Extramedullary vs. Intramedullary Devices in the Treatment of Unstable Intertrochanteric Hip Fractures

Intertrochanteric hip fractures are common injuries in the elderly population. They often signify generalized physical deterioration. Operative management has become the standard of care to prevent life threatening complications and dates back to the 1940's. The design of implants has evolved significantly since then.

The sliding hip screw replaced static fixation of the femoral head in the 1950's. As a result of this improvement in design, failures have been reduced to 9-16%. The sliding hip screw allows for stable collapse of the femoral neck. This can lead to significant shortening of the proximal femur in comminuted fractures.

Current treatment modalities focus on obtaining a satisfactory union of the fracture, often at the expense of anatomical alignment. Severely comminuted fractures treated with a standard plate-hip-screw device thus commonly result in significant degrees of mal-union and shortening. In the past, implants designed to restore and maintain the anatomy of the hip have resulted in high failure rates with the implant breaking out of the femoral head. In the mid 1980's, recognition of this led to the development of various intramedullary devices for fixation of these fractures. The weight-bearing portion of the implant is therefore shifted medially, resulting in reduced lever forces on the implant and femur. Additionally, the IM device does not rely on fixation to the lateral cortex of the femur with screws. From a biomechanical standpoint, the intramedullary device has distinct advantages, as it is a load- sharing device more closely located to the axis of weight bearing than the plate-hip-screw device.

Advances in intramedullary designs have been promising, but the clinical results variable. The relatively high rate of fracture at the tip, specifically at the level of the locking bolts, has hampered the widespread popularity of intramedullary devices. Additionally, the large diameter of the proximal aspect of the implants required extensive reaming of the greater trochanter and partial detachment of the gluteus medius. This may lead to abductor weakness and a Trendelenburg gait. Some studies have found increased re-operation rates for these early hip-nail devices compared to the plate -hip-screw implant. Other studies have shown decreased blood loss and operative time with the nails. A meta-analysis of the literature favors the sliding hip screw design. Unfortunately, most studies focus on radiological failure rate rather than patient function and relate to the first generation of IM devices.

The newest generation of nails (like the IM studied here) has attempted to correct the shortcomings of earlier designs. The proximal aspect of the nail diameter is minimized. The distal locking screw is located far away from the distal end of the nail and the locking bolt is placed in an oblique fashion. Design alterations to the femoral head fixation portion of the nail by using a helical blade rather than a screw may improve fixation in the femoral head. These new designs seem to compare favorably in recent clinical tests. Early mobilization for patients with the intramedullary device (IM) seems to be better.