Wear characteristics of ceramic-on-ceramic for hip endoprostheses

Femoral ball heads of aluminium oxide or zirconium oxide ceramics are used for total hip replacement. This application is based on their attractive tribological properties. Standard and state-of-the-art are femoral ball heads made of alumina (Al2O3) articulating against acetabular cups of polyethylene (PE-UHMW) and zirconia (Y-TZP) heads articulating against polyethylene cups. A very attractive wear couple is ceramic-on-ceramic. Some of the various ceramic combinations have been tested using the ring-on-disc method according to ISO 6474. The combination alumina/alumina was found to produce extremely low wear; catastrophic wear was found for the combinations alumina/Y-TZP and Y-TZP/Y-TZP.