Entry sites for antegrade femoral nailing.

Dissections on 42 anatomic specimen hips were performed to study proximal femoral anatomy as it pertains to entry sites for intramedullary nailing. The precise relationships of muscle insertions on the greater trochanter were documented, as were the boundaries of the digital fossa. Measurements of trochanteric bony anatomy were made on a separate group of 30 dry bone unpaired proximal femora. Finally, possible clinical insertion sites were studied radiographically by placing a series of guidewires at various locations in the proximal femur. Two areas tended to align well with the longitudinal axis of the proximal intramedullary canal: the digital fossa, which is the site of the insertion of the obturator externus; and the posterior aspect of the superior border of the trochanter. This second area is the tip of the trochanter posterior to the piriformis fossa. This study suggests that either location may be suitable for an insertion point for intramedullary nailing. Precise sagittal plane localization of the entry site, which can be made on lateral views with an image intensifier, is recommended.