[Effect of prosthesis shaft coating on postoperative load bearing of the femur].

Stems and cups for total hip replacement (THR) must be coated with hydroxyapatite (HA), which enhances the osseo-integration of the implant. The aim of the present report was to investigate the basic influence of coating on the biomechanical situation, for example, the mechanical stress in the femur and at the femur-implant interface. Using the finite element method, three types of stems for THR were investigated: non-coated, completely HA-coated, and proximally HA-coated. All three stems were of the same design, and had identical material properties. In addition, all other conditions were identical. The results show that, in terms of the nature of the coating, the HA-coated stem is biomechanical superior to the non-coated stem, and the proximally coated stem is superior to the completely coated stem.