Subtrochanteric Femoral Fractures: Is a Nail or Plate Better?

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Chapter 61 Subtrochanteric Femoral Fractures: Is a Nail or Plate Better?

Subtrochanteric fractures remain a problematic fracture for treatment because of the local biomechanics, deforming forces of the attached musculature, and fracture configuration. The combination of high-stress concentration in an area of dense, cortical, hypovascular bone results in a propensity for nonunion. The soft-tissue stripping from the fracture can be further exacerbated with surgical dissection, resulting in a greater risk for delayed union and nonunion.

The deforming forces of the muscular attachments on the fragments combined with the effect of weight bearing result in the typical deformity of varus, apex anterior angulation, shortening, and external rotation of the proximal fragment. When inadequately corrected, a significant malreduction can increase the stress on the implant, leading to further deformity and implant failure. If the implant selected has poor fixation, or if weight-bearing limits are not adhered to, delayed displacement, malunion, or nonunion are the usual results.

Several classification systems are currently in use, including the Russell–Taylor classification,¹ the Seinsheimer classification,² and the AO/OTA classification. Each has its own method of stratification and nomenclature; however, they have not been shown to be useful in predicting treatment and outcome.^3,⁴

The treatment principles are similar to other nonarticular long bone fractures of the lower extremity. These include preoperative optimization, including smoking cessation, preoperative planning, surgical positioning, operative reduction and fixation emphasizing soft-tissue preservation, and postoperative rehabilitation protocols.

OPTIONS

The question of whether subtrochanteric femur fractures are best treated with an intramedullary nail device or an extramedullary plate device has been long debated and studied.^5,⁶ Devices currently in use include cephalomedullary nails, with either a piriformis or trochanteric start, and fixed-angle plating implants including blade plates, sliding hip screws, and locking plates. The purpose of this review is to guide surgeons in selecting the appropriate implant for this potentially troublesome fracture based on the best available evidence.

EVIDENCE

No Level I studies were available comparing treatment options for subtrochanteric fractures. The available Level II studies focused on pertrochanteric fractures, but few stratified for a subtrochanteric fracture group and even fewer specifically analyzed data for this fracture. Most of the studies were underpowered to show significant differences. Both biomechanical and clinical studies are available. However, extrapolating biomechanical results to the clinical situation must be done with caution because the most stable implant in the laboratory may not necessarily be optimal in a biological sense.

The available Level III and IV case series describing the treatment results with individual implants noted impressive success rates up to 100% and complication rates as low as 0%.⁷^–¹¹ Although these studies may give some indication as to the success and pitfalls of various implants, they provide little help in guiding treatment considerations of one implant versus another.

Specific patient or fracture characteristics may limit the treatment options available. In patients with previous surgery or hardware distally in the femur, such as a total knee prosthesis,¹² with previous deformity, or in pediatric fractures with open proximal growth plates, a fixed-angle plate device may be preferred. In patients with a significant lateral soft-tissue injury, or with extensive comminution or a segmental injury extending down the femoral shaft, a cephalomedullary nail is less traumatic to the soft-tissue envelope. In the case of a pathologic fracture, a cephalomedullary nail treats the fracture and provides prophylactic support or fixation for distal lesions.¹³ It would be difficult to produce randomized trials for each potential scenario comparing treatment strategy, and the level of evidence in this regard is therefore limited to Level V (expert opinion).

Biomechanics

The ideal fracture fixation device would be able to withstand the physiologic loads of postoperative rehabilitation. Typically, to stand in single-leg stance would axially load the femur with 750 N; however, walking or other activities of daily living would generate three to seven times that load.

Tencer and colleagues ¹⁴ compared seven devices in a cadaveric subtrochanteric fracture model tested in axial loading and found that the plate devices (compression hip screw and AO angled blade plate) failed between 1100 and 1500 N compared with a locked nail at 3000 N.

In a cadaveric study by Haynes and coworkers,¹⁵ the short Gamma nail (GN) was tested against the dynamic hip screw (DHS) in an osteotomized proximal femur simulating a subtrochanteric fracture with intertrochanteric extension. The authors found that in the harder bone model, the GN had a failure load of 5761 N versus the DHS with a failure load of 4660 N in axial loading. In the soft bone model, the failure loads were 5725 N for the GN and 3225 N for the DHS. The modes of failure were fractures of the femoral shaft around the distal locking screws for the GN, and lateral plate and screw pullout with the DHS.

It can be concluded from these and other similar studies that intramedullary devices are able to withstand greater axial loads than plate devices in unstable subtrochanteric fractures with medial comminution. The effect of nonaxial muscular forces on the fragments and construct stiffness may be a factor in the development of a delayed union or nonunion; however, the differences between implants in this regard have not been adequately reported in the literature.