Tribology of alternative bearings.
The tribological performance and biological activity of the wear debris produced has been compared for highly cross-linked polyethylene, ceramic-on-ceramic, metal-on-metal, and modified metal bearings in a series of in vitro studies from a single laboratory. The functional lifetime demand of young and active patients is 10-fold greater than the estimated functional lifetime of traditional polyethylene. There is considerable interest in using larger diameter heads in these high demand patients. Highly cross-linked polyethylene show a four-fold reduction in functional biological activity. Ceramic-on-ceramic bearings have the lowest wear rates and least reactive wear debris. The functional biological activity is 20-fold lower than with highly cross-linked polyethylene. Hence, ceramic-on-ceramic bearings address the tribological lifetime demand of highly active patients. Metal-on-metal bearings have substantially lower wear rates than highly cross-linked polyethylene and wear decreases with head diameter. Bedding in wear is also lower with reduced radial clearance. Differential hardness ceramic-on-metal bearings and the application of ceramic-like coatings reduce metal wear and ion levels.
Fisher
John
J
Institute of Medical and Biological Engineering, University of Leeds, Leeds, UK. J.fisher@leeds.ac.uk
Jin
Zhongmin
Z
Tipper
Joanne
J
Stone
Martin
M
Ingham
Eileen
E
D000537:Aluminum Oxide; D002858:Chromium Alloys; D006622:Hip Prosthesis; D006801:Humans; D066298:In Vitro Techniques; D010014:Osteolysis / Q000209:etiology; D011095:Polyethylenes; D011475:Prosthesis Failure; D013314:Stress, Mechanical
D002858:Chromium Alloys; D011095:Polyethylenes; D000537:Aluminum Oxide