A comparison of canine and human UHMWPE acetabular component wear

The objective of this study is to compare the wear patterns and wear rates of ultra high molecular weight polyethylene in acetabular components used in human and canine total hip arthroplasty. This comparison may help elucidate both the appropriateness of the dog as an orthopaedic model for humans as well as the clinical performance of canine total hip arthroplasties. Twenty-nine postmortem retrieved and three revision retrieved canine acetabular components were analyzed. The volumetric wear rates in the canine postmortem retrievals of 6.9 mm3/year for modular (BioMedtrix) implants and 8.3 mm3/yr for monolithic (Richards) implants were considerably lower than those of 35.0 mm3/yr measured in human postmortem retrievals, reported using a similar measurement technique. The canine revision retrieval volumetric wear rate of 34.8 mm3/yr was significantly higher than postmortem rates, yet considerably lower than the reported retrieval rates of 62.0 mm3/yr seen in humans. These results may have negative implications for the use of the dog as an orthopaedic model for humans in total hip arthroplasty studies.