Hip implant stem interfacial motion, a finite element analysis

A key factor in press fit hip implant fixation is the amount of interfacial motion between implant stem and the femur. A finite element analysis of hip implant stem designs was performed to determine the effect on stem interfacial motion. Implants of distinct cross section and stem profile were analysed. Implant material property effects were studied by analysing cobalt chromium (CoCr), stainless steel (SS316L), and titanium alloy (Ti 6Al-4V) implants. Each implant was subjected to a static loading simulating the weight of an average US male (189 lb) taking a step forward. Study results showed that implant cross section played a role in interfacial motion amounts. Ti 6Al-4V showed the greatest difference in implant interfacial motion as compared to SS316L and CoCr. Continued design and development of implant stems resistant to interfacial motion is needed.