This research initiation grant will develop a computer graphics system to analyze the potential outcome of hip replacement surgery. The thrust of the work is to incorporate a geometric model of a hip prosthesis into a model of the human lower limb and to determine how the prosthesis design and surgical procedure affect post-surgical hip muscle strength. The project emphasizes general principles rather than the planning of surgery for specific individuals. The research is expected to provide an interactive system that is useful for the planning of surgery and for teaching the biomechanical principles of surgical procedures.