Femoral Neck Fractures

0030–5898/02 $15.00 + .00

TREATMENT OF COMPLEX FRACTURES

FEMORAL NECK FRACTURES Andrew H. Schmidt, MD, and Marc F. Swiontkowski, MD

Femoral neck fractures remain a vexing clinical problem for orthopedic surgeons. Attempting to salvage the femoral neck often leads to healing complications, while the more predictable operation (prosthetic replacement) is associated with poorer function and has significant complications of its own. Added to this dilemma is the high mortality rate of patients in the age group that most often sustains these fractures. The orthopedic literature is replete with case studies and retrospective comparative trials on the treatment of femoral neck fractures, but the quality of evidence that we have to guide us is poor. Lu-Yao et al51 attempted to perform a meta-analysis of the outcome of displaced femoral neck fractures. Nonunion was twice as common as osteonecrosis (33% and 16%, respectively). Although reoperation was more common after internal fixation than after prosthetic replacement, the investigators were not able to draw any statistically valid conclusions about the factors that affect the outcome of femoral neck fractures. EPIDEMIOLOGY The incidence of femoral neck fracture is increasing dramatically as the mean age of the population increases.68 The number of hip fractures in the United States doubled from the mid-1960s to the 1980s. It has been predicted that by 2050, the number of hip frac-

tures would triple.27 As a consequence, proximal femur fractures are a significant cause of morbidity and mortality in all age groups, especially in the elderly. At the present time, more than 250,000 hip fractures occur in the United States each year, with associated health care costs of $8.7 billion.66 Extensive debate continues over the cost-effectiveness of various medical and surgical therapies, including the treatment of fractures of the hip. Using the concept of quality-adjusted life years, Parker et al64 determined that operative treatment was cost-effective for displaced intracapsular and all extracapsular fractures of the hip. The proper care of hip fractures is important not only for the continued health and vitality of our population but also for the health of our economy. Femoral neck fractures occur most commonly in the elderly patient after a seemingly minor fall or twisting injury and are more common among women.66 Numerous factors are related to the high incidence of hip fractures in the elderly population, including osteoporosis, malnutrition, decreased physical activity, impaired vision, neurologic disease, poor balance, altered reflexes, and muscle atrophy. Chronically ill elderly patients have an increased risk for infection and other systemic complications after fracture despite appropriate medical and surgical management. Osteoporosis remains the most important contributing factor to hip fractures,

From the Department of Orthopaedic Surgery, University of Minnesota (AHS, MFS) and Hennepin County Medical Center (AHS), Minneapolis, Minnesota

ORTHOPEDIC CLINICS OF NORTH AMERICA VOLUME 33 • NUMBER 1 • JANUARY 2002

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and its incidence has been well documented with respect to age-, race-, and sex-matched controls.48, 50, 56, 75, 79 The absolute rate of hip fracture is highest for white women, followed by white men, black women, and black men.38 These differences in incidence are thought to reflect the difference in bone density, which is greater in blacks than in whites. Alffram1 reported that patients with intertrochanteric fractures are slightly older and have higher morbidity and mortality rates than do those with femoral neck fractures. Femoral neck fractures also occur in the young but less frequently. In the young, these fractures are usually the result of high-energy trauma and often are associated with other injuries. In the young, hip fractures are more common in males, who are also more prone to trauma. BIOLOGICAL AND MECHANICAL CONSIDERATIONS Most of the vascular supply to the femoral head originates from the medial and lateral femoral circumflex arteries, which form an extracapsular ring around the femoral neck. Ascending cervical branches pass the femoral neck proximally and enter the capsule at its insertion. Fractures of the femoral neck may disrupt the vascularity of the femoral head18, 69, 70 ; however, displaced fractures of the femoral head can occur without disruption of the medial femoral circumflex or lateral epiphyseal systems.22 Therefore, urgent anatomic reduction and internal fixation of displaced femoral neck fractures is advocated to restore blood flow in vessels that may be kinked by the displaced fragments. Rarely, collateral circulation can maintain the viability of the femoral head when the primary vessels are disrupted.70 The bony anatomy of the upper end of the femur is extremely important because it determines where internal fixation devices should be implanted for maximum purchase in the femoral head (Fig. 1). With increasing age, the cortex of the femoral neck thins and cancellous trabeculae are resorbed, significantly weakening the proximal femur.71 This increases the risk for fracture with loading and makes internal fixation more prone to failure. Study of the trabecular pattern allows surgeons to estimate the degree of osteoporosis and the likelihood of successful internal fixation, although the subjectivity of evaluating

Figure 1. A healed femoral neck fracture, showing ideal screw placement in the center of the femoral head, at the convergence of the tension and compression trabeculae.

these patterns has made its use unreliable44 (Fig. 2). The two major forces acting on the hip joint are abductor muscles and body weight, as defined by the joint reaction force. In men, the normal joint reaction forces can be as much as four- to sevenfold body weight, and in women, 2.5- to fourfold body weight.60 Stair climbing causes maximum hip forces of up to sevenfold body weight.25 The use of a bedpan produces forces on the hip equivalent to walking with the use of external supports.60 Nordin and Frankel60 showed with instrumented nailplate implants that only one fourth of the total load is borne by the fixation device if bone fragments are allowed to impact. Implants designed for fracture fixation must withstand extremely high loads and bending moments. Fortunately, many studies have shown that full weight-bearing is not detrimental if stable internal fixation is achieved.45 This is important because mobilization of the patient is important to avoid systemic complications. Even after fracture union, the risks for osteonecrosis and arthrosis remain. If these late complications ensue, the patient is subject to further costs and the hazards of secondary intervention.

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Figure 2. A failed attempt to repair a femoral neck fracture with screws. Careful study of the preoperative radiograph (A) shows that there are no bone trabeculae within the femoral neck causing the screw fixation to fail (B).

CLASSIFICATION The Garden classification of femoral neck fractures remains in wide use.29, 32, 67 The Garden classification is based on the amount of fracture displacement evident on anteroposterior (AP) radiography of the hip, although surgeons must be aware that significant displacement may be apparent on lateral radiography and not seen on AP radiography. The grades correlate with the prognosis for healing and the rates of avascular necrosis or nonunion. Garden I and II fractures are nondisplaced. Garden III and IV fractures are displaced and have a worse prognosis for healing and osteonecrosis. Recently, it has been shown that the inter- and intraobserver reliability of the Garden classification is poor 86 ; however, agreement was improved when fractures were grouped into either undisplaced (stage I and II) or displaced (stage III and IV) classes.86 An alternative way to classify femoral neck fractures is based on the angle of the fracture line with the horizontal plane.63 More vertical fractures have higher shear forces across the femoral neck and may have a greater potential for hardware failure; however, recent retrospective reviews have failed to confirm that the fracture angle is of any value for predicting the risk for fixation failure.63 In addition to displacement, the rotation of the femoral head must be evaluated to give the

surgeon the best estimate of the severity and the comminution of the fracture. Rotational moments are a significant part of the normal loading of the hip, and resistance to rotation is an important factor in fracture stability. Posterior comminution increases the potential for rotational and varus instability (Fig. 3). Rotational malignment is present when the major compressive trabeculae in the femoral head do not accurately align themselves despite overall good alignment of cortical shells. TREATMENT The treatment of femoral neck fracture depends primarily on the age and activity of the patient, the severity of fracture displacement, the age of the fracture, and the degree of osteoporosis present. Elderly patients with medical comorbidities should have their condition optimized.43 The optimum timing of internal fixation of femoral neck fractures remains controversial.65 It has been suggested that the incidences of avascular necrosis and nonunion are decreased by fixation within 6 hours after injury 53 ; however, some studies have not shown an increase in the rate of osteonecrosis or nonunion with delayed fixation of up to 1 week. Because of the biological advantages, the authors perform stabilization

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Figure 3. Posterior comminution of the femoral neck, with posterior angulation, impaction, and malrotation.

of the fracture as soon as the patient has been evaluated medically and is stable. For undisplaced fractures, in situ fixation is advisable because the risk for displacement with nonoperative treatment is as high as 20%.26 Displaced femoral neck fractures are treated according to the age and functional demands of the patient. Patients with these fractures are at high risk for avascular necrosis and nonunion, averaging 30% and 15%, respectively.33, 51, 67, 82 In healthy, active patients, the treatment of choice is reduction and internal fixation. An anatomic reduction must be obtained for a good result. Femoral neck fractures reduced anatomically are best fixed with three pins or screws.83 A closed reduction may suffice, but the capsule should be opened to decompress the hemarthrosis that may impair head perfusion. If a satisfactory closed reduction is not achieved, an open reduction is indicated. One should avoid repeated attempts at performing closed reduction maneuvers because repeated manipulations may cause additional trauma and potential vascular insult. The most important factor leading to success in the treatment of the young patient with a femoral neck fracture is immediate anatomic reduction with stable internal fixation. In the series from the Orthopedic Trauma Hospital Association,46 multiple screws seemed to be the best choice for fixation, with complications that include 13% with

avascular necrosis and nonunion in 14%. In contrast, the use of hip compression screws led to 50% avascular necrosis and 40% nonunions. Malreduction with varus angulation resulted in 60% avascular necrosis and 40% nonunion. Ten degrees or more of anterior or posterior angulation also led to increased complications. Muscle pedicle grafting was of no benefit in preventing either avascular necrosis or nonunion and was associated with a 13% infection rate. Swiontkowski et al82 reported avascular necrosis in 19% and no nonunions in a smaller series of young patients with femoral neck fractures treated with multiple screws. Inactive or chronically ill patients may be considered for primary prosthetic replacement to avoid the complications from loss of fixation or osteonecrosis. A prosthetic replacement also may be desired in a patient with hip arthritis in conjunction with a femoral neck fracture. CLOSED REDUCTION OF FEMORAL NECK FRACTURES Closed reduction of the femoral neck is performed with the patient under general anesthesia using image intensification. In general, a simple combination of traction in extension and gentle internal rotation is all that is necessary. Alternatively, Leadbetter’s maneuver

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may be performed and involves reducing the femoral neck in flexion. First, the hip is flexed 90◦ and the thigh is rotated internally. With traction applied in line with the femur and while internal rotation is maintained, the limb is then circumducted into an abducted position and then brought into extension. If closed reduction is successfully achieved, one may proceed with internal fixation. Release of the capsule should be performed at the same time to decompress the joint and relieve possible intra-articular tamponade.78, 84 INTERNAL FIXATION OF THE FEMORAL NECK Placement of multiple screws across the fractured femoral neck is the treatment of choice and may be performed following either closed or open reduction using a standard lateral approach or a more limited percutaneous technique. Many types of screws are available, including solid or cannulated screws made from either stainless steel or titanium. Good results are to be expected following fixation of nondisplaced femoral neck fractures. The outcome after fixation of displaced fractures is less predictable, and the management of displaced fractures is more controversial. Swiontkowski and Hansen80 reported on the results of percutaneous pinning of femoral neck fractures in 32 medically debilitated patients. Technical complications occurred only in the group with displaced fractures, none of whom regained functional ambulation. In contrast, 92% of the patients with nondisplaced or impacted fractures were ambulatory at 2-year follow-up. To minimize complications, pins or screws should be placed within the central two thirds of the femoral head.59 The authors aim for central screw placement, with the tip of the screw no closer than 5 mm to subchondral bone. The authors recommend that one inferior screw should be placed along the medial femoral neck, with two more proximal screws placed in a triangular configuration both anteriorly and posteriorly in the femoral neck (Fig. 4). Placing the screws adjacent to the cortex of the femoral neck may improve stability.13 The inferior screw must exit the lateral femoral cortex at or above the lesser trochanter. The authors have seen subsequent subtrochanteric fracture at the distal screw when it is placed distal to the lesser trochanter. Using the “three-point principle,” with screws placed adjacent to the inferior and posterior cortices,

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B Figure 4. A and B, Correct screw placement, with the screws against the inferior and posterior cortices, and within 5 mm of subchondral bone in the center of the femoral head.

Bout et al14 achieved union in 35 of 40 displaced femoral neck fractures. Four of the five failures were associated with clear faults in the operative technique.14 Imperfect fracture reductions may prevent reestablishment of the blood supply to the femoral head and decrease the amount of bony apposition at the fracture, causing poor mechanical stability after fixation. Garden31 showed that valgus reduction of more than 20◦ is associated with higher rates of avascular necrosis. Any amount of varus deformity after reduction is associated with increased rates of avascular necrosis and nonunion.46 AP angulation of more than 10◦ should not be accepted, particularly in osteoporotic bone, because of the potential for further displacement. On lateral radiography, surgeons should pay particular attention to

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the degree of posterior comminution. Both Garden and Banks have shown that fractures with marked posterior comminution have a high incidence of nonunion.8, 30, 32 In a study using cadaveric femora with simulated posterior comminution, fractures fixed with four screws were significantly stronger than were those repaired with three screws.42 In cadaver bone, the use of a calcium–phosphate cement dramatically improved the load to failure of femoral neck fractures fixed by three 7-mm cannulated screws.74 If closed reduction within acceptable limits cannot be obtained, the surgeon should proceed to open reduction, which affords surgeons several advantages. First, it decompresses the hip. Second, it is the best way to ensure appropriate rotational alignment of the femoral head. Finally, drilling of the femoral head may allow surgeons to assess the viability of the femoral head.34 Open reduction may be performed by extending the lateral incision and using the interval between the tensor fascia lata and gluteus medius (Watson-Jones approach) or by an anterior approach. In the latter case, a separate incision may be necessary for screw placement. If the patient is a candidate for arthroplasty and the surgeon is unwilling or unable to perform an adequate open reduction, the treatment plan for reduction and fixation may be abandoned and the surgeon may proceed with prosthetic replacement. SLIDING HIP SCREWS Many experts advocate the use of a sliding hip screw for the fixation of basicervical fractures (Fig. 5).10 In a biomechanical study, a sliding hip screw with or without a derotation screw was stronger than three cannulated screws in axial loading10 ; however, a clinical study found that the union rate of displaced femoral neck fractures was higher after fixation with four cancellous screws than with a sliding screw plate.52 Sliding hip screws provide improved fixation of vertically oriented fractures,4 and these devices should be considered in the treatment of such fractures. PROSTHETIC REPLACEMENT Prosthetic replacement of the displaced femoral neck fracture is advocated by some because of the high rates of nonunion and

avascular necrosis; however, the relative merits of attempting fixation versus performing arthroplasty are controversial. In one study of more than 500 femoral neck fractures treated with internal fixation, 79% of the patients retained their femoral head and 67% required only one operation.57 The incidence of reoperation was actually lower among the patients over age 70 years than among younger patients. Other studies have found arthroplasty to be associated with lower complication rates than internal fixation.39 Gerber et al33 found that local complications predominated after internal fixation, whereas systemic complications were more common after hemiarthroplasty. Bogoch et al12 reported that internal fixation of displaced femoral neck fractures in patients with rheumatoid arthritis failed in 64%, whereas primary total hip replacement was successful in 95%. Carpenter et al17 found that the reoperation rate following internal fixation was much higher (28%) than that following either unipolar (5%) or bipolar (3%) arthroplasty. In general, it is best to salvage the femoral head whenever possible. The use of a study implant that maintains a valgus neck-shaft angle, controls potential rotation, and allows for controlled compression of the fracture; it provides the best results with minimal complications. In older and less active patients with displaced femoral neck fractures, hemiarthroplasty seems to be the optimum management. Bray et al15 performed a prospective, randomized comparison of bipolar hemiarthroplasty to internal fixation. Fewer complications and better function at 2-year follow-up were found in the hemiarthroplasty-treated group. Options for prosthetic replacement include unipolar hemiarthroplasty, bipolar hemiarthroplasty, and total hip arthroplasty. Cemented or uncemented devices may be used. Early unipolar devices were found to have frequent complications, including disabling pain and acetabular erosion.41 Bipolar hemiarthroplasty was developed in hopes of lessening this complication, but clinical reports suggest that measurable acetabular erosion still occurs.11, 47 Nevertheless, clinical studies comparing unipolar with bipolar prostheses suggest better results with the latter devices.61 Other potential complications include stem loosening, dislocation, femoral shaft perforation, periprosthetic fracture, and infection. Total hip replacement provides the best results of any form of prosthetic replacement

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D Figure 5. A and B, A basicervical fracture treated with a sliding hip screw and single derotation screw (C and D).

for displaced femoral neck fracture; however, several investigators have found that dislocation after hip arthroplasty for fracture is more common than after operations for arthritis.35, 86 In 50 patients equally divided between fractures and arthritics, the hip range of motion was significantly greater among those

undergoing surgery for fractures.35 This increased movement is thought to be a predisposing factor for dislocation in patients managed with hip arthroplasty for femoral neck fractures. Total hip arthroplasty after a displaced femoral neck fracture should be reserved for patients with preexisting arthritis

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or for very high-demand patients in whom internal fixation is not possible or has failed. COMPLICATIONS Loss of Fixation Implants that are used for internal fixation of the proximal femur can fail because of the large bending loads that are present in the proximal femur and the poor bone quality that is usually associated with fracture. Many displaced fractures are unstable and have posterior and medial comminution with loss of a stable medial buttress. The implant may cut out of the superior femoral neck as the fracture settles into varus displacement; break at the site of the fracture; or, in the case of a sideplate device, pull out from the femoral shaft

(see Fig. 2). Technical problems that may lead to failure include poor screw position, placement of screws with threads that cross the fracture site, and imperfect fracture reduction. Failure of internal fixation of a femoral neck fracture with either multiple pins of a sliding hip screw is most dependent on bone quality and screw placement.24, 87 Swiontkowski et al83 found no benefit to using more than three pins and that bone density is a useful predictor of the success of fixation. The treatment of failed osteosynthesis of the femoral neck depends on the timing and mode of failure and the patient’s general condition and activity level. Repeat fixation may be considered in younger or more active patients if the bone stock is adequate. Often, a valgus osteotomy with blade plate fixation is necessary to restore the correct mechanical axis of the femoral neck (Fig. 6). Conversion

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D Figure 6. A femoral neck nonunion (A), confirmed by CT scan (B). Union was achieved after valgus osteotomy and blade plate fixation (C and D). (Courtesy of David Templeman, MD, Minneapolis, MN.)

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to an arthroplasty is needed if osteonecrosis ensues or because of poor bone quality. Longstem devices should be used to ensure that the tip of the stem is distal to the screw holes in the lateral femoral cortex (Fig. 7). Franz´en et al28 found that the results of total hip arthroplasty for failed fixation of femoral neck fractures was age dependent. Patients aged more than 70 years who underwent primary hip replacement after fracture had a fivefold risk for prosthetic failure compared with agematched patients undergoing hip replacement for osteoarthritis. Nonunion Delayed or nonunion of a femoral neck fracture often is manifested by continued pain with weight-bearing beyond 3 months after fixation. Nonunion of femoral neck fractures has a reported incidence from 2% to 22% and generally becomes apparent within 1 year.2, 7, 8, 19 The risk for nonunion is greater with displaced fractures and has been reported to be as high as 30% in some series.21, 62, 66, 72

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The variability in the incidence of nonunion in different series of cases may be explained by differences in patients, fracture type and by the investigators’ method of reduction and fixation technique.62 Madsen et al52 found that the union rate of displaced femoral neck fractures was higher after fixation with four cancellous screws (84%) than with a sliding screw plate (64%). Nonunion is associated with pin migration.54 Furthermore, nonunion and pin migration occurred only in the displaced fracture patterns. Valgus reduction seemed to protect against pin migration.54 Hammer 37 reviewed 141 patients following osteosynthesis of a femoral neck fracture with 6.5-mm AO screws. The rate of nonunion was correlated with the Garden classification and was 1% for Garden I fractures and over 25% in Garden III and IV fractures. Irrespective of the Garden classification, a vertical fracture orientation resulted in a 40% rate of nonunion.37 Parker 62 found that the best predictor of nonunion was patient age and preoperative fracture displacement. Nonunion may be accompanied by avascular necrosis. If nonunion occurs, the surgeon

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B Figure 7. A total hip performed for a failed proximal femur fracture treated with a sliding hip screw. Two screw holes are present in the femoral shaft below the tip of the prosthesis (A). A displaced periprosthetic fracture occurred within 2 weeks after surgery (B).

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should use MR imaging to evaluate vascular supply to the femoral head before continuing with treatment options. Fixation of the femoral neck with titanium screws aids in accuracy of MR imaging interpretation by minimizing scatter of the image that occurs with the use of stainless steel screws. MR imaging has largely supplanted scintigraphy in the evaluation of femoral head viability. Options for the treatment of nonunion include repeat internal fixation, bone or musclepedicle grafting, valgus osteotomy, and hip arthroplasty. In active patients, nonunion is treated with a valgus osteotomy and repeat fixation. Marti et al55 reported a series of 50 patients aged less than 70 years who underwent valgus osteotomy for ununited femoral neck fractures. Six cases required reoperation because of technical complications. Seven hips underwent later replacement: three hips for persistent nonunion, three hips for severe osteonecrosis, and one hip for hardware breakage. The remaining 43 fractures had 7 years’ average follow-up. Although avascular necrosis was evident in 22, only 3 patients had symptoms suffiently severe to require arthroplasty. In a series of 17 patients, union was achieved in all but one after osteotomy.6 Five patients required an additional operation. Although the operation is difficult, this study recommends osteotomy in younger, active patients with nonunion of the femoral neck.6, 55 Only smaller series have reported on the use of a posterior muscle pedicle graft and bone graft as an adjunct to internal fixation of a femoral neck nonunion.5 The success of this treatment is difficult to assess because the series report a limited experience. Most nonunions have drifted into some varus angulation, and a valgus osteotomy and fixation are essential to apply compression loads at the fracture site and promote healing. Therefore, the best option is an intertrochanteric osteotomy with realignment of the proximal femur into valgus if salvage of the femoral head is warranted. In some instances, such as if severe osteonecrosis is present or in elderly community ambulators, nonunion may be treated best by total hip replacement. Unfortunately, no comparative studies are available to aid clinicians in decision making for this complex problem. Avascular Necrosis The lateral epiphyseal artery supplies most of the femoral head circulation. This vessel is

at considerable risk of lacuation or kinking after femoral neck fracture; it runs in the superior capsule, which frequently is disrupted by such fractures, especially when displaced. Most clinically relevant avascular necrosis follows displaced intracapsular fractures. Most studies report osteonecrosis rates in displaced femoral neck fractures of 10% to 20%.33, 51, 82 Differences may be explained by the fracture type and by the investigators’ method of reduction and fixation. Stromqvist et al76, 77 examined the use of scintigraphy to assess the viability of the femoral head after femoral neck fracture. Decreased radionuclide uptake within the first 2 weeks of injury is 91% predictive of healing complications.77 Furthermore, decreased uptake is found in some fractures preoperatively; these patients invariably experience healing complications.76 In other patients, deficient uptake is seen only postoperatively, indicating that perioperative factors (e.g., intra-articular tamponade, traction, of reduction maneuvers, also influence the development of osteonecrosis. Patients with normal uptake 2 weeks after injury are unlikely to develop osteonecrosis.77 The risk for avascular necrosis is proportionate to the degree of displacement and the time to reduction. Operation within 6 hours of injury leads to improved union rates and a decreased incidence of femoral head collapse.53 Late-onset avascular necrosis is manifested by bone sclerosis, subchondral collapse and, eventually, secondary degenerative changes of the hip. In the early stages of symptoms, radiographic findings are normal. MR imaging provides the most sensitive and specific means of identifying avascular necrosis in the early stages, when treatment may be beneficial; however, MR imaging performed at the time of injury is unable to predict which intracapsular fractures will develop clinical avascular necrosis.3, 73 Furthermore, treatment should not be based on the results of MR imaging alone; the severity of clinical symptoms, the degree of femoral head collapse, and the amount of degenerative change on radiographs are more important clinical factors. Surgeons can minimize the risk for osteonecrosis in several ways. Urgent reduction and fixation may be the most important. Several investigators have shown that intracapsular fractures of the proximal femur result in markedly elevated intracapsular pressures secondary to hematoma formation.24, 40, 78 Using laser Doppler flowmetry, Swiontkowski, et al84 showed significant diminution of femoral

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head blood flow with elevated intracapsular pressures in an animal model. Crawfurd et al24 used ultrasonography to show capsular distension following both nondisplaced and displaced femoral neck fractures and documented elevated intracapsular pressures associated with joint hemarthrosis. Some displaced fractures showed evidence of capsular disruption with extracapsular hematoma; this subgroup of hips had low pressures consistent with decompression of the hip. Capsulotomy is recommended to relieve the intracapsular hematoma and restore blood flow.24, 84 Stromqvist et al78 showed that the intracapsular pressure is highest with the leg internally rotated and lowest in a position of mild flexion and external rotation. These workers also demonstrated, that following hip aspiration, intracapsular pressures decreased to zero, and scintigraphic uptake increased in most hips, consistent with improved blood flow. Although the need for capsulotomy in femoral neck fracture remains controversial, it is so simple to perform that it should be recommended. Another benefit of capsulotomy is that it allows for direct visualization of the femoral head and its capacity to bleed. Gill et al34 drilled a 2-mm hole into the femoral head fragment at surgery; none of 56 patients with bleeding from the drill hole developed avascular necrosis at 2 years of follow-up or more. In contrast, all 8 patients without bleeding developed avascular necrosis. Intraoperative drilling may be the best method to assess the risk for avascular necrosis, although longer-term follow-up is needed. The treatment of avascular necrosis remains controversial. Often, osteonecrosis does not involve the entire femoral head. In many cases, collapse of the head does not occur. If the patient is asymptomatic, no further treatment is indicated. If collapse of the osteonecrotic fragment has occurred and the patient is symptomatic, then surgical treatment may be indicated. The degree of involvement on imaging studies does not necessarily correlate with the severity of symptoms. In general, young, active patients are more disabled by avascular necrosis than are sedentary patients. Treatment options are based on age, activity level, and severity of symptoms and include core decompression, proximal femoral osteotomy, arthrodesis, and prosthetic replacement. Core decompression may be performed in painful lesions that have not collapsed. In younger patients or those with well-circumscribed lesions, osteotomy is ap-

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propriate. Although arthrodesis is more difficult because of the avascular bone, it may be considered for younger patients with more severe involvement that precludes osteotomy. For the management of severe osteonecrosis in the older patients, total hip arthroplasty is recommended. Whether cemented or uncemented implants are better is unknown; surgeons should select whatever technique and implant they are most familiar with. Hemiarthroplasty is performed in elderly patients with minimal functional demands. FEMORAL NECK FRACTURES IN CHILDREN Children rarely sustain fractures near the hip; when they occur, they are often the result of high-energy trauma. Multiple injuries are present in half of these cases, and these patients traditionally are considered to have a poor prognosis. Potential complications include osteonecrosis, nonunion, coxa vara, and premature physeal closure with trochanteric overgrowth and leg-length inequality.16 Twenty percent of cases are associated with ipsilateral femoral shaft fractures. Complication rates are proportional to the initial degree of displacement,16 and studies that have followed up patients into adulthood have shown that the initial results deteriorate significantly with time.49 Delbet20, 58 has classified these fractures into four types: type I, transepiphyseal; type II, transcervical; type III, cervicotrochanteric; and type IV, intertrochanteric. Proximal femur fractures involving the growth plate (type I) are reported to result in avascular necrosis and premature physeal closure in 80% to 100% of patients.16 Early hip decompression in type I injuries does not affect the incidence of avascular necrosis, suggesting that the vessels are disrupted.58 Nevertheless, the best results of treatment overall have been with immediate decompression of the joint by capsulotomy and rigid internal fixation.20, 58 Despite the lack of documented efficacy, decompression of type I fractures still should be attempted. Early hip decompression seems to decrease the risk for avascular necrosis in type II and III fractures and should be performed in all such cases.20, 58, 81 In one series, hip capsulotomy reduced the rate of avascular necrosis in type II and III fractures from 41% to 8%.58 Cheng and Tang 20 had no cases of avascular necrosis in a series of 14 patients with a mean follow-up

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of almost 5 years. These investigators performed hip aspiration, closed reduction, and internal fixation within 24 hours of injury. By using an aggressive operative approach with early open reduction, capsulotomy, and compression screw fixation, Swiontkowski and Winquist 81 reported good results in eight patients with 2-year follow-up. One patient had a type I (transepiphyseal) fracture in their series; this patient developed radiographic evidence of partial avascular necrosis of the femoral head but was asymptomatic at the 2-year follow-up examination. Immediate anatomic reduction and screw fixation are recommended for all children with fractures of the proximal femur, except for there with undisplaced basilar neck fractures or fractures in the intertrochanteric region (type IV), which may be treated by spica casting.81 As in fractures in adults, hip decompression should be performed in all femoral neck fractures in children.81

COMBINED FRACTURES OF THE FEMORAL NECK AND SHAFT Ipsilateral fractures of the femoral neck and shaft are uncommon and challenging injuries that typically occur in multitrauma patients. Often, the femoral neck fracture is not recognized at the time that the shaft fracture is treated.88 In a review of the literature, Bennett et al9 reported that the incidence of delayed diagnosis was 31%. The associated femoral shaft fracture often is comminuted or open and usually occurs in the proximal to middle third of the femur.88 In contrast, the femoral neck fracture usually is minimally displaced and is typically extracapsular, which may contribute to the difficulty in diagnosis. The injury of primary importance in this fracture complex is the femoral neck fracture. Most surgeons recommend immediate reduction and stabilization of the femoral neck fracture with compression screws, followed by subsequent stabilization of the femoral shaft fracture.88 In unstable multitrauma patients, a delay in fixation of several days to weeks should not preclude fixation because the complication rate does not seem to be increased.88 One possible choice for fixation is a secondgeneration interlocking nail, which may be used to stabilize both the femoral neck and shaft fractures; however, this technique may

compromise the reduction and fixation of the femoral neck and may lead to complications. Poor results have been reported with the reconstruction nail, with complications in as many as 75% of cases in one series.88 Another option is antegrade nailing of the shaft, with supplemental screw fixation of the neck. In this circumstance, two additional lag screws are placed anterior to the nail. As mentioned earlier, it is of paramount importance to avoid displacing the femoral neck fracture when this technique is used. An acceptable alternative is routine stabilization and fixation of the femoral neck fracture with multiple screws, followed by plating or retrograde nailing of the femoral shaft (Fig. 8). Avascular necrosis seems to be less common in cases of ipsilateral neck and shaft fractures than of isolated neck fractures.9 Occasionally, the femoral neck fracture is not identified until after, or may occur during, intramedullary nailing of a diaphyseal fracture. This also calls for emergent reduction and stabilization of the femoral neck, and multiple cancellous lag screws generally can be placed around the proximal femoral nail. Higher rates of osteonecrosis and nonunion should be expected in these situations.88 THE FUTURE TREATMENT OF FEMORAL NECK FRACTURES Future advances in the surgical management of femoral neck fractures depend on an improvement in the methods of orthopedic research and advances in the management of osteoporosis. Certainly, as physicians learn of the results of well-designed randomized prospective trials, treatment will become evidence based rather than anecdotal. In addition, it is likely that physicians will have better methods to manage one of the biggest problems in the fixation of femoral neck fractures, namely, poor bone quality. The medical management of osteoporosis is improving, and the incidence of osteoporosis will be less in the future. In addition, fracture comminution likely will be managed by augmenting the bone with some sort of injectable bone graft substitute. Specifically, augmentation with calcium–phosphate cement has been shown to improve significantly the strength and stiffness of fixation in cadaveric bone fixed with screws.36, 74 Clinical pilot studies of this technique are in progress.36

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A

C Figure 8. An ipsilateral femoral neck and shaft fracture. The radiograph clearly shows both fractures (A). The patient underwent closed reduction and screw fixation of the femoral neck, followed by retrograde nailing of the femoral shaft (B and C).

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