Charnley wear model for validation of hip simulators--ball diameter versus polytetrafluoroethylene and polyethylene wear.
Wear rates of polytetrafluoroethylene (PTFE) and polyethylene cups were compared in 9-channel and 12-channel simulators, using serum lubrication and gravimetric techniques for wear assessment. Cobalt-chromium (CoCr) and alumina ceramic femoral heads in 22-42 mm diameter range were used to validate simulator wear rates against clinical data. This was also the first study of three femoral head sizes evaluated concurrently in a simulator (with three replicate specimens) and also the first report in which any wear experiments were repeated. Fluid absorption artefacts were within +/-1 per cent of wear magnitude for PTFE and +/-8 per cent for polyethylene and were corrected for. Wear rates were linear as a function of test duration. Precision within each set of three cups was within +/-6 per cent. The wear rates from experiments repeated over 15 months were reproducible to within +/-24 per cent. However, the magnitudes of the simulator wear rates were not clinically accurate, the PTFE wear rates (2843 mm3/10(6) cycles; 22 mm diameter) were over three times higher than in vivo, the polyethylene 30 to 50 per cent on the low side (23 mm3/10(6) cycles; 22 mm diameter). Volumetric wear rate increased with respect to size of femoral head and a linearly increasing relationship of 7 8 per cent/mm was evident with respect to femoral head diameter for both PTFE and polyethylene. These data compared well with the clinical data.
Clarke
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Howard and Irene Peterson Tribology Laboratory, Loma Linda University Medical Center, California, United States of America.
Good
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Anissian
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Gustafson
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D000537:Aluminum Oxide; D001672:Biocompatible Materials; D002858:Chromium Alloys; D005270:Femur Head; D006622:Hip Prosthesis / Q000295:instrumentation*; D006801:Humans; D008153:Lubrication; D008422:Materials Testing; D008953:Models, Anatomic; D011095:Polyethylenes; D011138:Polytetrafluoroethylene; D011474:Prosthesis Design
D001672:Biocompatible Materials; D002858:Chromium Alloys; D011095:Polyethylenes; D011138:Polytetrafluoroethylene; D000537:Aluminum Oxide