Hip simulator wear comparison of metal-on-metal, ceramic-on-ceramic and crosslinked UHMWPE bearings

Alumina ceramic-on-crosslinked polyethylene (C-CLPE), metal-on-metal (M/M) and alumina-on-alumina ceramic (C/C) articulations are high performance, low wear options for hip replacement bearings. Our objective was to compare the hip joint simulator wear performance of these alternative bearing couples to each other and to a control bearing of standard ultra-high molecular weight polyethylene (UHMWPE). Contemporary hip joint simulators were used for wear testing. All components were tested at 1 Hz under a joint reaction profile (2450 N maximum) and 50% diluted alpha-calf serum lubrication. Standard lubricant replacement, specimen cleaning and wear loss measurement methods were followed. Crosslinked polyethylene (PE) showed a 10-fold reduction in wear over control UHMWPE liners, regardless of head size. M/M components showed a nine-fold reduction in wear over the control PE. Wear performance of the M/M bearings was non-linear and highly variable; one M/M sample had a wear rate similar to that of the PE controls. Wear rates for C-CLPE and C/C were far less variable than for M/M. C-CLPE bearing wear was more consistent than M/M, although both had similar average wear. C/C showed a consistent 500-fold wear reduction over control PE and a 50-fold reduction over M/M or C-CLPE.