Did wear simulator testing indicate biotribological risk for the ASR hip implant systems prior to market release...

The DePuy ASR hip implant systems had exceptionally high Cumulative Percent Revision compared with other implants in Australia. This was likely to be the case worldwide and thus the ASR hip implant systems were voluntarily withdrawn by DePuy on August 24, 2010. To avoid such debacles in future implant systems, it is instructive for biotribologists to examine the warnings provided by hip wear simulator testing prior to market release circa 2004. The ASR hip implants had metal-on-metal bearings that had shown some success in other designs. Based on hip wear simulator studies of these designs (mostly having 28 mm diameter heads), a Safe Zone for Wear Rates versus Implantation Time could be defined. However, some of the earlier metal-on-metal designs were wear simulator tested under some harsher clinically relevant conditions. They missed the Safe Zone thus confirming a biotribological risk for ASR hip implant systems. Subsequent analysis after market release of the ASR implants confirmed that the risk had been underestimated. Biotribological risk for new implant designs should be examined rigorously prior to market release.