Optimal Wear Performance of Ceramic-on-Ceramic Bearings for Total Hip Replacement

Abstract

Rigid-on-rigid ceramic bearings have been in continuous use since 1970. With the increased concerns over polyethylene (PE) wear debris promoting osteolysis, there has been a renewed interest in such Al2O3/Al2O3 combinations. In this in vitro study, the wear performance of Al2O3/Al2O3 combinations was compared to Al2O3/PE, using 28-mm Bioceram femoral heads and acetabular inlays with three combinations of diametral tolerances. Wear evaluation was performed in a multichannel hip simulator using physiological load-profiles and 90% bovine serum as the lubricant. At the short-term duration of 3.6 million cycles, approximately 3 years use in the patient, the Al2O3/Al2O3 wear rates were exceedingly low, at less than 0.03 mm3 per million cycles. In contrast, the Al2O3/PE combination produced 20.8 mm3 of polyethylene debris per million cycles. This represented over 600-times more wear debris than the Al2O3/Al2O3 combinations at this time interval. Thus, the relative wear performance of the Al2O3/Al2O3 was far superior to Al2O3/PE with serum lubrication. The simulator wear studies are continuing to 10 million cycles (10 years use in patient), to discriminate between the three diametral-tolerance groups for Al2O3/Al2O3 combinations and to confirm the relative volumetric wear performance relative to the standard Al2O3/PE combination.