Hip Fractures: Current Review of Treatment and Management

Daniel C. Kim, MD, MS; Michael W. Honeycutt, MD; John T. Riehl, MD

Disclosures

Curr Orthop Pract. 2019;30(4):385-394. 

In This Article

Subtrochanteric Femoral Fracture

Introduction

Subtrochanteric (ST) fractures are defined as proximal femoral fractures occurring below the IT region and within 5 cm of the lesser trochanter of the femur. These fractures have a bimodal distribution occurring in young patients from high-energy trauma and in older patients from low-energy, osteoporotic mechanisms.[57] They also occur commonly in patients undergoing bisphosphonate therapy for osteoporosis.[58] ST fractures are challenging in reduction and fixation because the primarily flared cortical bone results in high rates of implant failure, nonunion, and malunion.[59–62]

Anatomy

The ST portion of the femur is composed of thick cortical bone in the normal and healthy physiologic state that does not fracture from low-energy mechanisms. Following Wolff's law of bone formation under mechanical stress, the medial side of this region withstands compressive forces of up 1,200 lb/in2 in a 200-lb male.[63] This high stress concentration has led to high rates of implant failures historically in ST fractures.

Understanding the deforming forces on a ST femoral fracture is crucial for reduction. The proximal fragment contains the lesser trochanter (LT) and greater trochanter (GT), which are the attachments for the iliopsoas (LT), short external rotators (GT), and gluteus minimus/medius (GT) muscles. These muscles displace the proximal fragment into flexion, external rotation, and abduction, respectively. The distal fragment contains the adductor tubercle and the linea aspera, which are the attachments for the adductor magnus and longus. These muscles will adduct the distal segment as well as shorten the deformed limb.

During reduction, care must be taken to avoid the medial circumflex artery that wraps around the LT as well as the sciatic nerve that runs posteromedial to the femur at this level.[12]

Classification

Classification systems for ST fractures are not commonly used. The Russell-Taylor classification can be used for diagnosis and prognosis; it is based on involvement of the LT and fracture extension into the piriformis fossa, which have implications for fracture fixation. Fracture patterns may vary from simple with good cortical contact to comminuted with bone loss.[64]

Treatment

There are two main methods of fixation of ST fractures, intramedullary (IM) implants versus extramedullary implants. IM implants include antegrade statically locked nails, CMN and recon nails, while extramedullary implants include a fixed-angle blade plate or a proximal femoral locking plate.[65]

CMN provide the advantage of a more central longitudinal position (reduced lever arm) to counter bending forces from axial load.[66] IM nails also allow for immediate weight bearing as they are load-sharing constructs. Insertion of IM nails is a technique familiar to most orthopaedic surgeons, and the percutaneous technique allows for reduced blood loss, decreased operative time, and reduced hospital stay compared to open fixation with a blade plate.[67] Due to modern design advantages and increased efficiency of technique, IM nails have become the gold standard for treatment of most ST fractures. CMN with large lag screws are avoided in younger patients in order to prevent removal of a large portion of bone from the femoral neck. When fixation into the femoral head is necessary in younger patients with ST fractures, a recon nail with two smaller screws into the head is therefore preferred.

Fixed-angle plates allow for minimal bone removal and indirect reduction through the plate; however, they are technically challenging, do not allow for immediate weight bearing, and have a higher rate of complications. Forward et al.[68] demonstrated that CMN withstood greater load, more cycles of loading, and failed at a higher force than either proximal femoral locking plates or blade plates. When these constructs do fail, they invariably fail in varus malalignment.[59,69]

Reduction of ST femoral fractures may be performed closed; however, many require percutaneous or mini open adjunct techniques. The flexion and external rotation deformities must be corrected initially. Further reduction must be a stepwise approach with percutaneous approaches including clamps, Schanz pins, Cobb elevators, bone hooks, or ball spike pushers to maintain control of the short proximal segment (Figure 6).[70] Patient positioning can be either supine or lateral, and surgeon preference varies between a radiolucent flat table and fracture table. When treating ST fractures with an intramedullary device, close attention should be paid to ensure the starting point is not too far lateral to prevent varus malreduction.

Figure 6.

Percutaneous reduction maneuvers in a subtrochanteric femoral fracture using Schanz pin, bone hook, and reduction finger (A) and Schanz pin and clamp (B).

Postoperatively, the goal is early ambulation, as with most hip fractures, to prevent complications associated with prolonged bedrest. With fixed angle plating, relatively simple fracture patterns with good cortical contact and no trochanteric extension may be made weight bearing as tolerated immediately postoperatively, while unstable fractures should have protected weight bearing for several weeks. With a statically locked intramedullary device, weight bearing as tolerated can be allowed immediately postoperatively in these fractures. Union rates average around 10–12 wk, with longer periods for return to normal gait and prefracture level of activity.[71,72]

Current Controversies

Comparison of trochanteric versus piriformis entry IMN for fixation of ST fractures have demonstrated no difference in blood loss, duration of surgery, intraoperative complications, union rate, or hip function scores.[73] A trochanteric entry nail has the potential disadvantage of increased morbidity to the abductor insertion in comparison to the piriformis entry but may have less risk of displacing fractures that propagate into the piriformis fossa.[74] Varus malalignment is theoretically less likely with a straight piriformis entry nail versus a curved nail; however, studies have shown no significant difference.[73]

Recent studies have suggested percutaneous cerclage wiring in conjunction with IMN to be an effective and safe reduction tool for fixation of ST fractures.[75–77] No increase in reoperation rate or implant-related failure was noted in these observational studies, but concern remains among some regarding the restriction of blood supply and callus formation at the fracture site with cerclage wires.[78] Blood flow studies and high-quality controlled studies could be helpful to test the efficacy and safety of this construct.

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