Comparative wear under different conditions of surface-engineered metal-on-metal bearings for total hip arthroplasty.

Metal-on-metal hip arthroplasties have demonstrated low wear rates. However, the ion release and toxicity of the metal wear particles remains a concern. Modifying the surface of metal bearings with thick chromium nitride (CrN) coatings has the potential to further reduce wear and ion release, and improve the biocompatibility of wear particles produced. The aim of this study was to investigate the application of surface engineering technology to modify metal-on-metal (MOM) bearings to reduce wear and improve the functional biocompatibility of metal-on-metal prostheses. CrN-on-CrN bearings had lower wear rates in comparison to metal-on-metal bearings, particularly under adverse loading conditions. CrN-on-CrN bearings produced similar nanometer-sized particles to metal-on-metal bearings, however, CrN wear particles were less cytotoxic when cocultured with macrophage and fibroblast cells.