Titanium based alloys are being considered as orthopaedic implants for a variety of reasons: excellent corrosion resistance, good ductility and formability, biocompatibility, high tensile strength, high fatigue strength, low density and most importantly low modulus of elasticity. The only undesirable feature of these alloys is their poor wear resistance. While Ti-6A1-4V has recently been introduced for construction of the femoral component in knee-joint systems, the questionable wear performance of the Ti-6A1-4V is a barrier for a more widespread acceptance of the alloy for this application. The results of the tests performed in the Phase 1 study clearly show that the ion implantation process is an effective method for improving the wear resistance of Ti-6A1-4V alloy for prosthesis and substantially reducing the wear of the mating ultra high molecular weight polyethelene(UHMWPE)surface on which it articulates. The objective of the present study is: to investigate the best choice of ion species; to identify the optimum ion beam parameters (energy, dose, etc); to charactertize the wear improvement of the implanted samples under realistic test conditions; to test biocompatibility of the implanted specimens to measure the corrosion resistance and fatigue improvement of the implanted samples; and finally to demonstrate the superior wear resistance of the ion implanted femoral components using the total knee joint simulators. The long-term goal of the project is to document the effectiveness of the ion implantation process on titanium orthopaedic devices and to provide all the necessary data for full scale commercialization.
