Definition of Subtrochanteric Fractures
Various descriptions have been provided for what constitutes a subtrochanteric femur fracture. One commonly accepted definition is that it includes fractures which involve the lesser trochanter and extend distally up to 5 cm. Other definitions include fractures from the lesser trochanter to the junction of the proximal and middle third of the femur. The fracture may also include various proximal extensions.1
While several classification systems were developed for subtrochanteric femur fractures, the system proposed by Russell and Taylor (Table) has probably seen the greatest popularity (Slide 1). This classification system focuses on the integrity of the piriformis fossa and the practicality of using a piriformis entry intramedullary nail for fixation of the fracture. Type I fractures do not have extension into the piriformis fossa; type II fractures involve extension into the piriformis fossa.
Table. Russell-Taylor classification of subtrochanteric fractures.
|Involved in fracture
Each of these categories is subcategorized into two groups. In type IA, the lesser trochanter is intact, and these patterns can be fixed with a standard antegrade intramedullary nail. In type IB patterns, there is a fracture involving the lesser trochanter. A standard antegrade nail is not feasible in this pattern because the proximal locking screw cannot achieve purchase in the lesser trochanter. Treatment of this pattern generally requires a cephalomedullary nail that has a screw, or screws, which are positioned in the femoral neck and head. Alternatively, plating with a blade plate, a 95º sliding hip screw, or a locking proximal femur plate may be used.
The type II fractures are also subdivided into two categories. In type IIA patterns, there is no significant comminution of the lesser trochanter. While in type IIB patterns, there is comminution of the greater trochanter along with loss of the medial femoral cortex, including the lesser trochanter. Because of the involvement of the piriformis, most surgeons have avoided the use of a piriformis entry nail in these two patterns of fractures and traditionally have relied on some form of plate stabilization.
Complications Associated with Subtrochanteric Fractures
Subtrochanteric fractures can pose challenges in reduction due to the muscle attachments proximal and distal to the fragment. The gluteus medius and gluteus minimus attach to the greater trochanter and abduct the proximal fragment. The iliopsoas attaches to the lesser trochanter, flexing and externally rotating the proximal fragment. The short external rotators (piriformis, superior and inferior gemellus) and the obturator internus also cause external rotation of the proximal fragment. The adductors attaching distally result in varus and shortening.
Closed reduction of the fracture in the supine position may require the use of a Schantz pin placed in the proximal fragment to counteract the flexion force. Even when performing an open reduction, correction of the flexion deformity of the proximal fragment can be difficult. Reduction can often be more easily achieved in the lateral position, wherein the distal fragment can be flexed up until it aligns with the proximal fragment.
The subtrochanteric femur is a region of high stress, placing high demands on implants used for fixation. There are high compressive forces medially and high tensile forces laterally. When there is medial comminution, the implant used for fixation is subjected to a high bending load.
Subtrochanteric fractures are generally slower to heal than intertrochanteric fractures. This slow rate of healing places additional demands on the implants.
Failure to obtain an adequate reduction or unnecessary periosteal and soft tissue stripping may lead to nonunion and hardware failure. Historically, adjunctive bone grafting was often used to avoid nonunions; however, contemporary indirect reduction techniques and appropriate soft tissue handling usually results in good outcomes without the need for bone grafting.2
95º blade plate
Prior to the development of reconstruction-type cephalomedullary nails, the 95º blade was the commonly recommended implant for the fixation of many subtrochanteric fractures (Slide 2). The need to precisely align the cutting blade in three planes makes this implant technically challenging.
Yoo and colleagues3 reported on 38 patients with subtrochanteric or reverse obliquity-type fractures treated with the 95° blade plate. Union occurred at an average of 19 weeks. Complications included one nonunion and one hardware failure.
95º condylar screw
The 95º condylar screw, based on the two-part design of the dynamic hip screw, was developed to decrease the difficulty of implant insertion (Slide 3). Pai4 reported on 16 subtrochanteric fractures with greater trochanteric extension treated using the AO dynamic condylar screw (DCS) implant. Indirect reduction was used to avoid the need for bone grafting. The overall union rate was 93.7% (15 of 16) with one implant failure occurring following repeat trauma.
135º Dynamic/Sliding Hip Screw
The 135º sliding hip screw was designed for use in intertrochanteric hip fractures. Its use in subtrochanteric fractures can be successful, but additional periosteal disruption is necessary for reduction and fixation may lead to healing complications. Additionally, the proximal fragment may rotate about the single proximal compression screw.
The use of the 135º dynamic or sliding hip screw is specifically problematic in reverse oblique fracture patterns. In a retrospective study of reverse oblique fractures, loss of fixation was seen in 56% (9 of 16) treated with a 135º dynamic or sliding hip screw, compared with 13% (2 of 16) treated with a 95º blade plate.5
Locking proximal femur plate
Development of locking plate technology has provided improved mechanical stability of plate fixation. The locking proximal femur plate was designed as an alternative to the blade plate for subtrochanteric fractures (Slide 4). In a case report, Hasenboehler and colleagues6 have shown successful healing in a young patient who sustained a comminuted subtrochanteric femur fracture as a result of a high-velocity gunshot wound.
Cephalomedullary reconstruction nail
French and Tornetta7 reported on the use of a cephalomedullary nail for the treatment of 45 Russell-Taylor type IB subtrochanteric fractures. All patients achieved union, but 61% were noted to be reduced in some varus (5º to 15º). They reported a 13.5% rate of intraoperative complication and one hardware failure in a patient who began weight bearing prematurely. While emphasizing the importance of careful intraoperative technique, they suggested that an interlocking cephalomedullary nail may be the implant of choice for stabilization of Russell-Taylor type 1B fractures.
Trochanteric entry nail
Trochanteric entry nails have an apex medial-proximal bend that allows insertion in the greater trochanter rather than the piriformis fossa. Similar to cephalomedullary reconstruction nails, most trochanteric entry nails provide cephalomedullary directed screws or blades that engage the femoral head and neck (Slide 5).
Several studies have reported successful outcomes using trochanteric entry nails for intertrochanteric and subtrochanteric fracture patterns.8,9,10
Robinson and colleagues9 reported on the treatment of 302 low-energy subtrochanteric femur fractures treated with a long Gamma nail (Stryker, Kalamazoo, MI). They reported an 8.9% reoperation rate for implant or fracture related complications. Their patient population was primarily elderly, with a median age of 78.5 years. They noted a 24.5% 1-year mortality rate, similar to other studies of elderly patients sustaining hip fractures.
Starr and colleagues10 compared trochanteric entry vs a piriformis entry nail in a small series of younger patients sustaining high-energy proximal femur fractures. They found no difference in the surgeons’ perceived ease of reduction, surgical time, blood loss, or malunion rates.
Delayed union or nonunion is more common in subtrochanteric femur fractures than in diaphyseal femur fractures. Limited contact surface area, decreased vascularity, and high mechanical stresses have been identified as the reason for impaired healing.1
While modern implants have improved mechanical properties, loss of fixation and implant failure can occur following a subtrochanteric femur fracture due to the high stresses and prolonged duration of healing.
Complications commonly seen following other lower extremity fractures, such as deep venous thrombosis and wound infection appear to occur with a similar frequency in subtrochanteric femur fractures.
- Bedi A, Toan Le T. Subtrochanteric femur fractures. Orthop Clin North Am. 2004; 35:473-483.
- Lundy DW. Subtrochanteric femoral fractures. J Am Acad Orthop Surg. 2007; 15:663-671.
- Yoo MC, Cho YJ, Kim KI, Khairuddin M, Chun YS. Treatment of unstable peritrochanteric femoral fractures using a 95º-angled blade plate. J Orthop Trauma. 2005; 19:687-692.
- Pai CH. Dynamic Condylar Screw for subtrochanteric femur fractures with greater trochanteric extension. J Orthop Trauma.1996; 10:317-322.
- Haidukewych GJ, Israel TA, Berry DJ. Reverse obliquity fractures of the intertrochanteric region of the femur. J Bone Joint Surg Am. 2001; 83:643-650.
- Hasenboehler EA, Agudelo JF, Morgan SJ, Smith WR, Hak DJ, Stahel PF. Treatment of complex proximal femoral fractures with the proximal femur locking compression plate. Orthopedics. 2007; 30:618-623.
- French B, Tornetta P. Use of an interlocked cephalomedullary nail for subtrochanteric fracture stabilization. Clin Orthop. 1998; 348:95-100.
- Barquet A, Francescoli L, Rienzi D, Lopez L. Intertrochanteric-subtrochanteric fractures: Treatment with the long Gamma nail. J Orthop Trauma. 200l; 14:324-328.
- Robinson CM, Houshian S, Khan LAK. Trochanteric-entry long cephalomedullary nailing of subtrochanteric fractures caused by low-energy trauma. J Bone Joint Surg Am. 2005; 87:2217-2226.
- Starr AJ, Hay MT, Reinert CM, Borer DS, Christensen KC. Cephalomedullary nails in the treatment of high-energy proximal femur fractures in young patients: A prospective, randomized comparison of trochanteric versus piriformis fossa entry portal. J Orthop Trauma. 2006; 20:240-246.