Patent ID: 8768674

Claim:
A computer-implemented method of preoperatively determining an optimized external shape of a prosthetic femoral hip stem having a proximal and a distal segment as well as an intermediate segment between them, the proximal and distal segments to be press-fitted with an intramedullary canal of a femur of a patient and the intermediate segment having a reduced cross section for injecting cement, for use in partial cementing hip replacement procedures and of a reamer for reaming a cavity in the femur of a patient for implanting the prosthetic femoral hip stem, the method comprising: a) setting an initial external shape of the prosthetic femoral hip stem based on a reconstructed femur anatomy of a patient; b) generating an associated initial reamer by negatively offsetting the initial external shape of the prosthetic femoral hip stem by a offset value δ; c) calculating contact stresses at an interface of the prosthetic femoral hip stem and the patient's femur when reamed by the initial reamer; and d) optimizing the offset value δ, so that the contact stresses are within a predetermined acceptable range for promotion of bone formation and osseointegration, by shrinking the prosthetic femoral hip stem and/or the reamer as required.