Effect of nitrogen plasma-based ion implantation on joint prosthetic material

In total hip arthroplasty (THA), Ultra High Molecular Weight Polyethylene (UHMWPE) wear debris generated at the articular surface has been recognized as a long-term cause of loosening and failure of artificial hip joints due to osteolysis. The technique of ion implantation has been used to improve wear resistance of the metal femoral head. The Plasma-Based Ion Implantation (PBII) technique is more suitable for complex shaped implants such as femoral head and femoral prosthesis due to three-dimensional ion implantation effects. The effect of pulse voltage and cooling of the substrate of the PBII process for Co–Cr-based materials were examined in terms of wear resistance by the pin-on-disc wear test. The wear resistance of Co–Cr alloy with high nitrogen-ion implantation dose was superior to the untreated Co–Cr alloy. Their corrosion resistance has also been examined with an anodic polarization measurement. High dose and cooling of PBII process proved to be effective in enhancing corrosion resistance of Co–Cr alloy. In this study, it was confirmed that the improvement of wear and corrosion resistance of Co–Cr alloy modified by PBII, as well as high pulse voltage and cooling of the substrate for PBII were the most effective treatments.