Tip-Apex Distance as a Predictor of Failure Following Cephalo-Medullary Fixation for Unstable Fractures of the Proximal Femur

Current research has been unable to confirm that intramedullary fixation provides greater stability for unstable fracture configurations of the proximal femur than extra-medullary devices. We present a retrospective analysis of the outcome of proximal femoral fractures treated with the Proximal Femoral Nail (PFN, Synthes) with particular reference to implant position and adequacy of reduction. Between May 2002 and October 2004, 61 patients with low-energy unstable proximal femoral fractures underwent surgery at a mean 2.4 days. Mean age was 78 years, 74% were female. Four (6.9%) implants failed secondary to proximal cut out of the hip screw. All of the failures occurred in patients who had sustained AO/OTA type 31. A3 fractures. In patients with A3 fracture patterns, there is a significant relationship between increasing Tip-Apex distance (p = 0.023), varus mal-reduction (p = 0.038) and failure; 46% patients died within 12 months of surgery. The PFN is a satisfactory implant in the management of unstable proximal femoral fractures, however accurate reduction and implant position are essential to provide the best conditions for union and to prevent implant failure.