflex artery.
Anterior aspect (top). Posterior aspect (bottom). LFC, lateral femoral circumflex artery.
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These capsular vessels are vulnerable to damage in displaced subcapital fractures.43,44,161 They enter the femoral head just below the articular margin. Displacement of the femoral head due to a fracture in this area will damage these vessels, jeopardizing the blood supply to the femoral head and resulting in the risk of AVN if the head is retained.106 Claffey53 has shown that the risk of AVN is greatly increased if the important lateral retinacular vessels are damaged. 
The artery of the ligamentum teres is a branch of the obturator or medial femoral circumflex artery.61 Some additional blood supply in the adult reaches the head via the medullary bone in the neck. Clearly, the latter vessels will be as vulnerable to disruption in any displaced fractures as the retinacular vessels. Although the vessels entering the head through ligamentum teres vessels contribute to femoral head blood supply, their contribution is generally not sufficient to maintain complete vascularity of the entire head.137 After a displaced fracture, revascularization of the femoral head occurs by revascularization from areas of the head with retained blood supply and ingrowth of vessels from the metaphysis.43,44,53 
The portion of the femoral neck within the hip joint capsule has no cambial layer in its fibrous covering to participate in callus formation during fracture healing. Fracture union depends on endosteal healing alone, which is one of the reasons why prolonged union times are common with these fractures. 

Ligaments

The hip joint capsule extends down to the intertrochanteric line over the anterior aspect of the femoral neck, but posteriorly the lateral half of the femoral neck is extracapsular. Three important condensations of the hip joint capsule are considered ligamentous stabilizers of the hip. The ischiofemoral ligament controls internal rotation in flexion and extension. The lateral arm of the iliofemoral ligament has dual control of external rotation in flexion and both internal and external rotation in extension. The pubofemoral ligament controls external rotation in extension, with contributions from the medial and lateral arms of the iliofemoral ligament.183 Increased tension in the iliofemoral ligament is considered to have a role in causation of femoral neck fractures and production of the posterior neck comminution characteristic of the injury. 

Sensory Supply

The hip joint derives sensation from the obturator, femoral, sciatic, and superior gluteal nerves. The anteromedial part of the joint is supplied by the obturator nerve. The anterior capsule receives sensory innervation from the femoral nerve. The posterior aspect of the joint is supplied by the sciatic nerve, and there is a contribution to the posterolateral capsule from the superior gluteal nerve. This has some relevance for pain control after hip fracture. Femoral nerve blockade is commonly used, but this will produce incomplete pain relief. Much of the pain relief derived from this block is secondary to the reduction in muscle spasm achieved. 

Muscles

Hip flexion is produced by the iliopsoas, which inserts on the lesser trochanter. When the femoral neck is intact, contraction of this muscle also produces internal rotation. In femoral neck fractures, the muscle pull will result in external rotation of the femoral shaft. External rotation of the hip is also caused by the action of the piriformis, the gemelli, and the obturator internus. Abduction is produced by the gluteal muscles, which are supplied by the superior gluteal nerve. Damage to this nerve may occur in the direct lateral approach to the hip, particularly the inferior division. This may contribute to development of a Trendelenburg gait after arthroplasty for fractures. 
Adduction of the hip is produced by the muscles in the adductor compartment, which are supplied by the obturator nerve. These include adductor longus, adductor magnus, and adductor brevis. These muscles are not of particular importance in femoral neck fractures but may contribute to the shortening of the leg characteristic of a displaced intracapsular fracture. 

Common Surgical Approaches

Anterior Approach (Smith–Petersen).
The Smith–Petersen approach is the standard anterior approach to the hip. It is created by making an incision along the iliac crest and extending in a longitudinal and inferior direction from the anterior superior iliac spine. The gluteal muscles are detached from the external wing of the ileum, and then a plane is developed between the tensor fascia lata and the sartorius. This will allow access to the anterior aspect of the hip joint. The reflected head of the rectus femoris is detached to gain direct access to the capsule. This surgical approach is useful for fixation of femoral head fractures but is not routinely used in the management of femoral neck fractures. 
Anterolateral Exposures (Watson-Jones).
This ap-proach is an anterolateral exposure of the hip that gains access to the hip joint via an intermuscular plane. A lateral incision is made in line with the femur that extends up to the iliac crest. It angulates in a posterior direction to finish 8 to 10 cm anterior to the posterior superior iliac spine. The fascia is divided in line with the incision. A plane is developed between the anterior edge of the gluteal muscles and tensor fascia lata that allows access to the anterior capsule of the hip joint. This approach has most commonly been used in femoral neck fractures when open reduction is necessary. It can be used for hemiarthroplasty or total hip replacement (THR), but access is limited and in particular it is not ideal for femoral stem placement. The lateral or posterior exposures are preferable for arthroplasty. 
Direct Lateral Approach (Hardinge).
This approach is popular for arthroplasty of the hip following a displaced intracapsular fracture. There is a higher rate of dislocation with THA following hip fracture than with total arthroplasty performed for primary osteoarthritis of the hip.24,176,241 The direct lateral exposure is associated with a lower rate of dislocation after arthroplasty than the posterior approach, and it is preferable for hip fracture patients if THA is being carried out. Variations on this approach have been described by a number of authors. In general, the patient is positioned in the lateral position and a longitudinal incision is made centered on the greater trochanter. Following division of the fascia, the trochanteric bursa is excised. An incision can then be made through the tendons of the gluteus medius extending distally to reflect the vastus lateralis off the femur. At the proximal end of the trochanter, the gluteal muscles are split in line with their fibers. Care should be taken not to carry this split too proximal, or injury to the superior gluteal nerve is a risk. This risk is increased if dissection is performed more than 5 cm proximal to the trochanter. The approach can then be developed by carrying dissection down on to bone reflecting the tissues in an anterior direction until the capsule is incised around the base of the neck. The alternative is to divide the gluteus medius and minimus tendons separately exposing the hip joint capsule, which is incised separately. The hip can then be exposed by flexion and external rotation of the femur, which delivers the fractured femoral neck out of the joint, allowing access to the fractured head in the acetabulum. Once this is removed, hemiarthroplasty or total arthroplasty can be carried out. 
Posterior Approach to the Hip.
The posterior exposure of the hip may be performed with the patient in the prone or lateral position. The former position is popular for acetabular fracture surgery, but for arthroplasty the lateral position is preferable to facilitate correct component position. The approach is made with an incision centered on the greater trochanter extending distally down the shaft and proximally extending toward the posterior superior iliac spine. The more proximal extent of the approach, which provides access to the sciatic notch and the posterior column of the acetabulum, is not routinely required for femoral neck surgery. The fascia is divided in line with the incision. Above the level of the trochanter, the gluteus maximus fibers are split. More distally the exposure is facilitated by partial division of the gluteus maximus insertion into the linea aspera. The sciatic nerve should be identified and protected. The short external rotators of the hip are then divided, starting proximally with piriformis. The obturator internus and the gemelli are then divided and reflected posteriorly where they lie over the sciatic nerve. The capsule can then be incised to expose the femoral head and neck. The neck is accessed by flexing the knee to 90 degrees and internally rotating the femur. 
This approach provides excellent access to the hip joint for hemi or total arthroplasty. It also has the advantage of being extensile proximally and distally, although this facility is not often required during femoral neck fracture surgery. The main disadvantage is the higher rate of dislocation than the anterior or anterolateral exposures. Although the risk is acceptably low in osteoarthritic patients, the risk is much higher in patients undergoing total arthroplasty for femoral neck fracture, and this is a significant drawback of utilizing the approach for this procedure in this group. 
Other Approaches.
There are other approaches to the hip joint including the medial exposure and the Charnley transtrochanteric exposure, but these have no place in femoral neck fracture surgery. Trochanteric osteotomy is best avoided, particularly in elderly patients, due to frequent problems with reattachment. 

Femoral Neck Fracture Treatment Options

Fractures of the femoral neck are displaced in 85% of cases at presentation, and 97% of patients are older than 60 years. The clinical decision-making process in most cases therefore concerns the optimum choice of treatment for these patients. Although undisplaced fractures are only 15% of the total, they are encountered frequently because of the common nature of femoral neck fractures. 

Nonoperative Treatment of Undisplaced Femoral Neck Fractures

Nonoperative treatment is an option in undisplaced femoral neck fractures, and some authors have recommended this method of treatment and reported good results.237 Patients can be mobilized touch weight-bearing with crutches, and the fracture can be expected to heal in 4 to 6 weeks. The advantage of this method is that it avoids surgery, but most studies show that there is a significant risk of displacement during nonoperative treatment. 

Outcomes

The risk of displacement varies from 19% to 46%57,261,302 in reported studies. Two comparative studies63,126 compared nonoperative with operative treatment of undisplaced femoral neck fractures. In a small study comprising 23 patients, Hansen126 reported better results in operatively treated cases. Nonunion or displacement complicated 10 of 16 cases treated nonoperatively compared with no complications in the operative group of seven patients. 
In a larger study, Cserháti et al.63 compared the outcome of 122 nonoperative cases and 125 operative cases. Operatively treated patients had much better outcomes. The duration of hospitalization was a week shorter, full weight-bearing began 11 days earlier, and there were no early displacements in the operative group compared with 20% in the nonoperative group. In a smaller, noncomparative study, Parker and Pryor220 reported nonunion in twice as many patients treated nonoperatively compared with operatively treated patients. Conn and Parker57 reported failure in 19% of nonoperatively treated patients at 1 year, but two more recent studies reported secondary displacement in over 40% of cases.261,302 The mean time to displacement was 23 days in one of these studies,302 but displacement occurred up to 24 weeks after injury in some patients. 
There are therefore only very limited indications for nonoperative treatment of these fractures. It can be considered in patients with a poor chance of survival due to medical comorbidities or malignancy and in the occasional patient who declines nonoperative treatment.132 Occasionally, patients present late after the injury in which case nonoperative treatment is also an option. 

Operative Treatment of Undisplaced Femoral Neck Fractures

Fixation of Undisplaced Intracapsular Femoral Neck Fractures

In the majority of patients, fixation is the treatment of choice for the undisplaced intracapsular hip fracture. There are a large number of implants available to choose from. In modern orthopedic practice, the usual choice is either a cannulated screw system (Fig. 49-9) or a sliding hip screw device with a short plate. These have superseded older devices such as hook pins,278 Knowles pins,275 and the Watson-Jones nail,231 even though these implants were documented as having results comparable to more modern implants. 
Figure 49-9
(A) AP and (B) lateral view of displaced intracapsular hip fractures well-healed 9 months after fixation with three cannulated screws.
Rockwood-ch049-image009.png
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Surgical Procedure

Positioning.
Fixation of undisplaced femoral neck fractures is usually straightforward. The patient is placed supine on the operating table, with a fluoroscope positioned to screen an AP and lateral radiograph of the hip. This is facilitated by flexion and abduction of the contralateral hip. 
Technique.
The surgical exposure required is minimal, and the procedure can be carried out percutaneously. If the procedure is performed open, a short linear incision is made from just inferior to the vastus lateralis ridge of the greater trochanter for approximately 5 cm. Guide wires can then be introduced into the femoral neck using the image intensifier to guide the position. Most surgeons using a cannulated screw system prefer to use three screws, but there is some evidence that two screws may be as effective.159 The optimum position of the screws has also been a source of debate, particularly whether they should be parallel or divergent. Once again, convincing evidence to suggest that screw position greatly influences outcome is lacking. Perhaps surprisingly, a recent study showed more favorable outcomes if screws were used with washers rather than alone.318 
A number of studies have compared sliding hip screw devices with cannulated screw implants for these fractures. Two meta-analyses have addressed the issue of implant selection,213,224 analyzing over 25 trials comparing implants. The conclusion of these meta-analyses was that there was no clear evidence of superiority of any one implant for fixation of these fractures. Cannulated screw systems do have the advantage of a less invasive surgical exposure with less blood loss and pain166 and are the most popular choice. 
Outcomes.
Following surgery, patients can be mobilized weight-bearing as tolerated. Serial radiographs are taken to document union, which can be expected to occur in more than 90% of cases. The rate of nonunion in most series is low, but it does occur and overall a rate of 7% can be expected. Although these are undisplaced fractures, there is a definite rate of late AVN, which varies from 4% to 22%47,49,57,201,222 (Table 49-2). Younger patients should be reviewed for longer periods to detect this, but long-term follow-up may be impractical in older patients. The functional outcome of undisplaced femoral neck fractures reflects the low complication rate and is generally good. The majority of patients return to their prefracture level of mobility and residence.286 
Table 49-2
Results of Studies Investigating Internal Fixation of Undisplaced Femoral Neck Fractures
Authors No. of Patients Nonunion Avascular Necrosis
Chiu and Lo49 250 6% 7.2%
Phillips and Christie231 72 5.6% 22.5%
Stappaerts and Broos275 33 3% 6.1%
Strömqvist et al.278 85 3% 1.6%
Conn and Parker57 375 6.4% 4.0%
Chen et al.47 37 5% 10.8%
Bjørgul and Reikerås27 225 9% 4.4%
Total 1,077 6.4% 5.8%
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Arthroplasty for Undisplaced Femoral Neck Fractures

Since there is a definite rate of reoperation for nonunion and AVN after fixation, there may be reasons to consider some form of arthroplasty for the undisplaced fracture. In theory, arthroplasty would avoid the main complications of internal fixation and thus reduce the rate of reoperation. Parker et al.225 addressed this issue in a study where 346 patients with undisplaced neck fractures treated by internal fixation were compared with 346 patients with displaced fractures treated by hemiarthroplasty. The patients were matched for age, sex, residential status, and ASA grade. Patients treated with hemiarthroplasty had a significantly longer surgical procedure, a longer hospital stay, a higher rate of perioperative complications, and a higher 1-year mortality (26% vs. 19% for fixation). The fixation group had better mobility and less pain at 1 year. The reoperation rate was higher in the fixation group (43/346 vs. 14/346). The authors concluded that fixation was the treatment of choice for undisplaced fractures. 
The results of this study must be interpreted with caution since they are based on the assumption that the patient who sustains an undisplaced fracture is similar to the patient with a displaced fracture, which may not be the case even allowing for the matching that was part of the study design. Arthroplasty may be worth considering in selected cases of undisplaced fractures such as in the presence of preexisting symptomatic osteoarthritis of the hip. Arthroplasty should also be considered in patients with medical comorbidities likely to be associated with a significant risk of failure after fixation (e.g., chronic renal failure, rheumatoid arthritis, and corticosteroid treatment). 

Operative Treatment of Displaced Femoral Neck Fractures

These form the majority of patients with femoral neck fractures. In contrast to undisplaced fractures, where there is general agreement regarding treatment, there is considerable variation in surgical practice in the treatment of displaced femoral neck fractures. Three recent surveys of European and North American orthopedic surgeons evaluated how surgeons opted to treat displaced fractures.25,62,139 The results showed that most surgeons believed reduction and fixation was the treatment of choice for displaced fractures in patients younger than 60 years. Almost all surgeons preferred arthroplasty in patients older than 80 years. There was much more variation in patients between the age of 60 and 80 years, with surgeons using reduction and fixation, unipolar hemiarthroplasty, bipolar hemiarthroplasty, and THR to differing extents. In the past few years, a number of randomized trials have evaluated these treatment options and have provided better clinical evidence on which to base clinical decisions regarding the optimum procedure. 

Reduction and Fixation of Displaced Femoral Neck Fractures

Reduction and fixation of displaced femoral neck fractures is a less popular treatment than formerly. The main reason for this is the high failure rate with this procedure due to fixation failure, nonunion, and AVN. It is still widely used however, and is the treatment of choice in most younger patients. 

Surgical Procedure

Positioning.
The surgical technique is identical to that described for undisplaced femoral neck fractures once the fracture is reduced. The usual method of reduction is to apply gentle traction and internal rotation to the leg. This is a key point since a common error is to apply excessive traction with forceful rotation to the leg. This may result in a valgus reduction that is very difficult to correct by closed means. The correct technique is therefore to place the patient on the traction table, with minimal traction and rotation in the first instance. Radiographs can then be taken to verify the position of the fracture. If the fracture is incompletely reduced then small incremental increases in both traction and internal rotation checking the position after each adjustment can be carried out until the reduction is judged adequate. 
Technique.
Reduction should be judged on the AP and lateral view. The junction of the convex femoral head and neck should produce an S-shaped curve in all planes175 (Fig. 49-10). A perfect reduction may not be possible if there is comminution of the femoral neck, which is not unusual. On the AP view, a valgus reduction is preferable to a varus reduction. A valgus reduction is inherently more stable, whereas a varus reduction is associated with a much higher risk of fixation failure.14 What constitutes an acceptable reduction is debatable, but a 20-degree varus reduction is associated with a 55% risk of failure, and Arnold6 recommended less than 20 degrees of posterior angulation to minimize the same complication. In relation to the reduction, the risk of AVN has been shown to be lowest with anatomic reduction. Either varus or valgus reductions increase the risk.50 
Figure 49-10
Lowell demonstrated that the cortices of an anatomically aligned femoral head and neck will project shallow S- or reverse S-shaped curves on both x-ray views (A).
 
Malalignment is demonstrated by a flattening of one curve and a sharp apex on the opposite side (B). These findings are usually easier to appreciate intraoperatively with fluoroscopy than are the primary compressive trabecular alignments needed to measure an alignment index.
Malalignment is demonstrated by a flattening of one curve and a sharp apex on the opposite side (B). These findings are usually easier to appreciate intraoperatively with fluoroscopy than are the primary compressive trabecular alignments needed to measure an alignment index.
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Figure 49-10
Lowell demonstrated that the cortices of an anatomically aligned femoral head and neck will project shallow S- or reverse S-shaped curves on both x-ray views (A).
Malalignment is demonstrated by a flattening of one curve and a sharp apex on the opposite side (B). These findings are usually easier to appreciate intraoperatively with fluoroscopy than are the primary compressive trabecular alignments needed to measure an alignment index.
Malalignment is demonstrated by a flattening of one curve and a sharp apex on the opposite side (B). These findings are usually easier to appreciate intraoperatively with fluoroscopy than are the primary compressive trabecular alignments needed to measure an alignment index.
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Garden106 described an alignment index to measure the quality of reduction (Fig. 49-11). This is based on measurement of bony trabecular alignment on the postoperative AP and lateral radiographs. On the AP view, the angle subtended by the central axis of the medial trabecular system in the head and the medial cortex should normally be 160 degrees. On the lateral view, the central trabecular axis in the head is in line with the femoral neck, an angle of 180 degrees. Garden91 reported good results when the angle was between 155 and 180 degrees on either view. When outside this range, the risk of fixation failure and AVN increased. Failure to achieve a stable reduction is most commonly due to posterior comminution of the femoral neck.13,105,106,257 This is not under control of the surgeon and if an acceptable reduction cannot be achieved then consideration should be given to undertaking an arthroplasty, although open reduction should be considered in younger patients where arthroplasty is undesirable. 
Figure 49-11
The Garden alignment index.
 
An angle of 160 to 180 degrees on both AP and lateral images was considered acceptable by Garden. Anatomic (black) and unacceptable (blue) reductions are shown.
An angle of 160 to 180 degrees on both AP and lateral images was considered acceptable by Garden. Anatomic (black) and unacceptable (blue) reductions are shown.
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Figure 49-11
The Garden alignment index.
An angle of 160 to 180 degrees on both AP and lateral images was considered acceptable by Garden. Anatomic (black) and unacceptable (blue) reductions are shown.
An angle of 160 to 180 degrees on both AP and lateral images was considered acceptable by Garden. Anatomic (black) and unacceptable (blue) reductions are shown.
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When the fracture is reduced, fixation can be achieved with either cannulated screws or a sliding hip screw and short side plate. Although two screws may be adequate for undisplaced fractures, three cannulated screws are a safer choice for a displaced fracture27,159 and are the most common implants used. 
Most surgeons use a parallel pin placement and a triangular configuration, although evidence for the superiority of one particular pin configuration is lacking. 
Postoperative Care.
Postoperatively, patients can be mobilized using touch weight-bearing for 6 weeks, but older patients are frequently unable to cooperate with instructions to remain non-weight-bearing, so for the majority of patients this is impractical. In any event, the forces experienced in the hip joint are greater with complete non-weight-bearing than with touch weight-bearing, so the latter policy is more logical. A Cochrane review125 analyzed the published literature for mobilization strategies after hip fractures. One trial published over 40 years ago evaluated weight-bearing allowed at 2 weeks compared with 12 weeks after fixation of displaced intracapsular hip fractures. There were no differences in complications or functional outcomes. Other studies evaluated various postoperative physiotherapy regimens after fracture fixation, but results were inconclusive. The authors of the review concluded that there was insufficient evidence to support the effectiveness of the various mobilization strategies evaluated in the published studies. 
Outcomes.
Femoral neck fracture union is often slow and usually takes longer than 6 months in the majority of cases. Barnes et al.15 reported union in only 14.5% of patients with displaced fractures at 6 months. Patients require regular radiographs until this time to ensure the fracture is uniting uneventfully. AVN tends to manifest itself after fracture union and is most common in the second year after injury.15 Younger patients should be followed up for 2 years, with radiographs on a 6-monthly basis, to detect this complication. 
The results of reduction and fixation of displaced femoral neck fractures are considerably inferior to the results reported for undisplaced fractures treated by fixation. There is a high incidence of postoperative complications (Table 49-3). These are mainly due to fixation failure, nonunion, and AVN. Although AVN is a well-recognized complication, the majority of reoperations are performed for early fixation failure in osteoporotic bone and nonunion.176 
Table 49-3
Results of Studies Investigating Reduction and Internal Fixation of Displaced Femoral Neck Fractures
Authors No. of Patients Nonunion Avascular Necrosis Fixation Failure
Bjørgul and Reikerås27 241 19.5% 3.7% 5%
Parker et al.222 568 30.1% Not recorded Not recorded
Stappaerts and Broos275 85 31.8% 32.7% Not recorded
Strömqvist et al.278 215 25.6% 9.2%
Tidermark et al.286 66 27.3% 9.1% Not recorded
Asnis and Wanek-Sgaglione9 91 6.56% 19.8% 5.4%
Total 1,266 25.5% 10.9%
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In a Cochrane review of the literature, Parker and urusamy216 identified 17 trials comparing fixation with arthroplasty for displaced intracapsular hip fractures.31,69,141,143,145,154,198,218,236,249,250,268,272,281,285,295,299 The analysis of the data in these trials indicated that there were some significant perioperative differences. In particular, the length of surgery, blood loss, requirement for transfusion, and deep infection were all higher in the arthroplasty group. Arthroplasty had a lower rate of reoperation than fixation. The duration of hospital stay, mortality, and return to previous residential status showed no differences. Less pain and better function were reported with arthroplasty although the data were not entirely conclusive. 
Several larger randomized trials have been published since 200012,28,153,154,218,241,250,285,294 comparing reduction and fixation to various types of arthroplasty for displaced fractures (Tables 49-4 to 49-6). The results have been remarkably uniform—reduction and fixation compared unfavorably to arthroplasty in terms of reoperation rates and functional outcomes. The reoperation rates for reduction and fixation in these trials have been notably higher than in previously published studies and vary from 39% to 50%. One study published a longer term 10-year follow-up of the original patient cohort of 450 patients randomized to fixation or arthroplasty (a mixture of hemiarthroplasty and total arthroplasty).167 The overall mortality was high at 75%, but there was no difference between the two groups. The failure rate in the fixation group was 45.6% compared with 8.8% in the arthroplasty group. The functional outcome was poorer in the fixation group even in those patients who had a healed fracture. 
 
Table 49-4
Rates of Dislocation in Eight Randomized Trials
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Table 49-4
Rates of Dislocation in Eight Randomized Trials
Authors Total No. of Patients Fixation Hemiarthroplasty THR
Ravikumar and Marsh241 271 0 13.2% 20.2%
Rogmark et al.250 450 0 10.4%
Parker et al.218 455 0 0
Tidermark et al.285 110 0 N/A 2%
Keating et al.154 298 4.2% 3% 4.3%
Frihagen et al.100 222 5.4% 1.1% N/A
Blomfeldt et al.29 120 N/A 0% 0
Baker et al.12 81 N/A 0 7.5%
Total 5% 2.5% 7.9%
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Table 49-5
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Table 49-5
Rates of Revision Surgery in Eight Randomized Trialsa
Authors Total No. of Patients Fixation Hemiarthroplasty THR
Ravikumar and Marsh241 271 33% 24.2% 6.7%
Rogmark et al.250 450 48.8% 10.4%
Parker et al.218 455 39.8% 5.2% N/A
Tidermark et al.285 110 41.5% N/A 4.1%
Keating et al.154 298 39.0% 5.4% 8.7%
Frihagen et al.100 222 50% 14.5% N/A
Blomfeldt et al.29 120 N/A 0 3.3%
Baker et al.12 81 14.6% 2.5%
Total 41.2% 9.6% 5.4%
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Table 49-6
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Table 49-6
Mortality Rates at 1 Yeara
Authors Total No. of Patients Fixation Hemiarthroplasty THR
Ravikumar and Marsh241 290 25.3% 27.5% 22.5%
Rogmark et al.250 450 12.4% 14.5%
Parker et al.218 455 27.0% 27.5%
Tidermark et al.285 110 18.9% N/A 10.2%
Keating et al.154 298 15.2% 16.2% 8.7%
Frihagen et al.100 222 21.4% 26.4% N/A
Blomfeldt et al.29 120 5.0% 6.7%
Baker et al.12 81 17.1% 7.5%
Total 20.0% 23.1% 12.4%
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Several studies have evaluated factors contributing to the high failure rate of this surgical technique. The level of the fracture in the femoral neck has not been shown to make any difference as long as the fracture is intracapsular.240 As already indicated, there is no clear evidence that one particular implant has any advantage over another.213,224 The quality of reduction does have an influence on the failure rate. In particular, a varus reduction has been estimated51 to increase the risk of failure fourfold. 
More recently, the use of locking plate technology has been reported to improve the results of femoral neck fractures. The Targon FN implant comprises a side plate with six locking screw ports. Two screws are inserted distally to fix the plate to the lateral cortex. The surgeon then has the option of inserting up to four screws into the femoral neck. These screws have an internal sliding mechanism that allows some impaction at the fracture side but no lateral migration into soft tissues. Parker and Stedtfeldt223 reported on 83 patients with displaced and undisplaced fractures treated with this device. The rate of nonunion was 3% in undisplaced fractures and 15% in displaced fractures. AVN complicated 1 of the 37 undisplaced fractures and 3 of the 46 displaced fractures. These results are encouraging, but a more recent study21 reporting the use of a proximal femoral locking plate reported much poorer results. In a small series of 18 patients, early failure was reported in 7 of the 18 (37%) cases. This was clearly a much smaller series, but more data from comparative studies are required to determine whether these locking implants have any advantage over existing fixation devices and arthroplasty. 

Ancillary Techniques

A number of modifications to the technical aspects of reduction and fixation have been suggested in an effort to improve the results. These have included treatment of the hemarthrosis, addition of compression at the fracture site, open reduction, timing of surgery, and use of various cements to improve fixation. 
Femoral neck fractures are associated with a hemarthrosis, and this is known to increase the intracapsular pressure in the hip.35,77,79,184,190 On this basis it has been suggested that ancillary measures such as aspiration of the hip joint capsule or open reduction might be useful in order to decompress the hemarthrosis and improve the quality of reduction. Clinical studies have failed to show evidence that aspiration or capsulotomy to drain the hemarthrosis is actually of any benefit. 
A number of studies have assessed the value of open reduction and compression of femoral neck fractures, but there is no convincing evidence that either technique enhances results.212 The use of compression across the fracture using a sliding hip screw has been compared with no compression in one study.95 No benefit was conferred by compression of the fracture, but the risk of nonunion was significantly greater with compression (32.9% in the compression group vs. 18.3% in the noncompression group). 
Open reduction of femoral neck fractures has been compared with closed reduction in two studies.114,292 Both trials were relatively small (49 patients114 and 92 patients).292 Operating time was longer for the open reduction group, but there was no significant difference in the quality of fracture reduction between the open and closed groups. This was reflected in the outcome, with no significant differences noted in the mean time to union, or the rates of nonunion and AVN. Larger, better-designed trials are necessary to determine whether open reduction confers any advantage. Based on current evidence, open reduction should therefore be reserved mainly for young patients with higher energy trauma where an adequate closed reduction cannot be achieved and arthroplasty is not a desirable option. 
Timing of reduction and fixation after injury might also be reasonably expected to have an influence on the outcome. Experimental studies indicate that cellular changes in the femoral head are seen by 6 hours after fracture, but osteocyte cell death occurs quite slowly and may not be complete until 2 to 3 weeks after the fracture occurs.43,44 If fixation is indicated, it may therefore be carried out in patients who present late. Barnes et al.15 found that the timing of surgery had no influence on the rates of AVN and nonunion in patients treated with reduction and fixation up to 7 days after injury. In contrast to this finding, Jain et al.140 compared early fixation (within 12 hours of injury) with delayed fixation (more than 12 hours) and recorded an incidence of AVN in 16% of the delayed group compared with none in the early fixation group. 
Several studies have investigated the possibility of improving the outcome by enhancing fixation with the use of cement. Mattsson and Larsson185,186 reported on the use of calcium phosphate cement in a randomized trial comparing an augmented group with a group treated with standard internal fixation. The augmented group had better early stability but had an increased requirement for later reoperation due to nonunion and AVN, and there was no definite advantage demonstrated with the use of cement. The literature on this topic has been the subject of a review170 that concluded that although there was experimental evidence to show cement improved the stability of fracture fixation there was no evidence from clinical studies that the complication rate and requirement for reoperation were reduced. 
Outcome studies indicate that fractures that heal without complication are usually associated with acceptable functional results. In patients who develop complications the results are not satisfactory, and there is a high rate of revision surgery to deal with the complications.286 In the majority of cases, the revision surgery is needed to deal with fixation failure and nonunion rather than AVN. In patients with healed fractures, the result is sometimes not satisfactory. Femoral neck shortening following fixation can occur in up to a third of patients in the absence of any healing complication.316 This adversely affects hip abductor muscle function, which may contribute to poor results in these cases. 

Secondary Arthroplasty

Patients who are treated with reduction and fixation may be converted to a hemiarthroplasty or THR to treat failure of fixation. However, the evidence suggests that secondary THR in this situation is associated with a higher rate of complications than THA carried out as a primary procedure. McKinley and Robinson188 compared secondary THA with an age- and sex-matched cohort who had received THA as a primary procedure for displaced subcapital hip fractures. They recorded a significantly higher rate of infection, dislocation, and loosening in the group who had the procedure carried out as revision for failed fixation. Other studies evaluating secondary THA without a comparison group have concluded that results were acceptable but the rates of common complications in most series are above those reported for primary THA.26,97,202,203,307 The present evidence therefore indicates that if THA is used, superior results can be expected in patients where the procedure is the primary operation. Similar findings have been reported for hemiarthroplasty. Superior results with lower complication rates were found when comparing a cohort of 282 primary hemiarthroplasties with 149 secondary hemiarthroplasties for failed screw fixation. The reoperation rate was 5% in the primary hemiarthroplasty patients and 11% in the secondary hemiarthroplasty patients, a difference that was statistically significant.99 

Hemiarthroplasty

Unipolar Hemiarthroplasty.
Unipolar hemiarthroplasty has been widely used for femoral neck fractures. Although modern prostheses are available, a surprising number of cases are still carried out using older, unsophisticated implants such as the Austin Moore and Thompson hemiarthroplasty (Figs. 49-12 and 49-13). Although the use of these older implants is gradually declining, a recently published randomized trial comparing a cemented Thompson with a cemented Exeter hemiarthroplasty noted no differences at 1 year, although the Thompson stem was associated with more technical problems at the time of surgery.211 
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Figure 49-12
An Austin Moore prosthesis.
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Figure 49-13
A Thompson prosthesis.
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The procedure has a number of advantages for this fracture. Surgery is technically relatively straightforward, and it eliminates the risks of nonunion and fixation failure, which contribute to the high rate of revision surgery associated with reduction and fixation. 
Technique.
The procedure is usually carried out with the patient in the lateral position. Most surgeons choose a posterior or a direct lateral exposure. Lateral exposures may result in some abductor weakness, but there is a lower risk of dislocation.153 Once the hip joint is exposed, the femoral neck is delivered into the wound and the femoral neck is cut. The femoral head can then be removed from the acetabulum. The femoral canal is reamed and the chosen prosthesis inserted. Although older implants such as the uncemented Austin Moore are cheap and easy to use, they are not ideal implants in fitter patients. The lack of modularity means that it is necessary to judge the leg length and hip soft tissue tension correctly at the time of insertion, with no ability to vary this after insertion. Proximal femoral fractures can occur at the time of insertion. This complication can be minimized by completely excising the hard residual femoral neck bone laterally at the base of the greater trochanter. This will allow the prosthesis to press into softer cancellous bone in the lateral region, avoiding excess pressure on the calcar causing fracture. Once the implant is inserted, reduction is accomplished. Forceful maneuvers, especially rotation, should be avoided to minimize the risk of a periprosthetic femoral shaft fracture. Once the implant is reduced, the capsule is repaired and the wound closed. 
Results.
Unipolar hemiarthroplasty avoids the risks of fixation failure, nonunion, and AVN associated with reduction and fixation, but does expose the patient to the risks of arthroplasty. However, due to the large head diameter, the risk of dislocation is low (2% to 3%) and wound infection rates should be of the order of 1% to 2% (Table 49-7). Uncemented implants have been associated with an increased risk in proximal femoral fractures at the time of insertion, and the incidence of this has been reported in up to 12% of patients.308 Cemented stems have also been associated with better functional outcomes, with less thigh pain.91,215,266 Long-term survival of these implants has been good, mainly because of the limited life expectancy of the patients who sustain femoral neck fractures. In one long-term study, the survival rate was 94% at 5 years and 83% at 12 years.204 This has to be interpreted in light of the high mortality of these patients—81% died within the study period. Most patients with these implants may never survive to develop the longer term complications of stem loosening or acetabular protrusion. Most authors would now agree that the use of these older uncemented designs should be confined to patients with very limited mobility and functional demands. 
Table 49-7
Results of Studies Investigating the Use of Unipolar Hemiarthroplasty in the Treatment of Displaced Femoral Neck Fractures
Authors Reference No. of Implants Revision Dislocation Protrusion Infection Excellent/Good
Kwok and Cruess163a 139 599 Nr 5.3% Nr Nr 64%
Cornell et al.58b 50 15 0 6.7% 0 Nr Nr
Wachtl et al.304c 263 162 3.1% 1.2% 1.8% 0.6% Nr
Raia et al.239d 202 60 3.3% 1.7% 0 1.7% 74%
Singh and Deshmukh266e 229 54 5.5% 7.4% 0 1.9% 74%
Norrish et al.204f 171 500 4.6% 2.0% 1.8% 0.8% 81%
Total 1,390 4.2% 3.6% 1.3% 0.9% 67.7%
 

Nr, results not recorded.

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Bipolar Hemiarthroplasty.
The use of bipolar hemiarthroplasty has been a very popular alternative to the unipolar hemiarthroplasty. There is a wide range of modern bipolar cemented and uncemented stems available (Figs. 49-14 and 49-15). Bipolar heads have a number of proposed advantages. There is an articulation between the inner head and the shell and the shell and the acetabulum. This dual articulation was proposed to reduce the risk of wear and acetabular protrusion. Some studies have suggested that, at least with some designs, the articulation ceases to function as it was intended and for practical purposes the implant behaves as a unipolar implant in a proportion of patients.80,135,232 There is also some evidence that the function of the articulation varies with the diameter of the inner head. Brueton et al.40 investigated motion with two bipolar designs, one with a 22-mm inner head and the other with a 32-mm inner head. The prosthesis with the smaller head diameter exhibited predominantly intraprosthetic motion compared with the larger diameter head where motion was mainly extraprosthetic. The authors recommended selection of a bipolar design with a smaller diameter inner head on the basis of these findings. 
Figure 49-14
AP view of cemented Exeter bipolar hemiarthroplasty.
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Figure 49-15
An uncemented modular arthroplasty in good position.
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Technique.
The implant is available in cemented and uncemented designs. The surgical approaches and techniques are identical to those as described for unipolar hemiarthroplasty. Modern bipolar hemiarthroplasties have a modular design with a variety of inner head neck lengths. Trial heads and neck additions are available with some implants. This makes precision in judging tissue tension and leg length easier at the time of surgery. If a cemented stem is used, modern cementing techniques with a medullary plug and cement pressurization should be used. 
Results.
The results of bipolar hemiarthroplasty for femoral neck fractures have generally been good (Table 49-8). The complication rates are higher than those reported for hip arthroplasty in osteoarthritis but still acceptably low. Dislocation and infection rates are usually 3% or lower. The early mortality in this group of patients tends to be high, but one study of prosthetic survival found that the 10-year survivorship was 93.6%, which is comparable to the outcome following THA for osteoarthritis.122 Revision for acetabular protrusion is uncommon, which is reported in less than 2% of cases. The functional outcome is seldom reported in much detail. Most authors use relatively crude measures of outcome although the Harris hip score has been used in a number of studies reporting good to excellent results in 65% to 90% of patients (Table 49-8). 
Table 49-8
Results of Studies Investigating the Use of Bipolar Hemiarthroplasty in the Treatment of Displaced Femoral Neck Fractures
Authors No. of Implants Revision Dislocation Protrusion Infection Function (Pain Free)
Bezwada et al.23a 256 4.8% Nr 3.5% 0 69%
Eiskjaer and Ostgård82b 268 1.9% 3.0% 0 Nr Nr
Moshein et al.195c 87 4.6% 2.3% 2.3% 1.1% 88%
Wetherell and Hinves309d 561 3.6% 2.9% 5.6% 1.1% 95%
Overgaard et al.209e 171 4.1% 2.3% 0 0.6% 94%
Haidukewych et al.122 212 4.7% 1.9% 0.5% 1.4% 95%
Total 1,555 3.7% 2.6% 1.5% 0.9% 86%
 

Nr, results not provided in the published text.

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Perhaps not surprisingly, studies comparing unipolar with bipolar hemiarthroplasty have failed to show any advantage for the bipolar design. Eight studies have compared the outcome of unipolar and bipolar hemiarthroplasty.41,58,69,181,207,239,254,298 Most of these compared a cemented unipolar implant with a cemented bipolar implant, but three compared an Austin Moore implant with a bipolar implant.181,239,298 There was no difference in the reported rates of dislocation, deep infection, reoperation rates, or other general complications such as deep venous thrombosis. Levels of mobility also showed no significant differences. 
The rate of dislocation may be similar,228 but the implications are different. In the case of a unipolar hemiarthroplasty, a closed reduction is usually possible. The same does not apply for a bipolar hemiarthroplasty. The bipolar head is mobile, and the rotation possibly mitigates against a successful closed reduction. Attempts at closed reduction can result in dissociation of the two articulating components.238 In most cases of dislocation therefore, an open reduction of the bipolar prosthesis is required. 
The use of cement has also been evaluated in a number of clinical studies37,74,85,127,256,271 and summarized in two recent meta-analyses.11,212 Most of these studies have involved the use of older implants such as the Austin Moore and Thompson prostheses. Uncemented implants were found to be significantly faster to perform, but the perioperative complication rates were no different. Function tended to be better with cemented stems. Most studies reported better mobility and less pain in patients with a cemented implant. Studies involving more modern uncemented implants have found no differences.256 Two recently published randomized trials70,93 compared a cemented hemiarthroplasty with a modern hydroxyapatite-coated implant. Functional outcomes at 3 and 12 months as measured by the Harris hip score, the Barthel index, and EQ-5D were no different in Figved’s trial. Deangelis et al.70 found no clinically or statistically significant differences in the need for assistance with ambulation, Older Americans Resources and Services Activities of Daily Living subscales, or the Energy/Fatigue Scale at 30-day, 60-day, and 1-year reviews. Complications and mortality rates were evenly distributed between the two implant groups. The results suggest that modern uncemented implants have results equivalent to cemented stems. 

Total Hip Replacement

THR has not been a popular treatment choice for displaced intracapsular hip fractures in the past. THR is the most complex operative treatment option for a displaced femoral neck fracture. It is a longer operation than the other operations, and depending on the implant used, may be the most expensive operative procedure. However, it is worth noting that some modern bipolar implants are more costly than many conventional THRs. 
Many patients who sustain this injury are not natural choices for THA—most are elderly, with limited mobility, and 25% to 30% have some degree of cognitive impairment. In addition to these considerations, the initial experience with THA for intracapsular fractures was not very encouraging—high rates of loosening and dislocation were features in some early repo-rts.115,116,283 This led to pessimism about the use of THA, and most surgeons are still reluctant to consider it as a treatment option.25 However, there is now an accumulating body of evidence that supports the use of THA in suitable patients, and some recent trials have indicated that the functional outcome may be more favorable than other procedures. 
Indications.
Most recent studies31,153,154,250,285 have recommended THA for independently mobile patients with no cognitive impairment (Fig. 49-16). Some medical conditions, notably chronic renal failure147 and rheumatoid arthritis,7,130,276 have been associated with a high rate of failure following reduction and fixation. THA should be considered particularly in rheumatoid arthritis where there may be involvement of the acetabulum in the disease and there are high rates of failure.276,279 Displaced subcapital fractures are very rare in osteoarthritic patients, but for the same reason should be treated in fit patients with a total arthroplasty. 
Figure 49-16
A cemented Exeter total hip arthroplasty for a femoral neck fracture in a fit, older patient.
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The age of the patient must also be taken into consideration. Most surgeons still regard reduction and fixation as the treatment of choice in patients younger than 60 years.25 Reduction and fixation of these injuries in younger patients is normally successful.108 However, a proportion of these patients are medically unwell with conditions including steroid treatment, alcoholism, and other conditions associated with osteoporosis that predispose to a higher risk of failure and nonunion. THA is probably a better choice in these cases. In displaced subcapital fractures in patients younger than 50 years, the incidence of nonunion and AVN in one study was 37%,123 although not all patients with AVN required conversion to arthroplasty. 
Technique.
The operation is carried out with either a lateral or posterior surgical approach to the hip, as described above for hemiarthroplasty. Some aspects of the procedure differ from THA in the osteoarthritic hip. The acetabular anatomy is not distorted by osteophytes, and the bone is osteoporotic rather than sclerotic as in osteoarthritis. Particular care is therefore required in preparation of the acetabulum. Overreaming can easily occur with excessive removal of bone from the anterior and posterior walls or the acetabular floor. Cautious reaming is therefore necessary with regular visual evaluation of the amount of bone removed. Capsulotomy and sometimes excision of the hip capsule is performed in the osteoarthritic hip to facilitate exposure and hip mobility. This is not required in hip fractures, and the capsule should be conserved to allow repair at the end of the procedure. Cementing of the socket can be carried out using standard techniques. In uncemented sockets, the desire for a tight impaction fit must be balanced against the risk of pelvic fracture if the chosen implant diameter is too large for the osteoporotic bone to accommodate it without a stress fracture. Finally, any malposition of the acetabular component must be avoided to minimize the risk of postoperative dislocation. The femoral stem preparation and insertion are carried out as described for hemiarthroplasty. The choice of the femoral head may differ from THA for arthritis—many surgeons would choose a slightly larger head diameter (30 to 32 mm) for hip fracture patients to reduce the risk of dislocation. Following reduction a careful capsular repair can be accomplished with the same aim. 
Results.
THA is a more complex procedure than hemiarthroplasty or fixation, and one possible concern is a higher mortality rate. However, the 30-day mortality in a series of over 7,000 patients undergoing THA for a hip fracture was 2.4%,226 which compares favorably to the mortality rate with other procedures. Data from the Norwegian hip registry169 suggested that there is a slight increase in standard mortality ratio compared with the non-THA population (standardized mortality ratio = 1.11). Randomized trials have not shown a higher mortality with THA compared with other treatment options.30,153,154,241,250,285 It would seem therefore that mortality is more influenced by increasing age and medical comorbidities rather than by the magnitude of the surgical procedure. 
Most studies of THA for femoral neck fractures have relatively short follow-up periods, often for only 2 years. Three studies have carried out longer term review and calculated 10- and 20-year survival of THA after femoral neck fractures. These studies indicate that 10-year survival of THA is in excess of 90%. Tarasevicius et al.284 reported 10-year survival rates of over 90% for stems and cups in THA in a series of 135 patients. The implant used had no influence on the outcome. Mabry et al.178 reported 93% 10-year survival and 76% 20-year survival of Charnley cemented implants used to treat femoral neck nonunion. Age less than 65 years and obesity were associated with an increased risk of loosening. Lee et al.165 reported survival rates of 95% at 5 years, 94% at 10 years, 89% at 15 years, and 84% at 20 years for cemented THA used as a primary treatment for intracapsular hip fractures. These survival rates are slightly less favorable than for THA carried out for primary osteoarthritis but are nevertheless still excellent long-term results. 

Summary of Randomized Studies Evaluating Treatment Modalities for Displaced Femoral Neck Fractures

Hemiarthroplasty Versus Internal Fixation

This question has been addressed in three studies. There were important differences between the studies. Parker and Pryor.219,221 randomized 455 patients with displaced femoral neck fractures to hemiarthroplasty (uncemented Austin Moore prosthesis) or internal fixation (three cannulated screws). Fixation had a significantly shorter operation time with less blood loss. The deep infection rate was higher in the hemiarthroplasty group (6/163 vs. 0). Reoperation was required in 12/163 (7.4%) of the hemiarthroplasty group and 77 (34.5%) of the fixation group. Pain and mobility was no different. A long-term follow-up of this trial at 9 to 15 years showed no change in the outcomes from the original study although it should be noted that 93% of the participants had died at that stage. Blomfeldt et al.29 randomized 60 patients with severe cognitive impairment to fixation or uncemented Austin Moore hemiarthroplasty. The fixation group had a higher reoperation rate (33% vs. 13%), but the difference was not significant with the trial numbers. The functional outcome was no different. 
Frihagen et al.100 compared fixation with cemented bipolar hemiarthroplasty in 222 patients. The complication rate was 15% in the hemiarthroplasty group and 50% in the fixation group. The functional outcome as measured by the Harris hip score, EQ-5D, and Barthel index was significantly better in the hemiarthroplasty group at all time points. They concluded that hemiarthroplasty was a better choice. 
Of the three trials, that published by Frihagen et al.99 is more relevant to modern practice—it was a relatively large trial with a modern cemented bipolar hemiarthroplasty. The other trials used an Austin Moore prosthesis, which is inferior to modern arthroplasty designs, and the trial by Blomfeldt et al.29 was underpowered. 

THR Versus Internal Fixation

One trial has compared these two options, with an initial report in 2003285 and a longer term follow-up in 2005.28 Patients were randomized to have a cemented THA or fixation with two cannulated screws. All patients were independently mobile with no cognitive impairment. At the time of the 4-year follow-up, the mortality rate was 25% in both groups. The reoperation rate was 4% in the THA group and 47% in the fixation group, a highly significant statistical difference. Hip function was significantly better in the arthroplasty group, with less pain and better mobility. The quality of life measured by the EQ-5D was better in the arthroplasty patients. 

THR Versus Hemiarthroplasty

Several large randomized trials have been published recently comparing THA with other modalities of treatment28,30,153,154,241,250,285 (Tables 49-4 to 49-6). Four recent randomized trials have compared THA with hemiarthropla-sty.12,28,179,294 Two publications10,131 reported a longer term follow-up of the patients in two of these trials.12,28 
Baker et al.12 randomized 81 patients between cemented THA and cemented hemiarthroplasty. The THA patients could walk significantly further and had better outcome as measured by the Oxford hip score at a mean follow-up of 3 years. There were three dislocations in the THA group but none in the hemiarthroplasty group. The requirement for revision was higher in the hemiarthroplasty group (three vs. one for the THA group). They reported a 7- to 10-year follow-up in 2011, which indicated longer survival of patients treated by THA. There was also a trend toward better function, less pain, and fewer reoperations in the THA group. 
Blomfeldt et al.28 randomized 120 patients to have either a cemented THA or a cemented bipolar hemiarthroplasty. Duration of surgery was longer in the THA group and the blood loss was significantly higher, but this was not associated with any increase in the rate of postoperative complications. There were no dislocations in either group. At 4 and 12 months postoperatively, hip function as measured by the Harris hip score was significantly better in the THA group. Health-related quality of life as measured by the Euroquol outcome questionnaire was better in the THA group also, although the difference did not achieve significance. A longer term follow-up of this trial was reported by Hedbeck et al.131 The difference in the Harris hip score continued to increase in favor of the THA group and the quality of life outcome was also significantly better in that group by 48 months. Macaulay et al.179 reported results of a similar study comparing THA with hemiarthroplasty but with a much smaller cohort of patients (17 THA vs. 23 hemiarthroplasty patients). Patients were followed up for 2 years. The results were similar with THA patients, having significantly better SF-36 and WOMAC scores at 24 months. 
The final study was published by van den Bekerom et al.294 in 2011. This looked at a larger cohort of 252 patients older than 70 years comparing cemented THA with cemented bipolar hemiarthroplasty. Duration of surgery was longer and blood loss was higher in the THA group, and at the subsequent follow-up, these authors were able to show no differences in hip function using the Harris hip score. However, there were eight (7%) dislocations in the THA group but none in the hemiarthroplasty group. 

Three-Way Comparisons

There have been three trials, which included a three-way comparison of internal fixation, hemiarthroplasty, and THR for displaced intracapsular fractures. Ravikumar and Marsh241 published a 13-year follow-up of a trial comparing internal fixation, Austin Moore hemiarthroplasty, and cemented THA. They reported better Harris hip scores in the THA group with a lower requirement of revision surgery of 6.75%. This compared with a revision surgery rate of 33% and 24% for the fixation and hemiarthroplasty groups, respectively. The dislocation rates in the arthroplasty groups were unusually high (13% in the hemiarthroplasty group and 20% in the THA group). 
Rogmark et al.250 published a comparison of internal fixation with arthroplasty in a series of 450 patients older than 70 years. Patients randomized to receive arthroplasty were allocated to THA for those with better levels of mobility, so the trial was not strictly a completely random three-way comparison. After 2 years, the rate of failure was 43% in the internal fixation and 6% in the arthroplasty group (p < 0.001). In the internal fixation group, 36% had impaired walking and 6% had severe pain compared with 25% and 1.5%, respectively, in the arthroplasty group (both p < 0.05). The authors subsequently published a longer term follow-up of the series in 2010.167 At the 10-year follow-up, there were 99 failures (45.6%) after internal fixation compared with 17 (8.8%) after replacement. The rate of mortality was the same throughout in all groups at all stages of follow-up. Patient-reported pain and function were similar in both groups at 5 and 10 years. Those with successfully healed fractures had more hip pain and reduction of mobility at 4 months compared with patients with an uncomplicated replacement, and they never attained a better outcome than the latter patients regarding pain or function. 
Keating et al.153,154 reported a randomized three-way comparison with a 2-year follow-up in 298 patients. In that trial the patients in the THA group had significantly better function than the other two groups at 4, 12, and 24 months postoperatively as measured by the Johansson hip rating questionnaire and Euroqol health index. Similar to all other published trials, revision surgery requirement was significantly higher in the internal fixation group (39% vs. 6% for hemiarthroplasty and 9% for THA). This study also incorporated a health economic assessment that demonstrated that the THA group incurred the lowest overall costs of hospital treatment. 

Summary

In summary, the results of these trials support the view that the routine use of reduction and fixation in patients older than 60 years should be avoided and is not the treatment of choice. Several reviews and meta-analyses of the literature have also been published comparing the outcome of THA after femoral neck fractures.24,176,215,251 These have reached similar conclusions to randomized trials, namely that THA is associated with a low rate of complications and better functional outcomes than other methods of treatment. 
There is an accumulating body of evidence that surgeons should be making increasing use of THA in the fit older patient without cognitive impairment who is an independent community ambulator. It should be noted that only about 25% to 30% of patients presenting with femoral neck fractures will fulfill those criteria. For the majority of older patients, a modern hemiarthroplasty is the current treatment of choice. Although the existing literature suggests that cemented stems are better, this is based largely on literature using outdated uncemented implants such as the Austin Moore prosthesis. More data are required on modern uncemented stems. 

Special Situations of Femoral Neck Fractures

Displaced Femoral Neck Fractures in Young Adults

Hip fractures are uncommon in patients younger than 60 years and account for only 3% of all hip fractures. In younger adults these injuries are often the result of high-energy trauma.92,315 However, about half of the patients are somewhat older, usually between the age of 40 and 60 years. In these patients, there are often predisposing conditions rendering them more liable to sustain a hip fracture. These factors include chronic diseases associated with osteoporosis, steroid treatment, and alcohol abuse.315 A recent study152 identified smoking as a significant risk for hip fractures in women younger than 65 years. 
Another recently published series78 addressed the issue of risk factors for failure after internal fixation in patients younger than 60 years, with displaced intracapsular fractures. In a series of 122 patients, union occurred in 83 (68%). Complications occurred in 39 patients (32%) at a mean of 11 months (0.5 to 39). The rate of nonunion was 7.4% (n = 9) and of AVN was 11.5% (n = 14). Failures were more common in patients older than 40 years (p = 0.03). Univariate analysis identified that delay in time to fixation (>24 hours), alcohol excess, and preexisting renal, liver, or respiratory disease were all predictive of failure (all p < 0.05). Of these, alcohol excess, renal disease, and respiratory disease were most predictive of failure on multivariate analysis. They concluded that in younger patients with femoral neck fractures and a history of alcohol abuse, renal or respiratory disease, arthroplasty should be considered as an alternative treatment. 
If the fracture is undisplaced, it may be treated by reduction and fixation as a scheduled urgent procedure. A displaced intracapsular hip fracture in a young patient requires more urgent treatment. These fractures should be treated by reduction and fixation in suitable patients as soon as possible. In most patients a satisfactory reduction can be achieved closed. If the reduction is not adequate, then open reduction can be considered. This is usually performed through a Watson-Jones approach107 that conserves the femoral blood supply. A capsulotomy in line with the femoral neck can be performed to visualize the fracture. Reduction can be assisted by applying traction to the femur using a bone hook on the greater trochanter to disimpact the fracture. Control of the proximal fragment can be achieved by inserting a 2-mm Kirschner wire into the femoral head, which can act as a joystick and allow manipulation of the head to facilitate reduction. Although this may facilitate a better anatomic reduction, it may be at the expense of increasing the rate of nonunion. The overall rate of nonunion with open reduction has been 11% in comparison with 5% for closed reduction in younger patients.67 
The results of femoral neck fracture fixation in younger patients are good in most cases, but rates of nonunion and AVN are significant. The results of a number of studies are given in Table 49-9. Union rates vary from 73% to 100% and AVN from 10% to 40%. A meta-analysis67 estimated the overall rates of nonunion and AVN to be 8.9% and 23%, respectively. Although intuitively early reduction and fixation would seem advisable, there is not a strong relationship between the timing of surgery and nonunion or AVN. In their series Jain et al.140 reported no AVN in 15 patients fixed within 12 hours compared with a 26% incidence in patients with a delay to fixation (6/23). However, in another larger series292 and a meta-analysis of the literature,67 there was no relationship of timing of surgery to development of nonunion or AVN. The quality of reduction has an influence on the rate of complications. In particular, a varus reduction has been shown to be associated with a 13-fold increase in the likelihood of fixation failure.51 
Table 49-9
Results of Studies Investigating Reduction and Internal Fixation of Displaced Femoral Neck Fractures in Patients Younger Than 60 Years
Authors No. of Fractures Nonunion Avascular Necrosis
Zetterberg et al.315 93 1% 46.2%
Swiontkowski et al.282 25 0 20.0%
Tooke and Favero288 18 5.5% 33.3%
Gray and Parker113 58 6.97% 8.6%
Robinson et al.248 32 15.6% 21.8%
Gautam et al.107 25 4.0% 12.0%
Haidukewych et al.123 83 7.2% 20.4%
Duckworth et al.78 122 7.4% 11.5%
Total 456 5.9% 21.9%
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For Pauwel’s Type III fractures, there is some evidence that a fixed angle device might be preferable to cannulated screws or a sliding hip screw. In their series Liporace et al.172 reported that the nonunion rate with fixed angle devices for these fractures was 8% compared with a rate of 19% with sliding devices. The numbers in the study were not large, but for these very unstable patterns in younger patients a fixed angle device may be a better choice. 

Ipsilateral Femoral Neck and Shaft Fractures

This injury combination is usually found in young adults with high-energy femoral shaft fractures. However, it may occur as an iatrogenic injury due to injudicious placement of the proximal entry point for antegrade femoral nailing. Between 2% and 6% of femoral neck fractures in young adults will have an ipsilateral hip fracture.2,289,310,311 The injury is easily missed particularly if the fracture is undisplaced or the radiographs of the proximal femur are inadequate or of poor quality. Careful scrutiny of the radiographs is necessary in all cases. In the event of the fracture being recognized before surgery the options are as follows: 
Each of these options has something to recommend it. In this situation the femoral neck fracture takes priority—it is most important to reduce and fix this fracture anatomically. If the femoral neck fracture is undisplaced, an antegrade second- or third-generation femoral nail is recommended. If the femoral neck fracture is displaced and any difficulty is anticipated in achieving a closed reduction, screw fixation and retrograde nailing of the femoral shaft fracture is probably best. Plating of the femoral shaft fracture is usually reserved for cases where the shaft fracture is in the distal third of the bone. In general plating of femoral shaft fractures is technically demanding and in the case of open plating is associated with higher rates of nonunion than intramedullary nails. The options that utilize nail fixation of the femoral shaft component are therefore probably safer. 

Femoral Neck Fractures in Rheumatoid Arthritis

Femoral neck fractures are not infrequent in patients with rheumatoid arthritis due to the osteoporosis associated with the condition. In published reports, the results of reduction and fixation in these cases have been poor.121,276,279 Stephen276 reported on 36 intracapsular fractures. Of 24 treated by prosthetic replacement, 16 (66%) were reported to have had a satisfactory outcome. Four undisplaced fractures were fixed but two developed AVN. Eight displaced fractures were reduced and fixed, but none of these united. Hadden et al.121 reported only eight satisfactory results in 27 displaced fractures in rheumatoid patients treated with reduction and fixation. Similarly Strömqvist et al.279 reported complications in 19 of the 20 displaced fractures treated by reduction and fixation. The experience of other authors in subsequently published series has been similar.7,34,130 Unless the patient is very young or the fracture is undisplaced, displaced intracapsular hip fractures in these patients should be treated with an arthroplasty. Satisfactory results have been reported with both bipolar and THA. 

Stress Fractures

Stress fractures of the femoral neck may be fatigue fractures or insufficiency fractures. The former occur in normal bone as a result of repetitive cyclical loading, and the latter occur in osteoporotic bone due to normal physiological loads. Fatigue fractures most frequently occur in young adults and have been reported in military recruits with an incidence varying from 3% to 8%.103,233 Insufficiency fractures occur in elderly patients and are estimated to account for 2% to 3% of hip fractures.136 Most proximal femoral stress fractures are intracapsular in location. The fracture is often incomplete and is located either on the superior or inferior surface of the femoral neck (Fig. 49-18). Fractures on the superior surface of the neck are tension fractures and are more liable to become complete and displaced. They should be treated with internal fixation. Compression fractures are more common in younger patients. They are inherently more stable and may initially be treated nonoperatively with 6 to 8 weeks of protected weight-bearing. If the fracture fails to heal, internal fixation is indicated. 
Figure 49-18
 
A: A 48-year-old woman with an inferior femoral neck stress fracture. The patient had previously undergone fixation of the fracture with a sliding hip screw, but the fracture recurred after implant removal. B: The fracture healing after sliding hip screw fixation.
A: A 48-year-old woman with an inferior femoral neck stress fracture. The patient had previously undergone fixation of the fracture with a sliding hip screw, but the fracture recurred after implant removal. B: The fracture healing after sliding hip screw fixation.
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Figure 49-18
A: A 48-year-old woman with an inferior femoral neck stress fracture. The patient had previously undergone fixation of the fracture with a sliding hip screw, but the fracture recurred after implant removal. B: The fracture healing after sliding hip screw fixation.
A: A 48-year-old woman with an inferior femoral neck stress fracture. The patient had previously undergone fixation of the fracture with a sliding hip screw, but the fracture recurred after implant removal. B: The fracture healing after sliding hip screw fixation.
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Femoral Neck Fractures in Paget’s Disease

Fractures of the femoral neck are considered to be less frequent than intertrochanteric or subtrochanteric fractures in Paget’s disease. However, the disease can produce a coxa vara deformity, and this is associated with an increased risk of failure with reduction and fixation. The results in the literature are strongly in favor of arthroplasty for patients with Paget’s disease who present with a displaced intracapsular fracture. Dove76 reported a nonunion rate of 75% after fixation, and Milgram193 and Grundy119 also reported a high complication rate after fixation. Although arthroplasty is the preferred option, it is often not a straightforward undertaking. The bone may be sclerotic or very vascular, both characteristics that may present technical difficulties. If the acetabulum is involved in the disease, the results of hemiarthroplasty are not as good16,200 and THR is a better choice in this situation.264 

Metastatic Femoral Neck Fractures

Intracapsular pathologic fractures of the femoral neck are less common than those in the pertrochanteric region. They should be suspected in patients with a history of carcinoma with a predilection for bony spread (lung, breast, prostate, kidney, thyroid), those who present with minimal or no history of trauma, and patients with evidence of a lytic lesion in the femoral neck. Depending on the primary source, some additional preoperative investigation and preparation may be necessary. Hypercalcemia may be an accompanying feature, and this needs to be corrected before surgery. Imaging of the rest of the skeleton is necessary to diagnose disease elsewhere. It is particularly important to establish that the femoral shaft on the same side is free of disease since the presence of metastatic lesions in the femur will clearly influence surgical management. 
For the majority of patients with a femoral neck fracture due to metastatic disease, an arthroplasty is the most appropriate treatment. For patients with limited functional demands or life expectancy, a bipolar hemiarthroplasty is a reasonable choice. Patients with a more favorable prognosis and better function should be considered for THA. Lesions that are solitary metastases or the presence of additional lesions in the proximal femur may necessitate proximal femoral replacement. 

Femoral Neck Fractures in Cerebral Palsy and Other Conditions with Muscle Spasticity

Patients with muscle spasticity due to cerebral palsy or other neurologic conditions may occasionally sustain a femoral neck fracture. If this is undisplaced then fixation is the treatment of choice. Careful radiological assessment of the femoral neck is required. Some degree of dysplasia is often present. The femoral neck and head are frequently hypoplastic, limiting space for implants. In cerebral palsy there is often marked anteversion of the femoral neck, which needs to be anticipated when fixation is undertaken. For patients with displaced fractures, fixation may still be the treatment of choice in younger patients. In older patients an arthroplasty may be a better choice. Preoperative templating in these patients is advisable to ensure appropriate stem sizes are available at the time of surgery. 

Author’s Preferred Method of Treatment for Femoral Neck Fractures

My treatment of intracapsular hip fractures is based on a number of considerations: Whether the fracture is displaced, the age of the patient, cognitive state, functional demands, and the presence of other medical comorbidities. A rational decision based on good clinical evidence can be made for most of these patients. My approach to treatment selection is summarized in the algorithm illustrated in Figure 49-19
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Figure 49-19
Algorithm for treatment of femoral neck fractures.
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Undisplaced Femoral Neck Fractures

I treat undisplaced femoral neck fractures with cannulated screw fixation, irrespective of age or other considerations. The majority of these fractures will heal uneventfully following this treatment, and the procedure can be carried out with a very limited surgical exposure associated with low postoperative morbidity. I generally use three screws in parallel alignment on the AP and lateral views. Although nonoperative treatment is an option, the risk of displacement is considerable. Unless the patient presents late and is completely asymptomatic, I do not manage any of these injuries nonoperatively. I follow up independently mobile patients until there is evidence of fracture union. 

Displaced Intracapsular Femoral Neck Fractures

There are three main categories of patients to consider with displaced fractures: Younger patients, fit older patients, and older patients with lower functional demands due to cognitive impairment, limited mobility, or medical comorbidities. 

Younger Patients

In patients younger than 60 years, I prefer early reduction and internal fixation with cannulated screws in the majority. When feasible I carry out the procedure as soon as possible after admission, although the evidence in support of urgent surgical intervention is limited. On the other hand, there is evidence to suggest that fixation up to a week following injury has similar results to procedures performed on an urgent basis. In a younger patient, I would therefore consider reduction and fixation even in patients presenting within this time frame after injury. I prefer to use cannulated screws rather than a sliding hip screw device with a short side plate. There is no difference in the outcome, but the cannulated screws are a less bulky implant. I use three cannulated screws, although as already indicated, the evidence that this is superior to use of two screws is limited. Implant position has been debated, but there is evidence that parallel placement on the AP and lateral views is associated with good results. I usually place the screws in an inferior, central, and superior position on the AP view and superimpose them in the central portion of the head on the lateral view. Postoperatively, patients can be mobilized touch weight-bearing on crutches. Instructions to remain non-weight-bearing are not logical. This actually increases the forces across the fracture in patients who can comply, but most elderly patients will be unable to fully non-weight-bear in any event. Patients will need regular orthopedic follow-up to ensure fracture healing occurs uneventfully and detect complications, particularly fixation failure, nonunion, and AVN. In younger patients, I see patients at 6 weeks, 3 months, and 6 months postoperatively. Thereafter, I review patients on a 6-monthly basis until they are 2 years following surgery. If there are no complications evident at that stage, patients can be discharged. In older patients or patients living remotely from the treating institution, this pattern of follow-up may be impractical. Follow-up to fracture union is advisable, and patients can be referred by the family or institution doctor if complications develop. 
In patients with risk factors such as chronic disease predisposing to osteoporosis or alcohol abuse, I often consider some form of arthroplasty, particularly if the patient is older than 40 years. The failure rate of fixation in these patients is very high. Patients with renal failure, rheumatoid arthritis, or who are on long-term corticosteroid treatment are very poor candidates for fixation. If the level of function is good in these patients, I prefer treatment with THA. Patients with a history of chronic alcohol abuse are at high risk for dislocation following THA, especially if alcohol withdrawal symptoms develop in the early postoperative period. I therefore treat the fracture in these patients with a cemented bipolar hemiarthroplasty if there is evidence of ongoing alcohol abuse at the time of admission. 

Fit Older Patients

Although it has been a controversial choice in the past, there is now an accumulating body of evidence from randomized trials to support the use of THA for fit older patients with a displaced intracapsular hip fracture. In patients older than 60 years who are independently mobile in the community, I now use this treatment option as my first choice. Many surgeons might be reluctant to consider THA for patients in their sixties, but the evidence from randomized trials indicates that the fixation failure rate even in these relatively “younger” patients is no different from that in patients older than 70 years. The functional outcome is also better following THA. 
My preference is a direct lateral surgical approach and a cemented THA. I use a single dose of a broad-spectrum antibiotic at induction of anesthesia to prevent infection and a low-molecular-weight heparin for deep vein thrombosis (DVT) prophylaxis. Postoperatively, patients are mobilized weight-bearing as tolerated. The risk of dislocation is higher than with THA for osteoarthritis, and patients need to be carefully instructed by the physiotherapist about precautions to take to minimize the risk of dislocation. Since these patients are fit and active, I routinely follow them up at 6 weeks, 3 months, 6 months, and 1 year postoperatively to detect any postoperative complications at an early stage. 
It has to be stressed that only about 25% of patients with a displaced intracapsular hip fracture are completely independent community ambulators with no cognitive impairment who merit consideration of this treatment option. The recommendation to use THA will apply to a very limited number of patients in most orthopedic units. An orthopedic unit with a catchment population of 250,000 will treat 250 to 300 hip fractures a year. Half of these will be intracapsular, and 85% of this group will be displaced. Even with a workload of 300 hip fractures per year, only about 25 to 35 patients would therefore fulfill the criteria for THA. 

Displaced Fractures in Older Patients with Limited Functional Demands

The majority of displaced fractures occur in elderly female patients. The incidence of significant medical comorbidities is 70%, and 25% to 30% have a degree of cognitive impairment. The results of reduction and fixation are very poor in this group, and I no longer use this procedure for these patients. My preference is to use a modern cemented bipolar hemiarthroplasty for the majority of these patients. Although there is no evidence to support the use of a bipolar rather than a unipolar implant, the modularity of the bipolar arthroplasties is advantageous in achieving correct leg length and soft tissue tension at the time of surgery. Even patients with dementia may be mobile within the home environment or community, and a modern cemented implant is associated with better function than an older uncemented implant such as the Austin Moore or Thomson hemiarthroplasty. The latter implants are now obsolete. 
The surgical approach, antibiotic, and DVT prophylaxis are as described for THA. Postoperatively, patients can be mobilized weight-bearing as tolerated. Arrangements for follow-up of these patients will vary. If patients have been in hospital for a sufficient duration to detect early wound problems, I do not routinely recall them for outpatient follow-up. If there has been any wound problem then early outpatient review is advisable to detect any sign of deep infection (Table 49-10). 
Table 49-10
Femoral Neck Fractures—Pearls, Pitfalls, and Treatment Considerations
Pearls and Pitfalls for Reduction and Fixation
Consider the possibility of predisposing causes in younger patients that may contraindicate fixation, such as alcohol abuse, rheumatoid arthritis, chronic renal failure, other chronic disease, or steroid use
Gentle positioning on the table is important to avoid increasing fracture displacement
Cautious application of traction with slight internal rotation
Avoid excessive traction to minimize the risk of valgus reduction
Three cannulated screws are adequate for fixation
Avoid multiple drill holes in the lateral cortex, which increases the risk of postoperative subtrochanteric fractures
Pearls and Pitfalls for Hemiarthroplasty
Do not use older designs (Austin Moore/Thompson) in active patients
Employ a lateral approach to minimize the risk of dislocation
Cut the neck to allow collar support
Carefully ream and insert the implant to avoid splitting the femur
A modular prosthesis is preferred to achieve correct soft tissue tension and leg length
If the femoral shaft is split during reaming, employ cerclage wires and convert to a cemented stem
Use a gentle reduction maneuver and avoid excess rotational force to minimize the risk of femoral shaft fractures
Pearls and Pitfalls for Total Hip Arthroplasty
Use in fit, active patients without cognitive impairment
Avoid in alcohol abusers
Lateral approach to minimize the risk of dislocation
Cautious reaming of acetabulum to avoid medial wall penetration or overreaming of the anterior/posterior wall
Consider using uncemented prosthesis in patients with cardiovascular morbidity to minimize the risk of cement reaction
Considerations for Treatment Options
Displaced or undisplaced fractures
Age of the patient
Cognitive state
Functional demands
Medical comorbidity
Conditions/medication predisposing to osteoporosis
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Complications in Femoral Neck Fractures

Mortality in Femoral Neck Fractures

Mortality after femoral neck fractures is significant. The results from clinical trials, reported series, hip fracture audits, and national databases or joint registries give estimates of a 15% hospital mortality and a 30% mortality at 1 year. There is no significant difference in mortality rates for pertrochanteric and intracapsular neck fractures.111 These mortality rates are four to five times higher than in the comparable nonhip fracture population of the same age.313 In patients with significant cognitive impairment the 1-year mortality rises to 50%. Not surprisingly, the presence of concomitant medical comorbidities increases the risk of death after surgery. This applies particularly to patients with significant cardiorespiratory conditions.81,151,196,230 Renal impairment with elevated urea and creatinine was associated with doubling of the 1-year mortality in one study.168 Women have a lower rate of mortality than men.151,162,196,230,246 The mortality rates for undisplaced fractures are higher if they are treated with a hemiarthroplasty as opposed to internal fixation. Sikand et al.262 reported a 38% mortality at 1 year following hemiarthroplasty compared with 11% for fixation for undisplaced fractures. 

Delay to Surgery in Femoral Neck Fractures

Hip fractures comprise a significant proportion of the operative workload of orthopedic trauma, and delays to surgery are common due to the volume of cases. The relationship of mortality to delay to surgery remains controversial. Dolk73 analyzed a small series and found no difference in mortality between patients who had immediate surgery and those who had surgery up to 48 hours after admission. Orosz et al.208 compared mortality and complication rates in patients having surgery within 24 hours and after that period. They found no difference in mortality or the functional outcome, but patients who had early surgery had less pain and a trend to lower complication rates. Similarly, larger population studies have not shown any reduction in mortality if surgery is performed within 24 hours of admission.180,280 However there are a number of studies that have looked at longer delays. Doruk et al.75 reported a significant increase in mortality with delays beyond 5 days, and Moran et al.194 found a significant increase in mortality with delays beyond 4 days. It may be that delays of less than this magnitude are important, but the effect is less and has not been picked up in these studies with cohorts of between 2,000 and 4,000 patients. 
In a larger study of in-hospital mortality with a cohort of over 129,000 patients, Bottle and Aylin36 found an increase in mortality with an odds ratio of 1.27 for a 24-hour delay to surgery after adjusting for comorbidity. Based on the available evidence therefore, it would seem that mortality can be reduced with early surgery and the aim for most patients should be to have surgery within 48 hours of admission. 
The magnitude of surgery might also be expected to influence mortality, but the effect is weaker than might be expected. Bhandari et al.24 assessed this in a meta-analysis of studies comparing arthroplasty with fixation.38,69,141,143,145,198,221,236,241,250,263,272,281,285,295,299 The average mortality rates in the first 4 months were 9% (range, 4% to 20%) for arthroplasty compared with 6% (range, 0% to 12%) for fixation. At 1 year, the average mortality rates were 23% (range, 4% to 48%) for arthroplasty compared with 20% (range, 0% to 65%) for fixation. These slight differences did not achieve statistical significance. The type of arthroplasty used had no influence. 

Infection in Femoral Neck Fractures

The risk of infection is lower with internal fixation than arthroplasty as might be expected. With internal fixation the operating time is shorter, the surgical exposure is minimally invasive, and the implants used are smaller. In comparative studies, infection rates following internal fixation range from 0% to 10% compared with arthroplasty infection rates of 0% to 18%.24 The infection rate in modern orthopedic practice should be low. A recent series of over 3,000 intracapsular hip fractures recorded rates of deep infection of 1.26% for hemiarthroplasty and a rate of 0.18% after fixation.128 
Infection following internal fixation usually has less serious consequences than deep infection following arthroplasty. Removal of the implants after fracture healing may be all that is required. There is also the option of later conversion to arthroplasty if the fracture fails to unite. Deep infection after arthroplasty is a very difficult management problem in these elderly frail patients. The options of excision or exchange arthroplasty are further major interventions and are likely to be poorly tolerated in patients with medical comorbidities. Excision arthroplasty to control infection is generally associated with very poor postoperative mobility. Older patients are usually wheelchair bound after this procedure. Immediate exchange arthroplasty has quite good results after arthroplasty for osteoarthritis, with eradication of infection in 85% of cases. The results are not likely to be as good in the hip fracture population, with a much frailer population, although little has been written on the topic. 
The management of deep infection after hemiarthroplasty or THA has to take a number of factors into account, including the age of the patient, functional demands, medical comorbidities, and the infecting organism. If the organism is sensitive to common antibiotics, one option is to opt for nonoperative management if the patient is frail, and try to suppress the infection with low-dose antibiotic therapy. Unfortunately, carriage of organisms such as methicillin-resistant Staphylococcus aureus is high in this population, and this organism is a common cause of deep infection in these cases.191 Nonoperative management with antibiotic suppression is less likely to be successful in the presence of this or other resistant organisms. 
Less radical surgical options include debridement of the hip, with replacement of some of the implant, such as the bipolar head, if applicable. In some patients, deliberate creation of a fistula to allow drainage in the inferior part of the wound is an option if excision and reimplantation is not planned in the short to medium term. In fitter patients who will tolerate more major surgery, my preference is to carry out an excision arthroplasty and a reimplantation when infection is under control. This is also the best option for infections due to resistant organisms where antibiotic suppression options may be limited, or there are unwanted side effects of antibiotic therapy. 

Deep Venous Thrombosis and Pulmonary Embolism in Femoral Neck Fractures

Thromboembolic complications are a well-recognized complication of hip fracture, and surgery is required to treat the injury. Zahn et al.314 found venographic evidence of DVT in 13 of the 21 (62%) patients whose surgery had been delayed beyond 48 hours. Other authors have estimated that one third to one half of patients with a hip fracture will develop DVT.120,255 However, larger studies281 have indicated that the incidence of symptomatic DVT may be lower than this. Todd et al.287 recorded a 6% incidence of DVT and a 2% incidence of fatal pulmonary embolism (PE). McNamara et al.189 reported a rate of symptomatic venous thromboembolic complications of 2.2% in a series of 5,300 patients with hip fractures. The rate of DVT was 1.5% and PE was 0.7%. In a review of the literature on the topic, Gillespie et al.110 reported that radiographically proven DVT occurred in 45% of cases and clinically apparent DVT in 7% of patients. Nonfatal pulmonary emboli occurred in 8% of patients and fatal pulmonary emboli in 4%. There is now an accumulating body of evidence to support the view that DVT prophylaxis is effective in reducing the risk of DVT in patients with hip fractures. The most commonly used options for prophylaxis after hip fractures include aspirin, heparin, dextran, and pneumatic compression devices. 
Mechanical prophylaxis using foot pumps or pneumatic compression devices has been shown to reduce the risk of asymptomatic deep venous thrombosis after hip fractures in a meta-analysis124 of trials published assessing effectiveness of these devices. The incidence of DVT was reduced from 19% to 6%. There was no demonstrable effect on symptomatic DVT or mortality. 
Heparin is used as either low-dose unfractionated heparin or low-molecular-weight heparin. Aspirin was shown to be more effective than placebo in DVT prevention. A meta-analysis of trials124 using aspirin has indicated that it is effective in reducing asymptomatic DVT (42% to 36%), symptomatic DVT (1.5% to 1%), all pulmonary emboli (1.6% to 0.8%), and fatal pulmonary emboli (0.8% to 0.4%). These conclusions were based mainly on the largest trial that was the Pulmonary Embolism Prevention (PEP) study235 in which authors calculated that aspirin prevented four fatal pulmonary emboli per 1,000 hip fracture patients. 
Handoll et al.124 carried out a meta-analysis of 31 trials evaluating various combinations of heparin and pneumatic compression devices for prevention. Unfractionated and low-molecular-weight heparins reduced the incidence of DVT from 42% in control groups to 26%. There was no demonstrable reduction in either PE or mortality. Five trials compared unfractionated and low-molecular-weight heparin, but no conclusive differences were shown. Five trials of mechanical pumping devices were methodologically flawed but seemed to show a reduction in the incidence of DVT (7% vs. 22%). Compliance may be an issue with these devices. 
Warfarin has not been popular as a prophylactic agent in hip fracture patients. Many of these patients are elderly, already on multiple pharmacologic agents, and the risks associated with warfarin administration make it an unpopular choice for this group. Fondaparinux has been evaluated in randomized trials as a prophylactic agent after hip fractures. In one trial,87 it was compared with enoxaparin for thromboprophylaxis. Fondaparinux was associated with an 8.3% rate of early thromboembolic complications compared with a rate of 19% in the enoxaparin group. In a subsequent trial,88 a 3-week period of prophylaxis with fondaparinux was more effective than a short-duration regimen (6 to 8 days postoperative course). 
Based on current evidence, the use of a prophylactic agent (heparin, aspirin, or mechanical pumps) is justified as these agents seem to protect against DVT after hip fractures. There is some evidence that the risk of pulmonary embolus is reduced, but this is uncertain. Based on current evidence, a low-molecular-weight heparin or aspirin is probably the safest choices for thromboprophylaxis in patients with a femoral neck fracture supplemented by a pneumatic compression device if tolerated by the patient. 

Fixation Failure and Nonunion in Femoral Neck Fractures

Fixation failure and nonunion are the main modes of failure following fixation of displaced or undisplaced femoral neck fractures (Fig. 49-20). The two problems are difficult to distinguish since most displaced fractures take a long time to heal after fixation, which increases the risk of fixation failure. In undisplaced fractures, failure of fixation is a rare complication. Nonunion is more common and is reported in up to 7% of cases. Both complications are much more frequent following reduction and fixation of displaced fractures. The incidence of nonunion and/or fixation failure requiring revision surgery is between 30% and 50% for displaced fractures. 
Figure 49-20
AP (A) and lateral (B) radiographs of an undisplaced intracapsular hip fracture.
 
C. AP radiograph at 3 months showing collapse with loss of fixation and non-union.
C. AP radiograph at 3 months showing collapse with loss of fixation and non-union.
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Figure 49-20
AP (A) and lateral (B) radiographs of an undisplaced intracapsular hip fracture.
C. AP radiograph at 3 months showing collapse with loss of fixation and non-union.
C. AP radiograph at 3 months showing collapse with loss of fixation and non-union.
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Detection of the problem is usually obvious with increasing hip pain, shortening of the leg due to collapse and loss of reduction, and radiological evidence of fixation failure. In the majority of cases, the best option for treatment is conversion to an arthroplasty. In fit patients I prefer THR. In older patients, conversion to a hemiarthroplasty is an alternative if the acetabulum is normal. Infection is an occasional contributory cause and should be considered in all cases. If there is any evidence of infection, excision arthroplasty may have to be considered in the first instance with an interval arthroplasty at a later stage. 
It is often assumed that conversion of failed fixation to either a hemi or total arthroplasty is a straightforward solution to the problem. Studies that have compared the outcome of primary versus revision fixation do not bear this out.20,31,99,188 The rates of dislocation and infection are approximately double those seen following primary arthroplasty for femoral neck fractures. The functional outcome is also inferior, and there is evidence that survivorship of these revision prostheses is shorter. In one randomized trial comparing fixation to bipolar and THA, the arthroplasty complication rate in the fixation group was identical to the two arthroplasty groups, reflecting higher rates of arthroplasty complications in patients with failed fixations converted to arthroplasty.153 

Nonunion in Young Patients

In younger patients, conversion to arthroplasty may not be the ideal first choice, particularly if the patient is younger than 40 years and has no other medical comorbidities. In these patients the alternatives include revision of fixation, vascularized bone graft, or a valgus osteotomy if the nonunion or fixation failure is recognized before complete displacement of the head occurs.274 Revision of fixation augmented by a vascularized bone graft is a reasonable option if there has been no loss of reduction. Meyers et al.192 described the use of a vascularized quadratus femoris graft to prevent AVN after femoral neck fractures (Fig. 49-21) now more commonly used to achieve union in patients with delayed or nonunion.305 This technique has been reported to be successful in achieving union in 95% of cases. In a series of 42 younger patients presenting at a mean of 9 months postinjury, Vallamshetla et al.293 reported a union rate of 86% using a quadratus femoris graft associated with open reduction, internal fixation, and bone grafting of the nonunion. 
Figure 49-21
Meyer’s graft.
 
A: “T” incision of the posterior capsule. B: Mapping out the quadratus femoris graft. C: The trough is curetted out from the intertrochanteric lineup into the femoral head. A small tunnel is created up under the articular surface of the femoral head to lever the graft into position. Once the graft is inserted, a 3.5-mm cancellous screw and washer is inserted from posterior to anterior to compress the graft and support the comminuted posterior cortex.
A: “T” incision of the posterior capsule. B: Mapping out the quadratus femoris graft. C: The trough is curetted out from the intertrochanteric lineup into the femoral head. A small tunnel is created up under the articular surface of the femoral head to lever the graft into position. Once the graft is inserted, a 3.5-mm cancellous screw and washer is inserted from posterior to anterior to compress the graft and support the comminuted posterior cortex.
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Figure 49-21
Meyer’s graft.
A: “T” incision of the posterior capsule. B: Mapping out the quadratus femoris graft. C: The trough is curetted out from the intertrochanteric lineup into the femoral head. A small tunnel is created up under the articular surface of the femoral head to lever the graft into position. Once the graft is inserted, a 3.5-mm cancellous screw and washer is inserted from posterior to anterior to compress the graft and support the comminuted posterior cortex.
A: “T” incision of the posterior capsule. B: Mapping out the quadratus femoris graft. C: The trough is curetted out from the intertrochanteric lineup into the femoral head. A small tunnel is created up under the articular surface of the femoral head to lever the graft into position. Once the graft is inserted, a 3.5-mm cancellous screw and washer is inserted from posterior to anterior to compress the graft and support the comminuted posterior cortex.
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Meyers Bone Graft

A posterior approach is developed to the hip, and a posterior capsulotomy is performed. The femoral neck nonunion is identified, and fibrous tissue is cleared from the nonunion site. The quadratus femoris insertion on the posterior aspect of the femur is elevated with a length of 4 cm, a width of 1.5 cm and a depth of 1 cm. A trough to receive the bone block is cut into the posterior aspect of the femoral neck, bridging the nonunion site. The bone block is placed in the trough and fixed in place with screws. 

Proximal Femoral Osteotomy

Unfortunately, the more usual scenario is a patient who presents with some loss of reduction, with the femoral head displacing into a varus position. In this situation, the best option is a proximal femoral valgus osteotomy.229,274 This procedure converts the fracture plane from a vertical orientation to a transverse one, with compression created at the site of the nonunion (Fig. 49-22). Careful preoperative planning is necessary. The usual aim is to change the femoral neck angle to 150 degrees. This degree of correction will be sufficient to restore the fracture to a transverse orientation in most cases. A blade plate is the most popular fixation device for this procedure. I generally use a 130-degree blade plate, but the exact implant depends on the correction required. The channel for the blade is made before the osteotomy, which is carried out at the level of the lesser trochanter. A wedge of bone is then excised to achieve the correction, and the blade plate is used to fix the osteotomy. Marti et al.182 reported on 50 younger patients treated with this technique. Seven failed and required conversion to an arthroplasty. The remainder healed but there was radiographic evidence of AVN in 22 (44%) at a mean follow-up of 7 years, although most of the patients with this complication were reported to be asymptomatic. Anglen5 reported on 13 patients with union occurring in all cases although 2 went on to develop AVN. Sringari et al.274 reported on achieving union in 18 of the 20 (90%) patients treated with a valgus osteotomy. 
Figure 49-22
 
A, B: AP and lateral radiographs of a displaced intracapsular hip fracture 4 months after treatment with a sliding hip screw that has been inserted incorrectly. The fracture has not been reduced and coxa vara is present. The hip screw is high and the plate is unnecessarily long. C: AP radiograph showing correction of deformity with a valgus osteotomy. A 130-degree blade plate was used with a closing wedge subtrochanteric osteotomy to change the femoral neck angle to 150 degrees. D: AP radiograph 9 months after osteotomy. The osteotomy and femoral neck fracture have united and there is no sign of avascular necrosis.
A, B: AP and lateral radiographs of a displaced intracapsular hip fracture 4 months after treatment with a sliding hip screw that has been inserted incorrectly. The fracture has not been reduced and coxa vara is present. The hip screw is high and the plate is unnecessarily long. C: AP radiograph showing correction of deformity with a valgus osteotomy. A 130-degree blade plate was used with a closing wedge subtrochanteric osteotomy to change the femoral neck angle to 150 degrees. D: AP radiograph 9 months after osteotomy. The osteotomy and femoral neck fracture have united and there is no sign of avascular necrosis.
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Figure 49-22
A, B: AP and lateral radiographs of a displaced intracapsular hip fracture 4 months after treatment with a sliding hip screw that has been inserted incorrectly. The fracture has not been reduced and coxa vara is present. The hip screw is high and the plate is unnecessarily long. C: AP radiograph showing correction of deformity with a valgus osteotomy. A 130-degree blade plate was used with a closing wedge subtrochanteric osteotomy to change the femoral neck angle to 150 degrees. D: AP radiograph 9 months after osteotomy. The osteotomy and femoral neck fracture have united and there is no sign of avascular necrosis.
A, B: AP and lateral radiographs of a displaced intracapsular hip fracture 4 months after treatment with a sliding hip screw that has been inserted incorrectly. The fracture has not been reduced and coxa vara is present. The hip screw is high and the plate is unnecessarily long. C: AP radiograph showing correction of deformity with a valgus osteotomy. A 130-degree blade plate was used with a closing wedge subtrochanteric osteotomy to change the femoral neck angle to 150 degrees. D: AP radiograph 9 months after osteotomy. The osteotomy and femoral neck fracture have united and there is no sign of avascular necrosis.
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Fixation with a blade plate is the usual implant used, but surgery may be technically difficult. More recently, Khan et al.155 reported on 16 patients treated with valgus osteotomy for femoral neck nonunion using a sliding hip screw and 120-degree double-angle barrel plate. Union was achieved in 14 of the 16 cases. This implant is easier to insert correctly for most surgeons who will be more familiar with its use. 

Avascular Necrosis in Femoral Neck Fractures

AVN is a well-recognized complication of femoral neck fractures but is not frequently encountered in clinical practice. This is due to a gradual increase in the use of arthroplasty rather than fixation to treat these injuries over the past two decades. The falling incidence of this complication can be seen by three studies published in separate decades. Barnes et al.15 in a study of over 1,500 femoral neck fractures treated by internal fixation reported an incidence of AVN in 24% of women and 15% of men. The incidence was lower in undisplaced fractures (16%) than in displaced fractures (27.6%). In the meta-analysis of Lu-Yao et al.,176 the incidence of fixation failure and nonunion is 33% compared with a rate of AVN of 16% (95% CI 11% to 19%). By the time of publication of the meta-analysis of Bhandari et al.,24 the reported rate of AVN had declined to a mean of 6.9% (range, 0% to 22%). A very similar incidence of AVN of 6.6% was reported in a series of 1,023 patients by Loizou and Parker.174 There are several possible explanations for the decline in the incidence of this problem. There has been a gradual reduction in the widespread use of reduction and fixation for displaced fractures, the incidence of AVN is lower with undisplaced fractures, and surgeons may now be choosing patients more carefully for reduction and fixation so that only patients with a favorable prognosis are treated with this technique. In their study Loizou and Parker174 identified age of less than 60 years and female sex as factors associated with a higher risk of the complication. 
The diagnosis can be made on the basis of typical plain radiographic appearances, but these may not be evident for a long period. Single photon-emission computed tomographic scan has been shown to be an accurate predictor of AVN if uptake is less than 90%.277 MRI scanning will detect the problem before plain radiographs, but it is not an accurate predictor of AVN in the early weeks after injury.9,273 
The complication tends to occur late after surgery. Fractures treated by reduction and fixation take a long time to heal, and AVN usually presents after union. Barnes et al.15 noted it to be the most common in the second year after injury, but presentation later than this may occasionally occur. The occurrence of AVN does not always require intervention. Barnes et al.15 reported that of their cases, 24.3% were asymptomatic, and 46.4% had an acceptable level of disability. This left 29.2% of patients with significant disability and of these 60% underwent further surgery. More recent studies have reported very similar rates of asymptomatic patients who require no surgery.201 
Diagnosis is straightforward in patients with typical radiographic signs of increased femoral head density or collapse. In symptomatic cases, the usual treatment option is conversion to an arthroplasty. For most patients, THA is the best choice since the segmental collapse of the head is often associated with degenerative changes in the acetabulum. Furthermore, many patients now treated with reduction and fixation are young, and the best long-term outcome is probably associated with a modern design of total arthroplasty. If the acetabular surface is well preserved or the patient is elderly with limited functional demands or medical comorbidities then a hemiarthroplasty is a reasonable alternative. 

Prosthesis Dislocation in Femoral Neck Fractures

Dislocation is the most common reason for revision surgery after arthroplasty within 2 years of injury.176 Dislocation rates with unipolar hemiarthroplasty are 2%, rising to 3% following a bipolar hemiarthroplasty. As already indicated, the dislocation rate following THA has been higher than the rate reported for hemiarthroplasty, but the incidence of this complication following THA has declined steadily. Lu-Yao et al.176 quoted a rate of 11% that had declined by the subsequent meta-analysis of Bhandari et al.24 to 6%. In more recent randomized trials evaluating the use of THA for femoral neck fractures, the incidence has been similar. Of 313 patients receiving THR in these trials, there were 25 recorded dislocations, an incidence of 8% (Table 49-4). There may be a number of contributory factors to the decline in reported dislocation rates after THR. There has been a tendency to avoid using implants with small femoral heads such as the Charnley prosthesis with higher dislocation rates. Another factor that may contribute is the availability of more surgeons with specific arthroplasty expertise to carry out the procedure. 
Dislocations have similar causes to those in patients undergoing arthroplasty for osteoarthritis. Technical errors at the time of surgery with implant malposition are perhaps the commonest cause. The surgical approach also has an influence with the posterior approach, having been identified as increasing the risk of dislocation significantly compared with anterolateral exposures.86 Older prostheses such as the uncemented Austin Moore may loosen and change position if the patient is active or has another fall. Finally, patient noncompliance with the usual arthroplasty precautions is more common in this group than in the osteoarthritic patient. 
Closed reduction is usually possible with unipolar and total hip implants. The bipolar hemiarthroplasty is much more difficult to reduce closed although it is usually worth attempting. A particular risk with closed reduction of bipolar implants is dissociation of the bipolar head from the stem, which will make closed reduction impossible. In cases of recurrent dislocation or irreducible dislocation, an open reduction is required. In this situation careful preoperative planning is required. It may be obvious from the preoperative assessment that there is a malposition of the original implant, in which case revision of the prosthesis is likely to be necessary to prevent further episodes of dislocation. 

Prosthetic Loosening and Revision in Femoral Neck Fractures

Prosthetic loosening tends to be a later complication of arthroplasty surgery even in the hip fracture population. Studies with long-term follow-up of these patients are uncommon, and consequently there are limited data on loosening and revision rates. The high early mortality and limited life expectancy and elderly demographics of the population undergoing arthroplasty for femoral neck fractures mean that long-term follow-up is uncommon. Ravikumar and Marsh241 reported mortality rates of 85% and 91%, respectively, for hemiarthroplasty and THR at a 13-year follow-up. 
Eiskjaer and Ostgård81 evaluated the survivorship of hemiarthroplasty. They recorded an overall survivorship of 90% at 5 years and 85% at 10 years. The prostheses studied were the Austin Moore, the Christiansen, and the Hastings. The latter two are bipolar designs. The rate of loosening following unipolar hemiarthroplasty has been higher than following bipolar hemiarthroplasty.312 The risk of loosening following bipolar hemiarthroplasty is low. In five studies reporting this outcome, the revision rate for loosening was 1.6%.20,23,112,122,209 
Data on the long-term outcome of THR are even sparser. Taine and Armour283 reported a 4% revision rate at 4 years. Other studies have yielded more optimistic data. Tarasevicius et al.284 reported a 10-year survival of 92% after THA. Lee et al.165 reported long-term survival at a mean of 8.8 years, with a 5% revision rate for loosening. Mabry et al.178 studied the long-term outcome of THA for femoral neck revision and reported 93% 10-year survival and 76% 20-year survival, results which are comparable with those reported for osteoarthritis. 
Taking into account the high mortality and low functional demands in the majority of these patients, the requirement for late revision due to aseptic loosening is low. Most revision arthroplasties will be needed within the first 2 years for the complication of dislocation and infection. The favorable long-term results of THA in the few studies with sufficient follow-up may reflect a bias in patient selection—the operation is usually considered for fitter patients, who may be expected in general to have a lower risk of early complications and a better prospect of longer term survival. 

Outcomes for Femoral Neck Fractures

Many of the clinical reports on treatment outcome have concentrated on surgical measures of outcomes rather than functional measures. Older studies tend to use fairly crude outcome measures such as pain and level of mobility documented in a rudimentary fashion. 

Pain in Femoral Neck Fractures

In the meta-analysis of 1993, Lu-Yao et al.176 reported that patients had better outcomes following either hemi or THA. Overall, 71% of patients with reduction and fixation had no pain at 2 years compared with 86% of patients following bipolar hemiarthroplasty and 90% of patients with THA. Studies published at that time had insufficient long-term data to document pain after the 2-year postinjury period. An analysis of more recent and larger trials shows a pattern emerging favoring a better functional outcome following modern designs of arthroplasty. Pain at 1 year comparing internal fixation with an uncemented Austin Moore hemiarthroplasty was less with the hemiarthroplasty.29,218 In a three-way comparison of the Austin Moore with fixation and cemented hip replacement, Skinner et al.268 reported a higher incidence of pain at 1 year in the Austin Moore group (12% vs. 27%). However, in trials comparing cemented implants with fixation, pain was significantly less at 4 months and 1 year in the arthroplasty groups.153,154,250,285 

Mobility in Femoral Neck Fractures

As might be expected, patients with undisplaced subcapital fractures tend to regain mobility better than those with displaced fractures. Most patients with undisplaced fractures will return to their previous level of mobility, unless complications supervene. Patients with displaced femoral neck fractures have a less favorable outcome in this respect. Poor prognostic factors for return of mobility are increasing age, cognitive impairment, and any degree of impaired mobility before fracture. The choice of treatment will also influence mobility restoration. Some trials comparing fixation with arthroplasty for displaced fractures have shown superior levels of mobility for patients in the arthroplasty groups. This probably reflects the high rate of early complications in patients treated with reduction and fixation. This consideration must be set against the relatively short-term follow-up in many of these trials, which may bias assessment in favor of arthroplasty. However, one would expect with a 2-year follow-up, which is a feature of more recent and larger trials that the effect of early complications in the fixation group might dissipate. This is the case and overall the proportion of patients regaining their previous level of mobility following fixation or arthroplasty is 46%.141,218,250,268,285 Even in these trials mobility was still poorer in the fixation groups at 2 years. In a longer term follow-up of arthroplasty versus fixation, Blomfeldt et al.30 did not demonstrate any improved mobility in the fixation group. 
Comparisons of mobility between total and hemiarthroplasty have tended to indicate better levels of mobility with the THA group. The reasons for this are unclear and may be multifactorial. More clinical data are needed. The reduction in mobility no doubt contributes to the fact that between 15% and 20% of patients will not return to their previous residence.141,218 

Economic Outcome in Femoral Neck Fractures

Studies incorporating or exclusively concerned with economic aspects of treatment are few. Iorio et al.138 reviewed the literature and carried out a cost-effectiveness analysis based on reported outcomes. They predicted that arthroplasty would be more cost-effective than reduction and fixation. The studies that have incorporated an assessment of the economic cost of treatment modalities have tended to analyze and compare the hospital costs of fixation or arthroplasty. Soreide et al.272 found bipolar hemiarthroplasty to be 1.6 times more expensive than fixation, and Johansson et al.143 found no difference in cost between fixation and THR. These findings differ from other published work, which has generally shown fixation to be the more expensive option. Parker et al.218 found three AO screws to be more expensive than the uncemented Austin Moore hemiarthroplasty. Two randomized trials have been published, which incorporated an economic analysis. Rogmark et al.251 reported that arthroplasty (total or hemi) was more cost-effective than reduction and fixation. Keating et al.153,154 compared the costs of THA with cemented bipolar hemiarthroplasty and fixation. Over a 2-year follow-up period, THA was the most cost-effective procedure. The poor economic performance of fixation against arthroplasty in these studies is explained by the high rate and cost of revision surgery in this group. Although the implant costs associated with reduction and fixation are clearly less, the main burden of expenditure in these patients is accounted for by the duration of hospital stay, which has not been found to be any shorter for reduction and fixation compared with arthroplasty. The costs associated with high readmission rates for revision surgery heavily outweigh any financial advantage of the lower implant cost. Although these findings might seem counterintuitive at first, it should be borne in mind that in these patients the main cost driver is the duration in hospital rather the implant costs, which represent a small percentage of the overall cost of treatment. The reason that fixation has been shown to be more expensive in more detailed studies is that the cost is driven up in this group by the high requirement for revision surgery and subsequent readmission. 

Summary, Controversies, and Future Directions in Femoral Neck Fractures

Recent epidemiologic studies indicate that the inexorable rise in the incidence of these fractures may be reaching a plateau or even declining. However, there is no doubt that they will continue to form a considerable component of the orthopedic trauma workload for the foreseeable future. 
Formerly the main controversy in management of these fractures was centered on the debate of fixation versus arthroplasty. Since the publication of the last edition of this book, there has been a gradual move within the orthopedic community toward the use of arthroplasty for a greater proportion of these patients. Fixation will probably always have a role in treatment of these fractures, and it remains the treatment of choice for younger patients with displaced fractures and for any patient with an undisplaced fracture who is fit for surgery. The optimum arthroplasty choice remains a source of debate. The bipolar hemiarthroplasty is probably the most commonly used and popular choice, but there is no evidence that it is superior to a unipolar implant. Its continued popularity is probably explained by the appeal of modularity for the operating surgeon. 
More data are needed to determine whether wider use of THA is justified, as seems to be the case based on recent comparative trials. There has been widespread use of old and outmoded uncemented arthroplasties for these fractures. This may account for the evidence supporting the use of cemented rather than uncemented stems in these patients. Trials providing information on the results of newer designs of modern uncemented prostheses can be expected and may support their use, but the results may not be comparable to their use in osteoarthritic patients particularly as the majority of patients with intracapsular fractures have osteoporosis and wide femoral medullary canals, which may not be the ideal host bone for use with uncemented stems. Now that arthroplasty is established as the preferred treatment method for the majority of these patients, clinical research is required to provide evidence on the arthroplasty choices associated with the best functional outcome and lowest economic tariff and surgical comorbidity. 

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