Finite element analysis of hip stem designs

A finite element analysis (FEA) was performed on six hip stem designs. The hip implant designs were then analyzed at forces ranging from 2.5 to 7 kN. These forces were selected because a typical gait cycle generates forces up to 6–7 times the body weight in the hip joint. The FEA results were compared for various stem designs assuming a rectangular cross-section. The design objective for a hip stem is to have a low stress, displacement, and wear at a very high fatigue life. The analysis performed in this paper may aid also in the fatigue testing of implants and/or base the designs for tested materials at a suitable fatigue life. Subsequently, the stems that had the highest stress and displacement models were then optimized for a lower stress and displacement combination. The cross-section that comprised a circle in the medial end and a square at the lateral end was found to provide suitable design characteristics. Fatigue and wear analyses were performed assuming that the implants were made of metal and polyethylene liner.