A quantitative analysis of bone support comparing cementless tapered and distal fixation total hip replacements.

The purpose of this study was to develop a technique to accurately assess cementless femoral stem-bone contact. Using this technique, differences in contact patterns between tapered (Synergy) and cylindrical distal fixation (Prodigy) cementless stems were explored. Femurs were prepared and the 2 types of femoral stems were implanted. After implantation, the femurs were imaged in a spiral computed tomography scanner and analyzed using novel custom-developed imaging software. This analysis used a geometric deformable-model UNIX-based software that determined bone-prosthesis contact area. The tapered stem features proximal, cancellous bone contact and a 3-point fixation pattern. The cylindrical distal fixation stem demonstrates cortical support in the distal aspect of the stem.