Functional Outcome and MR Imaging of Abductor Damage Following Antegrade Femoral Nailing With Different Entry Points: A Prospective Randomized Trial

Background:

This study has been designed to prospectively evaluate functional outcome and MR imaging of abductor damage following antegrade femoral nailing with different entry points

Recent developments in IM nailing of the femur have favoured the use of the greater trochanter as an entry site as opposed to using the "classical" piriformis fossa. With either technique, a persistent problem appears however to be the damage caused to muscle tissue during preparation of the femur and insertion of the nail. The recent development of femoral nails with an entry point lateral to both these sites offers the potential advantage of avoiding abductor muscle damage.

In several cadaver studies, authors state that a trochanteric entry point causes more damage than a piriformis entry, and that an even more lateral entry point causes even less damage to the abductor muscles compared to the classical piriformis fossa entry site. There is however, no prospective clinical study has specifically evaluated the condition of the abductor tendon and the amount of muscle damage after antegrade nailing in the treatment of femoral shaft fractures. The few clinical studies that have attempted to examine the functional outcome in patients undergoing IM nailing of femoral fractures have used general measurement tools (general functional clinical assessment, gross evaluation of gait) which do not reflect the state of the art at this time and which do not specifically assess gluteal muscle condition. To date, no published study has evaluated the integrity of the gluteus tendon, the damage to the surrounding tissues, and the functional outcome using validated scores. Moreover, no study has compared the "traditional" entry points to a lateral entry nail with this level of precision.

The standard of care for the treatment of femoral shaft fractures is the insertion of an intramedullary nail through the piriformis fossa. Following insertion of femoral IM nails, a number of studies have demonstrated excellent clinical and radiographic results with relatively few complications such as nonunion, malunion, or infection. Intraoperative difficulties with respect to rapid identification of the appropriate starting point have prompted the development of nails that use the greater trochanter as an entry site as opposed to using the "classical" piriformis fossa.