Metal-on-metal bearing in hip prosthesis generates 100-fold less wear debris than metal-on-polyethylene

Aseptic loosening due to osteolysis in total hip replacement has been relat ed to wear debris released from prosthetic components. Retrospective longte rm observations of patients with the metal-on-metal prosthesis has shown lo ng-term survivorship and good mechanical performance. Thus, the new and mod ified metal-on-metal prosthesis has been introduced on the market. Historic al clinical data from the 1st generation metal-on-metal hip prosthesis may not be relevant for the 2nd generation of metal-on-metal hip prosthesis. Th erefore, preclinical testing of the prosthesis must be conducted before cli nical evaluation. We assessed the tribological performance of the metal-on-metal prosthesis v ersus the metal-on-polyethylene prosthesis introduced on the market as Meta sul(TM) and Protasul(TM), respectively. In a 12-channel joint simulator, 6 metal-on-metal bearing and 3 metal on polyethylene prostheses were tested, with the same number of corresponding soak controls. The wear was assessed gravimetrically. The "steady-state" wear-rates from the metal-on-metal pros thesis were almost 100 times less than that from the metal-on-polyethylene prosthesis. The tribological wear performance of the metal-on-metal hip pro sthetic system is promising.