Fractures of the Femur

I. FRACTURES OF THE FEMORAL NECK

A. Epidemiology. Despite predictions of an alarming increase in the incidence of hip fractures due to the aging of the population, recent evidence suggests that the per capita, age-adjusted incidence and mortality of these injuries have been decreasing since 1995 in the United States¹ and 1985 in Canada.² Femoral neck fractures account for just over half of all proximal femoral fractures and are most common in patients older than 50 years; elderly patients account for approximately 95% of the total number of cases.^3,4 These fractures become more common with increasing age because of the combination of osteoporosis and an increasing propensity for falls. Besides osteoporosis, other factors associated with an increased risk of femoral neck fracture are early menopause (or low estrogen state), alcoholism, smoking, low body weight, steroid therapy, history of stroke, phenytoin treatment, and lack of exercise. Excessive use of sedative drugs has also been implicated.⁵ Typical patients are female, fair, and thin. Efforts at preventing falls in elderly persons seem to have the most potential for controlling this phenomenon. Trochanteric pads may lessen the risk of fracture with falls,⁶ but compliance is poor and their usefulness has been questioned.⁷ In the elderly, hip fractures result in an increased 1-year mortality rate of 12% to 18%.

Femoral neck fractures in younger patients usually result from high-energy trauma. In addition to traumatic injuries, stress fractures of the femoral neck may occur in active patients. Stress fractures that occur along the superior aspect of the femoral neck are called tension fractures and have a high propensity to progress to complete fractures. The compression stress fracture, which occurs at the base of the femoral neck, is less likely to displace.

B. Classification of fractures. From the clinical standpoint, femoral neck fractures consist of four basic types: displaced, nondisplaced, impacted, and the stress fractures. Recent papers have highlighted the vertical femoral neck fracture, referred to as a Pauwels Type III, as having higher complication rates including a 14% nonunion rate in cases with adequate reduction.⁸ Radiographs readily distinguish these patterns, although some nondisplaced fractures may be radiographically occult and are only diagnosed after magnetic resonance imaging (MRI). Approximately two-thirds of femoral neck fractures are displaced.⁴

C. Symptoms and signs of injury. Patients with stress fractures, nondisplaced fractures, or impacted fractures may complain only of pain in the groin or sometimes pain in the ipsilateral knee. Patients with stress fractures often have a history of a recent increase in activity and may believe themselves to have a “groin” strain. In contrast, patients with nondisplaced or impacted fractures typically have a history of trauma. They generally have a higher intensity of pain, can associate the onset with a traumatic event, and are seen early for medical treatment. In all three groups of patients, there is no obvious deformity on physical examination, but there is generally pain with internal rotation. A high index of suspicion must be maintained to avoid delay in diagnosis. Patients with displaced femoral neck fractures complain of pain in the entire hip region and lie with the affected limb shortened and externally rotated. Anteroposterior and high-quality cross-table lateral (obtained by flexing the uninjured, not the injured, hip) radiographs of the hip are necessary and sufficient to diagnose displaced, nondisplaced, and impacted fractures and for planning treatment. MRI (with Short TI Inversion Recovery STIR images) has been shown to be the quickest, most cost-effective way of correctly identifying radiographically occult fractures. Pending treatment, patients should be nonweight-bearing and allowed to rest with the limbs in the most comfortable position, which is generally in slight flexion on a pillow. Traction is not necessary and may increase pain.

D. Treatment

Stress fractures. These fractures commonly occur in young, vigorous individuals and require careful evaluation. A high index of suspicion for this injury should be kept for active patients presenting with groin pain.⁹ Patients with femoral neck stress fractures often have decreased bone density compared with age-matched controls.¹⁰ Femoral neck stress fractures may heal uneventfully but have the potential to displace, especially if on the superior/lateral side. Upon diagnosis, patients should be treated by restricted weight bearing. Use of crutches or a walker is mandatory, and patients should also be cautioned not to attempt straight-leg raising exercises and not to use the leg for leverage in rising or in changing positions, particularly getting up out of a chair. Partial weight bearing is safe within 6 weeks, with full weight bearing in 12 weeks, as long as the fracture shows roentgenographic evidence of healing, which is evidenced by sclerosis at the superior femoral neck. Because of the potentially severe complications of displacement (nonunion, osteonecrosis, need for surgery), in situ pinning should be considered in active or unreliable patients or any patient with a tension (superior-lateral) fracture. Compression types of fractures in elderly individuals generally do well with limiting activity as outlined above. Functional complaints may persist for years in patients with femoral neck stress fractures.¹¹
Impacted fractures

a. These can be treated either nonoperatively or operatively.^3,12 With the nonoperative method, the patient usually is kept in bed for a few days with the leg protected from rotational stresses until the muscle spasms subside. A program of protected ambulation, as outlined for stress fractures, is then initiated. In a series of over 300 patients with impacted femoral neck fractures treated nonoperatively, displacement only occurred in 5% of younger, healthy patients.¹² When displacement occurred in these patients, operative treatment led to a successful outcome in all cases.¹² Although the authors of this study suggest that surgery is only necessary in patients over age 70 with multiple medical problems, others would argue that even a 5% risk of late displacement is unacceptable.

b. Internal fixation of impacted fractures has many advantages over nonoperative methods, especially using percutaneous technique. Although the rate of avascular necrosis (AVN) may not be different, a union rate of 100% in operative cases has been reported, compared with 88% with closed management. A recent matched pair study compared internal fixation of nondisplaced fractures with hemiarthroplasty in displaced fractures, showing dramatic benefits in the internal fixation group and suggesting that hemiarthroplasty should not be done in nondisplaced fractures.¹³ The authors recommend multiple screw fixation in patients with nondisplaced fractures, either percutaneous or by open technique, because it allows immediate weight bearing and avoids the risk of late displacement (see I.F).

3. Displaced fractures. The management of displaced femoral neck fractures is surgical; the best surgical approach (internal fixation vs. arthroplasty) continues to be an area of controversy.^14,15 Within each method, there is also controversy about the best method of fixation (multiple screws or dynamic hip screw) or optimum type of arthroplasty (unipolar, bipolar, or total).¹⁶ The optimum treatment for a given patient is based on the activity level of the patient before the fracture; this is a direct measure of the functional demands of the patient and activity level correlates with bone density.³ Patients must be treated with an understanding of their physical and mental abilities. It is important to rapidly arrange family discussions and explain the risks and benefits of the various surgical interventions to the patient’s family.

The most difficult situation is the active patient with a displaced femoral neck fracture. Fractures in healthy patients younger than 60, with or without slight comminution, should be reduced, impacted, and internally fixed. Although the literature is not definitive, there is consensus that surgery should be undertaken as quickly as possible.^17–19 Intracapsular tamponade from fracture hematoma has an unfavorable effect on femoral head blood flow, as does nonanatomic position, so there is a rationale for proceeding with some urgency.^3,20,21 However, patients with dehydration or unstable cardiac conditions should be medically stabilized before surgery to minimize the risk of fatality.^18,19 There is consensus that accurate reduction and impaction at the fracture site are essential to a good end result. Anatomic reduction allows the maximum opportunity for reestablishment of the vascular supply. Any stretch or kinking of the vessels of the ligamentum teres or retinaculum is avoided while stability of the fracture is optimized.²⁰ Internal fixation is clearly associated with an increased risk of reoperation compared with arthroplasty.^14,15,22 There is also recent evidence that too much shortening of the femoral neck at the time of final healing leads to a poor outcome.²³ A reliable method to surgically repair femoral neck fractures without loss of fixation or some collapse of the femoral neck remains an elusive goal.

E. Reduction techniques

1. The authors favor a closed reduction on a fracture table that then allows for the insertion of internal fixation under biplanar image-intensifier control. Manipulative reduction should be gentle, and the authors have found the techniques of McElvenny and Deyerle to be the most satisfactory. Frequently, however, the fracture is reduced by the maneuver of applying traction on the limb with neutral adduction–abduction with internal rotation to bring the femoral neck parallel to the floor. Nonanatomic reduction should not be accepted; if acceptable reduction is not obtainable by closed means then open reduction should be considered.

a. In McElvenny’s technique, both extremities are placed in traction with the hips in extension. The affected leg is lined up with the long axis of the body and is then maximally internally rotated by rotating the knee rather than the foot to reduce stress on the knee ligaments. Traction is then released on the contralateral side. After viewing follow-up radiographs, if more valgus is required, the traction may be reapplied to the affected leg. Just before releasing the traction on the opposite leg, an abduction force at the knee is applied along with a simultaneous pushing inward over the trochanter.

b. The Deyerle technique achieves final alignment of the femoral neck and head in the lateral plane by a direct push posteriorly by two hands placed anteriorly over the greater trochanter while the pelvis on the contralateral side is supported to prevent ligament stress. This procedure is carried out after traction and internal rotation have reduced the fracture in the anteroposterior plane and before placement in slight valgus as described in a.

2. Open reduction. Open reduction is performed through either a Smith-Petersen anterior approach or a Watson–Jones anterolateral approach whenever a satisfactory closed reduction cannot be obtained in a patient in whom prosthetic replacement is contraindicated.³ Although fracture site visualization may be best with the anterior approach, the screws have to be inserted through a separate lateral incision. The Watson–Jones interval is a more familiar approach for many surgeons, but fracture visualization may be a little more difficult.

F. Operative techniques

Choice of operative technique depends on the assessment of fracture displacement, location within the femoral neck, amount of comminution, and the angle of the fracture line.

Multiple screws. Fixation of the femoral neck with multiple screws is the simplest method of obtaining internal fixation. This method is ideal for transcervical or subcapital fractures that are not too vertical or too comminuted, and can be a percutaneous procedure, thus reducing the risk of infection and the operative morbidity in elderly patients, extremely poor-risk patients, and bedridden patients. When an adequate (anatomic) closed reduction is obtained, the screws can be placed through a small lateral incision, but a capsulotomy is recommended by extending the deep dissection anteriorly. When the reduction is nonanatomic, open reduction is advised.^3,21

Internal fixation with three pins or screws secures fracture stability; there is no value in using more than three implants.²⁴ An exception to this generalization is the fracture comminuted with posterior comminution; in this instance the addition of a fourth screw²⁵ or use of a dynamic hip screw may confer more stability. Screws should be placed around the periphery of the femoral neck, immediately adjacent to the cortex.²⁶ Usually, one screw is placed along the medial neck in a central position, another posteriorly, and the third screw anteriorly.

2. Sliding hip screw fixation is an alternative to multiple screws. This method is usually chosen for fixation of basicervical fractures or the more vertical fracture patterns. With anatomic reduction, no mechanical advantage is obtained with the hip screw because fracture stability is most dependent on the quality of the reduction and the density of the bone in the femoral head. However, with a nonanatomic reduction, there is an advantage to the use of a hip screw because the fixation relies on the lateral cortex rather than opposition of the fracture surface.^20,24 A sliding screw plate appears to have the advantage of firm fixation of the head, as well as allowing for impaction through sliding in a fitted barrel. An additional threaded pin or cancellous screw should be placed superiorly in the neck and head for improved torsional control.²⁰ Regardless of the particular type of mechanism used, it is essential to obtain maximum holding capacity in the head, which necessitates the use of a 135° angle device in most individuals when anatomic reduction is obtained. When a valgus reduction is chosen, it is important to use a 150° nail plate device and to position the nail or screw in the deepest portion of the head.

3. Prosthetic replacement. Many studies have demonstrated improved functional outcomes, dramatically lower reoperation rates, and more cost-effectiveness with hemiarthroplasty and total hip replacement when compared with internal fixation of displaced femoral neck fractures.^14,22,27 However, arthroplasty procedures carry a higher risk of deep infection, dislocation, and potential need for revision.²⁸ Use of an anterior or lateral approach significantly decreases the risk of dislocation.²⁸ Hemiarthroplasty of the hip may be performed with unipolar or bipolar components. Traditionally, a unipolar prosthesis is used for patients with very low functional demand, whereas bipolar devices are used in patients with higher functional demands. However, recent studies have failed to demonstrate any significant difference in outcomes with either type of device,²⁹ while bipolar components may contribute polyethylene wear particles with time.³⁰ Many studies seem to indicate that total hip arthroplasty (THA) provides superior functional results in active patients compared with hemiarthroplasty,³¹ but a recent systematic review of the topic was unable to make a definitive statement.¹⁶ THA is considered to have a higher risk of dislocation,^16,32 but the magnitude of this risk is not clearly defined and seems to be decreasing with modern arthroplasty techniques.³¹ In the more typical older patient, there may be little advantage to THA over hemiarthroplasty.³² Fortunately, the risk of recurrent dislocation and reoperation are not different than those after primary THA.³³ The use of larger femoral heads with cross-linked polyethylene and avoidance of posterior approaches reduce the risk of dislocation.³¹ Total hip replacement is certainly an appropriate choice in active patients above age 65 with a displaced femoral neck fracture.³¹

4. The authors’ preference is multiple screw fixation or a sliding hip screw with an additional pin or screw appears to offer optimum fixation.^3,21 The techniques are not easily learned or applied and are only effective with anatomic reduction and maximum fracture impaction at the time of surgery. Given the difficulties inherent with either technique, the uncertain end-results if anatomic reduction is not obtained, and risk of AVN, the surgeon should consider total hip replacement as an alternative in the older patient with normal function, or hemiarthroplasty in the patient with low functional demands and poor bone quality.²⁸

G. Failed primary fixation. The most frequent complications following internal fixation of displaced femoral neck fracture are loss of reduction, protrusion of the screw or pins into the acetabulum, and collapse with symptomatic AVN. These complications are reliably salvaged by THA.

H. Postoperative care and rehabilitation. The aim of treatment is to return the patient to preoperative status by the quickest, safest method. Therefore, rehabilitation planning should begin at the time of admission because most patients are elderly and do not tolerate prolonged periods away from familiar environments. Surgery is carried out as soon as possible, and the procedure should be one that allows immediate weight bearing to tolerance, the first step in rehabilitation. As long as stable internal fixation is achieved, gains from early weight bearing far outweigh the risks. Patients are encouraged to ambulate and to apply as much weight as is comfortable. Initially, a walker is used, and then gradual progress is made to crutches, if practical, and eventually a cane. In the case of the patient with balance problems, the walker or cane may be used indefinitely to help prevent more falls.

I. Nonunion and avascular necrosis

In the past, nonunion has been an important complication of displaced femoral neck fractures, but with proper reduction, impaction, and internal fixation, its incidence should be reduced to less than 10%.^3,28 Most fractures heal promptly and the union is well established within 4 months. Occasionally, there is some resorption at the fracture site, probably a result of insufficient impaction at surgery and therefore some fracture instability. Further impaction and eventual healing usually occur, but the incidence of AVN is significantly higher than in patients who obtain primary union.
Avascular necrosis

a. The roentgenographic signs of AVN, with associated collapse, can occur at any time postoperatively. For practical purposes, however, changes with collapse are usually seen within 3 years. The incidence of AVN is variously reported to be between 7% and 35%, and it must be appreciated that for displaced femoral neck fractures, the head, or at least a major portion of it, is rendered avascular at the time of injury.^3,28 The most recent data regarding the risk of AVN were presented by Loizou and Parker.³⁴ In their study of 1,023 patients with femoral neck fractures, the overall rate of AVN was 6.6%. AVN was less common for undisplaced (4.0%) than displaced fractures (9.5%) and was less common in men (4.9%) than women (11.4%) who had a displaced fracture. The incidence of AVN in patients younger than 60 years with a displaced fracture was 20.6%, compared with 12.5% for those aged 60 to 80 years and 2.5% among those elder than 80 years.³⁴ When avascular changes are identified, the patient should be managed according to symptoms. In many older patients, the condition may not be severe enough to warrant any further surgery, but in patients with complete collapse of the femoral head and increasing pain, early total hip replacement is the treatment of choice.

b. The role of bone grafting for either prevention or treatment of AVN remains uncertain. Currently, evidence for use of bone grafting for either of these conditions on a routine basis is lacking.

J. Prognosis. Anticipated complications and end results have been discussed for each fracture. Because of the advanced age of the typical patient, development of degenerative articular changes over a long period is difficult to assess, but it does not appear to be a frequent complication. The morbidity and mortality rates (12% for the 12 months following fracture) are high, but they can be notably decreased by treating this fracture with early reduction and early ambulation. The mortality rates return to those of age-matched control subjects after 1 year.

K. Fractures of the neck of the femur in children^35,36

Treatment

a. Transepiphyseal fractures are uncommon, and there is no series of sufficient size to make any conclusions about the treatment of choice. The authors recommend reduction with capsulotomy and fixation with smooth pins.³⁶

b. Undisplaced and minimally displaced cervicotrochanteric fractures carry a risk of AVN. The pathophysiology may involve intracapsular tamponade of the vessels supplying the femoral head.³⁶ The authors recommend capsulotomy, reduction if necessary, and fixation with lag screws short of the femoral head epiphysis. The screws are generally sufficient because of the density of the bone. In children 8 years old and younger, postoperative spica cast immobilization is also used for 6 to 12 weeks. Displaced fractures are treated in the same way. These fractures must be treated emergently to minimize the complication of AVN.

2. Prognosis. These fractures have nearly a 100% rate of union with optimum management.

3. Complications

a. Coxa vara. Although this complication is commonly reported, it is generally associated with nonoperative management.

b. Avascular necrosis. This complication affects 0% to 17% of patients who undergo emergent treatment. The long-term consequence is generally degenerative arthritis, which requires THA in patients in their 40s to 60s.

c. Premature closure of the epiphysis occurs in less than 10% of cases and is not a significant long-term problem except when it occurs in children younger than 8 years.

II. INTERTROCHANTERIC FRACTURES

A. Surgical anatomy

The classic intertrochanteric fracture occurs in a line between the greater and lesser trochanters. Although in theory such a fracture is totally extracapsular, the distinction between an intertrochanteric fracture and a basilar femoral neck fracture is not always clear. In peritrochanteric fractures, the internal rotators of the hip remain with the distal fragment, whereas usually at least some of the short, external rotators are still attached to the proximal head and neck fragment. This factor becomes important in reducing the fracture because, in order to align the distal fragment to the proximal one, the leg must be in some degree of external rotation. This is in contrast to the internal rotation often needed to reduce transcervical femoral neck fractures and requires a distinctly different maneuver in the operating room with the patient on the fracture table to reduce the fracture.
When the forces producing the fracture are increased, the greater trochanter and lesser trochanter can be separately fractured and appear as separated fragments (three- and four-part fractures). Secondary comminution is not infrequent and usually involves one of the four major fragments. Anatomic restoration becomes a major undertaking but is not necessary to obtain a satisfactory result from a functional point of view. Occasionally, a subtrochanteric extension of the fracture is encountered.

B. Mechanism of injury. The intertrochanteric fracture almost invariably occurs as a result of a fall in which both direct and indirect forces are acting. Direct forces act along the long axis of the femur or directly over the trochanter. Indirect forces include the pull of the iliopsoas muscle on the lesser trochanter and that of the abductors on the greater trochanter.

C. Classification. Several classifications and subclassifications have been proposed.^37–39 From the standpoint of treatment and prognosis, a simple classification into stable or unstable fractures is most satisfactory.

A stable intertrochanteric fracture is one in which it is possible for the medial cortex of the femur to butt against the medial cortex of the calcar of the femoral neck fragment. Not uncommonly, the lesser trochanter is fractured off as a small secondary fragment, but this does not interfere with the basic stability of the fracture.
The unstable intertrochanteric fracture is one in which there is comminution of the posteromedial-medial cortex (along the calcar femorale), involvement of the lateral wall,^40,41 or an associated fracture of the femoral neck.³⁹ In the most common unstable pattern, a large posteromedial fragment encompasses the lesser trochanter, with or without a fracture through the greater trochanter (four-part fracture). A fracture with high obliquity may be considered unstable because of the high shearing force at the fracture site despite anatomic reduction and internal fixation. Within the last few years, the importance of the integrity of the lateral wall of the greater trochanter has been highlighted.^40,41 In fractures where a fracture line exits lateral to the tip of the greater trochanter, intraoperative fracture of the lateral wall can be expected to occur when using a sliding hip screw, which in turn predictably leads to maximal collapse, shortening, and a poor outcome.⁴¹