INTERTROCHANTERIC

FRACTURES

EPIDEMIOLOGY

Intertrochanteric fractures account for nearly 50% of all fractures of the proximal femur.

There are approximately 150,000 intertrochanteric fractures annually in the United States with an annual incidence of 63 and 34 per 100,000 population per year for elderly females and males, respectively.

The ratio of women to men ranges from 2:1 to 8:1, likely because of postmenopausal metabolic changes in bone.

Some of the factors associated with intertrochanteric rather than femoral neck fractures include advancing age, increased number of comorbidities, increased dependency in activities of daily living, and a history of other osteoporosis-related (fragility) fractures.

ANATOMY

Intertrochanteric fractures occur in the region between the greater and lesser trochanters of the proximal femur, occasionally extending into the subtrochanteric region.

These extracapsular fractures occur in cancellous bone with an abundant blood supply. As a result, nonunion and osteonecrosis are less problematic than in femoral neck fractures.

Deforming muscle forces will usually produce shortening, external rotation, and varus position at the fracture.

• Abductors tend to displace the greater trochanter laterally and proximally.

• The iliopsoas displaces the lesser trochanter medially and proximally.

• The hip flexors, extensors, and adductors pull the distal fragment proximally.

Fracture stability is determined by the presence of posteromedial bony contact, which acts as a buttress against fracture collapse.

MECHANISM OF INJURY

Intertrochanteric fractures in younger individuals are usually the result of a high-energy injury such as a motor vehicle accident or fall from a height.

Ninety percent of intertrochanteric fractures in the elderly result from a simple fall.

Most fractures result from a direct impact to the greater trochanteric area.

CLINICAL EVALUATION

It is the same as for femoral neck fractures (see Chapter 29).

Patients may have experienced a delay before hospital presentation. This time is usually spent on the floor and without oral intake. The examiner must therefore be cognizant of potential dehydration, nutritional depletion, venous thromboembolic disease (VTE), and pressure ulceration issues as well as hemodynamic instability because intertrochanteric fractures may be associated with as much as a full unit of hemorrhage into the thigh.

RADIOGRAPHIC EVALUATION

An anteroposterior (AP) view of the pelvis and an AP and a cross-table lateral view of the involved proximal femur are obtained.

A physician-assisted internal rotation view of the injured hip may be helpful to clarify the fracture pattern further.

Magnetic resonance imaging (MRI) is currently the imaging study of choice in delineating nondisplaced or occult fractures that are not apparent on plain radiographs. Bone scans or computed tomography (CT) scanning is reserved for those who have contraindications to MRI.

CLASSIFICATION

Evans (Fig. 30.1)

This is based on prereduction and postreduction stability, that is, the convertibility of an unstable fracture configuration to a stable reduction.

In stable fracture patterns, the posteromedial cortex remains intact or has minimal comminution, making it possible to obtain and maintain a stable reduction.

Unstable fracture patterns are characterized by greater comminution of the posteromedial cortex. Although they are inherently unstable, these fractures can be converted to a stable reduction if medial cortical opposition is obtained.

The reverse obliquity pattern is inherently unstable because of the tendency for medial displacement of the femoral shaft.

The adoption of this system was important not only because it emphasized the important distinction between stable and unstable fracture patterns but also because it helped define the characteristics of a stable reduction.

Orthopaedic Trauma Association Classification of Intertrochanteric Fractures See Fracture and Dislocation Classification Compendium at http://www.ota.org/compendium/compendium.html.

Several studies have documented poor reproducibility of results based on the various

intertrochanteric fracture classification systems.

Many investigators simply classify intertrochanteric fractures as either stable or unstable, depending on the status of the posteromedial cortex. Unstable fracture patterns comprise those with comminution of the posteromedial cortex, subtrochanteric extension, or a reverse obliquity pattern.

UNUSUAL FRACTURE PATTERNS

Basicervical Fractures

Basicervical neck fractures are located just proximal to or along the intertrochanteric line (Fig. 30.2).

Although anatomically femoral neck fractures, basicervical fractures are usually extracapsular and thus behave and are treated as intertrochanteric fractures.

They are at greater risk for osteonecrosis than the more distal intertrochanteric fractures.

They lack the cancellous interdigitation seen with fractures through the intertrochanteric region and are more likely to sustain rotation of the femoral head during implant insertion.

Reverse Obliquity Fractures

Reverse obliquity intertrochanteric fractures are unstable fractures characterized by an oblique fracture line extending from the medial cortex proximally to the lateral cortex distally (Fig. 30.3).

The location and direction of the fracture line result in a tendency to medial displacement from the pull of the adductor muscles.

These fractures should be treated as subtrochanteric hip fractures.

TREATMENT

Nonoperative

This is indicated only for patients who are at extreme medical risk for surgery; it may also be considered for demented nonambulatory patients with mild hip pain.

Nondisplaced fractures can be considered for nonoperative treatment because, unlike with femoral neck fractures, displacement changes neither the operation type nor outcome.

Early bed to chair mobilization is important to avoid increased risks and complications of prolonged recumbency, including poor pulmonary toilet, atelectasis, venous stasis, and pressure ulceration.

Resultant hip deformity is both expected and accepted in cases of displacement.

Operative

The goal is stable internal fixation to allow early mobilization and full weight-bearing ambulation. Stability of fracture fixation depends on:

• Bone quality

• Fracture pattern

• Fracture reduction

• Implant design

• Implant placement

  Timing of Surgery

Abundant evidence exists that surgery should be performed in a timely fashion, once the patient has been medically stabilized.

Fixation Implants

Sling Hip Screw

This has historically been the most commonly used device for both stable and unstable fracture patterns. It is available in plate angles from 130 to 150 degrees (Fig. 30.4).

The most important technical aspects of screw insertion are (1) placement within 1 cm of subchondral bone to provide secure fixation and (2) central position in the femoral head (tip–apex distance).

The tip–apex distance can be used to determine lag screw position within the femoral head. This measurement, expressed in millimeters, is the sum of the distances from the tip of the lag screw to the apex of the femoral head on both the AP and lateral radiographic views (after controlling for radiographic magnification) (Fig. 30.5). The sum should be <25 mm to minimize the risk of lag screw cutout.

Biomechanical and clinical studies have shown no advantage of four screws over two to stabilize the side plate.

At surgery, the surgeon must be prepared to address any residual varus angulation, posterior sag, or malrotation.

A 4% to 12% incidence of loss of fixation is reported, most commonly with unstable fracture patterns.

Most failures of fixation are attributable to technical problems of screw placement and/or inadequate impaction of the fracture fragments at the time of screw insertion.

Clinically, more shortening and deformity is seen with the use of sliding hip screw (SHS) in unstable patterns.

The SHS is the lowest cost implant available for these fractures.

Intramedullary Hip Screw Nail

This implant combines the features of an SHS and an intramedullary nail (IMN) (Fig. 30.6).

Advantages are both technical and mechanical: Theoretically, these implants can be inserted in a closed manner with limited fracture exposure, decreased blood loss, and less tissue damage than an SHS. In addition, due to their intramedullary location, these devices are subjected to a lower bending moment than the SHS. Use of the intramedullary hip screw limits the amount of fracture collapse, compared with an SHS.

Most studies have demonstrated no clinical advantage of the intramedullary hip screw compared

with the SHS in stable fracture patterns.

Use of intramedullary hip screws has been most effective in intertrochanteric fractures with subtrochanteric extension and in reverse obliquity fractures.

Use of older design intramedullary hip screws has been associated with an increased risk of femur fracture at the nail tip or distal locking screw insertion point.

Prosthetic Replacement

This has been used successfully for patients in whom open reduction and internal fixation (ORIF) have failed and who are unsuitable candidates for repeat internal fixation.

A calcar replacement hemiarthroplasty may be needed because of the level of the fracture.

Primary prosthetic replacement for comminuted, unstable intertrochanteric fractures has yielded up to 94% good functional results in limited series.

Disadvantages include morbidity associated with a more extensive operative procedure, the internal fixation problems with greater trochanteric reattachment, and the risk of postoperative prosthetic dislocation.

External Fixation

This is not commonly considered for the treatment of intertrochanteric femur fractures.

Early experiences with external fixation for intertrochanteric fractures were associated with postoperative complications such as pin loosening, infection, and varus collapse.

Recent studies have reported good results using hydroxyapatite coated pins.

Special Considerations

When using an SHS, greater trochanteric displacement should be fixed via tension band techniques or a trochanteric stabilizing plate and screw construct.

Basicervical fractures treated with an SHS or IMN may require a supplemental antirotation screw or pin during implant insertion.

Reverse obliquity fractures are best treated as subtrochanteric fractures with either a 95-degree fixed angle implant or an intramedullary device.

Ipsilateral fractures of the femoral shaft, although more common in association with femoral neck fractures, should be ruled out when the injury is caused by high-energy trauma.

Rehabilitation

Early patient mobilization with weight bearing as tolerated ambulation is indicated.

COMPLICATIONS

Loss of fixation: This most commonly results from varus collapse of the proximal fragment with cutout of the lag screw from the femoral head; the incidence of fixation failure is reported to be as high as 20% in unstable fracture patterns. Lag screw cutout from the femoral head generally occurs within 3 months of surgery and is usually caused by one of the following:

• Eccentric placement of the lag screw within the femoral head (most common)

• Improper reaming that creates a second channel

• Inability to obtain a stable reduction

• Excessive fracture collapse such that the sliding capacity of the device is exceeded

• Inadequate screw-barrel engagement, which prevents sliding

• Severe osteopenia, which precludes secure fixation

  • Management choices include (1) acceptance of the deformity, (2) revision ORIF, which may require methylmethacrylate, and (3) conversion to prosthetic replacement.

Nonunion: Rare, occurring in <2% of patients, especially in patients with unstable fracture

patterns. The diagnosis should be suspected in a patient with persistent hip pain and radiographs revealing a persistent radiolucency at the fracture site 4 to 7 months after fracture fixation. With adequate bone stock, repeat internal fixation combined with a valgus osteotomy and bone grafting may be considered. In most elderly individuals, conversion to a calcar replacement prosthesis is preferred.

Malrotation deformity: This results from internal rotation of the distal fragment at the time of internal fixation. When it is severe and interferes with ambulation, revision surgery with plate removal and rotational osteotomy of the femoral shaft should be considered.

With full-length IMNs, impingement or perforation of the distal aspect of the nail on the anterior femoral cortex can occur, secondary to a mismatch of the nail curvature and femoral bow.

Z-Effect: Seen most commonly with dual screw cephalomedullary trochanteric nails. Failure can result with the most proximal screw penetrating the hip joint and the distal screw backing out of the femoral head.

Osteonecrosis of the femoral head: This is rare following intertrochanteric fracture.

Lag screw-side plate dissociation

Traumatic laceration of the superficial femoral artery by a displaced lesser trochanter fragment

Iatrogenic injury to the superior gluteal artery during approach

Greater Trochanteric Fractures

Isolated greater trochanteric fractures, although rare, typically occur in older patients as a result of an eccentric muscle contraction or, less commonly, from a direct blow.

Treatment of greater trochanteric fractures is usually nonoperative.

Operative management can be considered in younger, active patients who have a widely displaced greater trochanter.

The preferred operative techniques are:

• ORIF with a tension band wiring of the displaced fragment and the attached abductor muscles (Fig. 30.7A)

• Plate and screw fixation with a “hook plate” (Fig. 30.7B)

   

   

   

  Lesser Trochanteric Fractures

These are most common in adolescence, typically secondary to forceful iliopsoas contracture.

In the elderly, isolated lesser trochanter fractures have been recognized as pathognomonic for pathologic lesions of the proximal femur.