 Hip and knee replacement arthroplasty are profoundly successful operative interventions, however, some joint replacements do fail and the life expectancy of a hip or knee arthroplasty is finite Malchau et al. 1993, Knutson et al. 1994, Herberts et al. 1997, Garellick et al. 1998. This fact has largely been responsible for the continued development of new devices and techniques for joint arthroplasty surgery. Unfortunately, the introduction of new technologies and devices is not a benign process, and even subtle changes to existing implants can have a disastrous effect on patient outcome Sudmann et al. 1983, Herberts P. 1986, Ohlin et al. 1989, Wedderkopp et al. 1997, Howie et al. 1998, Nilsson et al. 1998. 