FINITE ELEMENT APPROACH TO DESIGN OF MODULAR HIP IMPLANTS MINIMIZING FRETTING WEAR

Abstract

Total hip replacement is a commonly used technique for the treatment of degenerative joint diseases. Several design innovations are pursued to meet their growing clinical need. Modular hip implants have emerged to become a mainstay in design as these offer a large array of femoral offsets, length adjustment and greater stability. A major disadvantage of modular implants is that each interface becomes a potential site for corrosion, fretting and fatigue between mating surfaces, which eventually leads to mechanical-assisted crevice corrosion. Though experimental studies have revealed the role of different implant design or manufacturing factors that affect MACC, finite element simulation models developed so far factor in only a few design modification in order to improve implant life. The objective of this study is to investigate the effect of bulk porosity, surface roughness and strength of the bone at the implantation site on implant performance in terms of contact pressure, micromotion and wear depth. It is observed that a three times increase in surface roughness increases wear depth by 1.2 times, increases porosity by 120%, causes wear to change two-fold, while weaker bone shows appreciably higher wear. The findings of this study provide a comprehensive tool to design hip implant with reduced probability of failure.