SEDL / STP / STP1346-EB / STP12835S

Wear Morphology of Metal-Metal Implants: Hip Simulator Tests Compared with Clinical Retrievals

Park, S-H
Assistant and Associate Professor, and Laboratory Manager, University of Southern California, Los Angeles, CA

McKellop, H
Assistant and Associate Professor, and Laboratory Manager, University of Southern California, Los Angeles, CA

Lu, B
Assistant and Associate Professor, and Laboratory Manager, University of Southern California, Los Angeles, CA

Chan, F
Ph.D. candidate, Jo Miller Orthopaedic Research Laboratory, McGill University, Montreal, Quebec

Chiesa, R
Politecnico di Milano,

Pages: 15    Published: Jan 1998

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Abstract

This study compared the bearing surfaces of modern-generation metal- metal implants worn in five different hip joint simulators and worn in vivo. Comparable wear morphology was found between in vitro and in vivo worn implants. The non-contact zones displayed fine residual scratches from the original polishing, and carbide bumps that were either rounded or irregular. In the main bearing zones, the polishing marks and third- body scratches were worn smooth. Moreover, there were flat-bottomed depressions, apparently carbides that had been dissolved below the level of surrounding matrix. Localized numerous micropits were found in the smoothly worn area on most of simulator tested specimens and on some of the retrieved implants. Surrounding the main wear zone was a transition zone containing dense third-body scratches, and thin deposits containing calcium phosphate. The comparable wear morphology suggested that in vitro wear simulators can provide an accurate model of the wear in vivo of modern-generation metal-metal total hip replacements.