Subtrochanteric Hip Fractures


Background

During the past 50 years, the treatment of subtrochanteric fractures has evolved in conjunction with improved understanding of both fracture biology and biomechanics. Previously, nonsurgical treatment of these fractures was associated not only with significant shortening and malrotation but also with the morbidity and mortality of prolonged immobilization. Early surgical repair techniques had unacceptably high complication rates; however, the benefits of restoring the anatomy and encouraging early mobilization are recognized and have led to significant research and improvement in implants. Currently, subtrochanteric fractures remain technically challenging, even to experienced fracture surgeons. [123]

The difficulty of treating these fractures stems in part from the fact that this injury pattern is anatomically distinct from other proximal femoral peritrochanteric fractures and in part from the difficult features of femoral shaft fractures. As a result, they must be treated with specially designed implants that can withstand significant muscular forces for prolonged periods of healing. These strong muscle forces deform the fracture fragments and make reduction difficult. In addition, comminution is common in this region, and implants must withstand significant early loading.

Not surprisingly, subtrochanteric fracture has significantly higher rates of malunion and nonunion than other femoral fractures do. Still, with an improved understanding of this fracture and the specific treatment options, successful results can be obtained. [12]

Anatomy

The subtrochanteric region of the femur, arbitrarily designated as the region between the lesser trochanter and a point 5 cm distal, consists primarily of cortical bone. The femoral head and neck are anteverted approximately 13º with respect to the plane of the femoral shaft. The piriformis fossa lies at the base of the neck and is oriented in line with the femoral shaft. The lesser trochanter is posteromedial, and it is the point of insertion for the psoas and iliacus tendons. The femoral shaft has both an anterior and a lateral bow.

The major muscles that surround the hip create significant forces that contribute to fracture deformity. The gluteus medius and minimus tendons attach to the greater trochanter and abduct the proximal fragment. The psoas and iliacus attach to the lesser trochanter and flex the proximal fragment. The adductors pull the distal fragment medially.

All of these muscles are well vascularized, and this can lead to significant hemorrhage at the time of injury or during surgical approaches. To approach the proximal lateral femur, the vastus lateralis must be split or elevated off the intermuscular septum close to the large perforating branches of the profunda femoris. Division of these vessels can lead to copious bleeding, making surgical exposure difficult. With open surgical procedures, meticulous handling of these vessels and soft tissue is of paramount importance because the blood supply is critical to fracture healing.

Pathophysiology

The subtrochanteric region of the femur heals predominantly through a primary cortical healing; consequently, a subtrochanteric fracture is quite slow to consolidate. [4In addition, this region is exposed to high stresses during activities of daily living. Axial loading forces through the hip joint create a large moment arm, with significant lateral tensile stresses and medial compressive loads.

The calcar is a portion of bone along the posteromedial femur, just below the lesser trochanter, that extends proximally into the posteroinferior femur. Significant compressive forces have been described in this region, which contribute to the dense cortical bone of the subtrochanteric femur. A man who weighs 200 lb can generate forces in excess of 1200 lb per square inch (psi). [5]

In addition to the bending forces, muscle forces at the hip also create torsional effects that lead to significant rotational shear forces. During normal activities of daily living, up to six times the body weight is transmitted across the subtrochanteric region of the femur. [6]

Etiology

In elderly patients, minor slips or falls that lead to direct lateral hip trauma are the most frequent mechanism of injury. [78This age group is also susceptible to metastatic disease that can lead to pathologic fractures. In younger patients, the mechanism of injury is almost always high-energy trauma, either from direct lateral trauma (eg, motor vehicle accident [MVA]) or from axial loading (eg, a fall from height).

Gunshot wounds cause approximately 10% of high-energy subtrochanteric femur fractures. Iatrogenic fractures may also occur secondary to stress risers following previous surgery on the proximal femur. [9]

Epidemiology

Subtrochanteric fractures account for approximately 10-30% of all hip fractures, and they affect persons of all ages. Most frequently, these fractures are seen in two patient populations—namely, older osteopenic patients who have sustained a low-energy fall [810and younger patients who have been involved in high-energy trauma. A more recently identified patient population consists of individuals who experience subtrochanteric fractures after bisphosphonate use. These so-called atypical fractures have a transverse or short oblique pattern with cortical thickening and a medial cortical "beak."

Prognosis

Relatively few data exist regarding the outcome of patients with subtrochanteric femur fractures. [11In young patients, these injuries are common among those with multiple traumatic injuries; thus, outcomes are likely to be poorer than those in patients with isolated femur fractures. Associated fractures and soft-tissue injuries to the knee can complicate rehabilitation efforts. In older patients, subtrochanteric fractures can be grouped with other proximal femur fractures with relatively high morbidity and mortality.


History and Physical Examination

Physical findings at the time of injury often include a shortened extremity on the fractured side. Significant swelling is frequently present, with tenderness to palpation in the proximal thigh region. The leg may lie in internal or external rotation. The patient cannot flex the hip or abduct the leg. Hemorrhage into the injured thigh may be substantial, and the patient should be monitored for systemic shock and compartment syndrome.

In high-energy fractures, a complete system examination must be performed. Associated injuries to the cranium, thorax, and abdomen (Waddell triad) must be recognized. [12Pelvic, spine, and long bone injuries are also common, especially on the ipsilateral side, and these should be identified early to optimize treatment and outcomes.

Classification

A universally accepted fracture classification does not exist for subtrochanteric femur fractures. The Arbeitsgemeinschaft für Osteosynthesefragen–Association for the Study of Internal Fixation (AO-ASIF), along with the Orthopaedic Trauma Association, developed a complicated three-part classification system with 10 subtypes (see the image below); this system has been most useful in research settings.

The Arbeitsgemeinschaft für osteosynthesefragen–AsThe Arbeitsgemeinschaft für osteosynthesefragen–Association for the Study of Internal Fixation (AO-ASIF) classification of subtrochanteric femur fractures.

In 2018, the OTA/AO fracture and dislocation compendium was revised and streamlined. [13 Further information is available on the AO Foundation Web site

In 1978, Seinsheimer presented an important classification with eight subgroups that identified fractures with loss of medial cortical stability (see the image below). [14]

The Seinsheimer classification of subtrochanteric The Seinsheimer classification of subtrochanteric femur fractures.

The Russell-Taylor classification system (see the image below) is helpful because it assists in determining the proper mode of treatment.

The Russell-Taylor classification of subtrochanterThe Russell-Taylor classification of subtrochanteric femur fractures.

Russell-Taylor type 1 fractures do not involve the piriformis fossa. They are subdivided into subtypes A (for fractures below the lesser trochanter) and B (for fractures involving the lesser trochanter). Type 2 fractures involve the piriformis fossa. Type 2A fractures have a stable medial buttress. Type 2B has no stability of the medial femoral cortex. These fractures may have varying degrees of proximal comminution, sometimes with extension into the femoral neck, and may present difficulty with implant choice.

Type 1 fractures can be treated with first-generation or second-generation intramedullary devices. Historically, type 2 fractures were treated by means of open reduction and internal fixation (ORIF) with plate and screw devices or fixed-angle implants. With advanced techniques and implant design, intramedullary fixation has been a successful tool with reliable rates of healing.

A study that evaluated inter- and intra-observer reliability of current classification systems for subtrochanteric femoral fracture found both the Russell-Taylor and the Seinsheimer classification found to be more reliable and reproducible than the AO classification in this setting.


Imaging Studies

Biplanar plain radiography is the basic and essential imaging study for the diagnosis of subtrochanteric femur fractures. Full-length anteroposterior (AP) views of the femur from the hip to the knee should be obtained. A cross-table lateral view of the hip allows evaluation of the femoral neck and assessment of the extent of the fracture. An AP view of the pelvis is also required, as well as views of the ipsilateral knee, because of the frequency of associated injuries.

Computed tomography (CT) is not usually useful or necessary for surgical planning in these injuries.

When a pathologic fracture is suspected, screening studies such as technetium bone scanning or magnetic resonance imaging (MRI) may be indicated to rule out other sites of skeletal involvement. Screening chest radiography is also necessary to screen for possible pulmonary metastases.



Approach Considerations

The goals of therapy for subtrochanteric fractures include the following:

  • Anatomic alignment
  • Early mobilization
  • Effective rehabilitation

Today, treatment of these fractures in adults is almost exclusively surgical. With the improvements in surgical techniques and implants, most of the treatment goals can typically be achieved by surgical means. Current indications for surgical treatment include the following:

  • Displaced and nondisplaced fractures in adults
  • Fractures in patients with multiple traumatic injuries
  • Open fractures
  • Severe ipsilateral extremity injuries
  • Pathologic fractures

In selected patients with grossly contaminated fractures and in patients who are medically unstable for surgical intervention, treatment with skeletal traction can be considered. In skeletally immature patients, traction followed by cast bracing is an accepted treatment option.

The use of indirect reduction techniques may prove beneficial in those fractures stabilized with plate fixation techniques. In 1989, Kinast et al demonstrated a lower delayed union/nonunion rate and more rapid consolidation with blade-plate fixation and indirect reduction than with blade-plate fixation via direct visualization. [16As minimally invasive plating techniques evolve and improve, applications in high-energy proximal femoral fractures may become feasible and allow for a more biologically favorable approach with less soft-tissue dissection and disruption of native blood supply.

There is no literature regarding total hip arthroplasty (THA) for subtrochanteric fractures in elderly patients, and any conclusions must be extrapolated from data regarding THA for femoral neck fractures or intertrochanteric fractures. This body of literature suggests possible functional advantages, such as more rapid mobilization and shorter lengths of stay in select groups (eg, pathologic fractures, fractures in patients with renal disease, patients with pre-existing arthritis). Thus, the authors consider THA in this fracture type quite controversial. [17]

In September 2014, the American Academy of Orthopaedic Surgeons (AAOS) released a clinical practice guideline for the management of hip fractures in elderly patients (see Guidelines). [18]

Nonoperative Therapy

Even though current treatment of subtrochanteric fractures in adults is almost entirely surgical, a number of nonsurgical treatment protocols are of historic interest. In the late 1960s, cast bracing was used, but it was soon abandoned because of poor results with fractures in the subtrochanteric region. Treatment with traction was also advocated, followed by fracture bracing with a hip spica cast. At present, however, with increasing evidence of the morbidity of prolonged bed rest in elderly people or in patients with multiple traumatic injuries, nonoperative treatment methods are seldom used.

In selected patients with grossly contaminated fractures and in patients who are medically unstable for any surgical intervention, treatment with traction remains an option. It is important to realize that traction is associated with fracture malalignment problems and joint stiffness in the adult patient. However, in skeletally immature patients, traction followed by cast bracing is still a viable treatment option. [1920]

Surgical Therapy

Surgical treatment can be divided into the following three main techniques:

  • External fixation
  • Open reduction with plates and screws
  • Intramedullary fixation

External fixation is rarely used but is indicated in severe open fractures. For most patients, external fixation is temporary, and conversion to internal fixation can be made if and when the soft tissues have healed sufficiently. External fixation becomes complicated when significant fracture comminution extends proximally, which may necessitate more proximal stabilization to the iliac crest. [1921222324]

In 1984, Tencer compared the biomechanical attributes of seven different plate and intramedullary fixation devices for subtrochanteric femur fractures. [25Femur-implant constructs using intramedullary devices had up to 5% torsional stiffness as compared with intact cadaveric femora tested identically, whereas plate-fixed fractures were nearly 50% as stiff. In combined bending and compression to failure, a test to simulate forces due to body weight, the intramedullary locked rods were found to support 300-400% of body weight, whereas the plate systems failed at loads of 100-200% of body weight. [26]

When plate fixation is chosen for fixation of subtrochanteric fractures, the traditional option is the Arbeitsgemeinschaft für Osteosynthesefragen–Association for the Study of Internal Fixation (AO-ASIF) blade plate. This implant was first used several decades ago, with variable success rates. High union rates were reported when the procedure was appropriately planned, and medial dissection was avoided. However, high rates of complications were also reported with this technique.

As a result of the complications and the technical difficulties inherent in the blade-plate technique, [2728the sliding hip screw (dynamic hip screw [DHS]) and the dynamic condylar screw (DCS) evolved as treatment options. [29303132These devices were believed to allow fracture impaction, and they had the biomechanical advantages of the blade plate but with a less complicated insertion technique. Several early reports suggested good rates of fracture union and low complication rates with both devices.

Subsequently, anatomically contoured locking plates emerged as a treatment option for subtrochanteric fractures. These also feature a simplified insertional technique and can be placed via smaller incisional portals. Long-term and high-quality comparative studies of these devices versus the angled blade plate are lacking, but success rates with their use are probably similar to those with angled blade plates and are reliant on biologically favorable, indirect reduction techniques.

Intramedullary nails are emerging as the treatment of choice for subtrochanteric femur fractures. [333435The most widely used nails are either centromedullary (contained within the medullary canal) or cephalomedullary (including those that affix to the femoral neck and head; see the image below).

Subtrochanteric femur fracture repaired with cephaSubtrochanteric femur fracture repaired with cephalomedullary device

Essentially all subtrochanteric fractures below the level of the lesser trochanter can be nailed with a centromedullary locking nail. For fractures with extension above the lesser trochanter (Russell-Taylor type 2), a fixed-angle device such as a blade-plate or DCS can be used, but these seem to provide less predictable results. Most type 2A and 2B fractures can be successfully treated with cephalomedullary nails, such as the Richards reconstruction nail. [36 (See the images below.)

Reverse obliquity subtrochanteric femur fracture mReverse obliquity subtrochanteric femur fracture malreduced with a short cephalomedullary nail
Subtrochanteric femur fracture reduction revised aSubtrochanteric femur fracture reduction revised and stabilized with a blade plate. Patient went on to heal and return to full function without pain.

It is important to beware of the use of hip fracture implants (compression-screw cephalomedullary nails); these are not the ideal implants for most subtrochanteric fractures, because of the large amount of bone that must be removed in the trochanteric and head areas and because of the limited canal-diameter options that do not allow the use of a canal fitting nail.

Xu et al compared outcomes and complications of titanium elastic nail and open reduction with plate fixation in 67 shool-aged children (age range, 5-12 years) with subtrochanteric femur fractures. [37 All 67 fractures united properly, with no major postoperative complications. In the titanium nail group, 24 excellent and 15 satisfactory results were reported, compared with 19 excellent and nine satisfactory results in the open plating group. Both techniques were considered  to be safe and effective  for treating subtrochanteric fractures in this population.

Operative details

Preoperative templating is advisable. Treatment of subtrochanteric fractures is technically demanding, and the surgeon needs flexibility in the choice of implant and approach.

When proximal comminution requires the use of a fixed-angle device, detailed templating is required to ensure that an implant with the proper blade or compression screw length, as well as plate length, is chosen. When an intramedullary device is chosen, templating for length, as well as canal diameter, is necessary for proper planning. In addition, because significant comminution could make limb length determination difficult, it can be helpful to obtain radiographs of the unaffected femur with a ruler to ascertain the normal femur length.

The proximal fracture fragment is invariably flexed and externally rotated. If a reconstruction-type nail is chosen, it is particularly difficult to locate the piriformis fossa in the proximal fragment. Occasionally, a small incision with insertion of a bone hook, fracture clamp, or Schanz pin can be helpful to orient the proximal fragment.

During intramedullary nailing, the intramedullary fracture reduction tool is frequently helpful to reduce the proximal fragment for guide-wire passage. Small incisions and use of percutaneous instruments to manipulate fragment position are helpful and do not have frequently described complications. Care must be taken to maintain the reduction during reaming to avoid eccentric reaming and fracture malposition after nail insertion.

Many techniques, both percutaneous and open, have been described to aid in reduction of these difficult fractures. [38Accuracy of reduction is the most important factor to offload the high stresses seen by these load-sharing implants and prevent hardware failure and subsequent nonunion. [39 Open reduction, if indicated, may be facilitated by the use of cerclage wiring. [4041]

If a trochanteric nail or off-axis nail is chosen, the entry point for the device may be easier to localize, even with small incisions. Still, malrotation of the fracture fragments can make this task difficult. However, the insertion angle must match the valgus of the nail design to avoid frontal plane deformity, and poor insertional vectors are common with this fracture.

In addition, proximal fragment comminution makes reduction and positioning of the head and neck fragment challenging. During plating, comminution at the proximal lateral femur can make lateral start-site localization very difficult. It is frequently helpful to position a guide wire anteriorly on the femoral neck, approximating the axis of the femoral neck, to assist in proper orientation of the starting chisel in the proximal femoral fragment.

Fractures with large fragments and limited comminution can typically be reduced with traditional techniques, including lag screw fixation of fragments followed by plate neutralization. However, in the presence of severe comminution, indirect reduction and minimally invasive bridge plating techniques may preserve the soft tissues and contribute to successful union. Acute bone grafting is occasionally suggested but is most likely to be appropriate in the setting of comminution, including the medial cortical buttress along the proximal calcar region of the proximal femur in closed fractures.

In the setting of pathologic fractures, prophylactic stabilization of the entire femur may be indicated to prevent problems with multiple metastases in the same bone and facilitate possible treatment with radiotherapy. If an intramedullary device is chosen, care must be taken to ensure that adequate material for biopsy is obtained, usually with the intramedullary reamings. If necessary, open fracture reduction may be facilitated to obtain adequate material for pathologic analysis.

Postoperative Care

After intramedullary nailing, if bone quality and cortical contact are adequate, 50% partial weightbearing can be allowed immediately. With less stability, patients can perform touchdown weightbearing. After open reduction and internal fixation (ORIF) and plate fixation, minimal protected weightbearing can begin immediately but is advanced slowly, beginning approximately 4 weeks after surgery, with full weightbearing anticipated at 8-12 weeks.

Elderly patients may have difficulty with compliance with weightbearing restrictions. Such patients are slow to progress and generally avoid aggressive weightbearing on the injured extremity. As a result, most elderly patients can be safely permitted to progress to full postoperative weightbearing status. [10]

Complications

Common complications include the following [4243:

  • Nonunion
  • Malunion
  • Failure of fixation
  • Deep vein thrombosis (DVT)
  • Wound infection

Nonunion is usually accompanied by significant pain after 4-6 months with the inability to bear full weight. If nonunion is not obvious on plain radiography, tomography may help delineate it; occasionally, bone scanning can be helpful. In the presence of stable fixation, autogenous bone grafting can lead to successful fracture unions. In patients treated with intramedullary nails, exchange nailing with overreaming is also appropriate, with or without static locking of the new nail device.

Malunion is usually evident as a limp from shortening or rotational deformity with limitation of hip rotation. Frequently, gross rotational deformity can be detected before a patient is awakened from an intramedullary nailing procedure and can be corrected at that time. Late detection of malrotation may necessitate a derotational osteotomy of the affected bone. Shortening is often secondary to varus at the neck shaft junction and can be addressed with a valgus osteotomy.

Failure of a screw-plate device can be salvaged with a repeat plating and bone graft procedure or with second-generation nailing.

Mechanical and chemical prophylaxis for DVT should be employed appropriately after fractures of the proximal femur. Diagnostic modalities, including Doppler ultrasonography (US) and computed tomography (CT) of the chest, should be used accordingly when DVT or pulmonary embolism (PE) is suspected.

Deep sepsis may be manifested by fracture nonunion. Workup for infection involves a standard hematologic analysis, including white blood cell (WBC), erythrocyte sedimentation rate (ESR), and C-reactive protein (CRP) level. In addition, aspiration can occasionally be diagnostic. Finally, WBC scanning can also provide information about deep infection.

Long-Term Monitoring

Close follow-up is required after fixation of subtrochanteric fractures. The wound is checked for proper healing 7-14 days postoperatively. The patient should have monthly clinical evaluations and radiographs to monitor healing. Quadriceps rehabilitation should begin within 2 weeks postoperatively.

Most patients have significant disability for a minimum of 4-6 months. The authors suggest that impact activities may be possible at 6 months, but patients should wait a full year before returning to full contact sports. If a nonunion becomes evident, autogenous bone grafting is usually indicated, usually before 1 year has passed since the index procedure, to avoid hardware failure.



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