The purpose of this study is to assess the functional outcomes in patients undergoing proximal femur resection and reconstruction with an endoprosthesis, based on the abductor muscle repair technique. The investigators hypothesize that those patients who receive reattachment of the abductors directly into the prosthesis will have better functional outcomes overall. Furthermore, the investigators plan to develop a simple, cost effective, and reproducible method to assess abductor function at clinical post-operative visits through plain radiographs.