Wear Simulation of Alumina-on-Alumina Prosthetic Hip Joints Using a Multidirectional Motion Pin-on-Disk Device

The wear of a state-of-the-art implant alumina against itself was studied with a circularly translating pin-on-disk (CTPOD) device, a wear simulator for prosthetic hip joint materials. The direction of sliding changed continually relative to the pin, preventing erroneous uniaxial grooving typical of ordinary pin-on-disk devices. The dominating wear mechanism was mild abrasion manifested as a relieflike surface, which agreed with clinical findings. The wear factor ranged from 1 × 10⁻⁸ to 6 × 10⁻⁸ mm³/(N·m). The CTPOD device, validated earlier for ultrahigh molecular weight polyethylene, was shown to be the first simple wear test device to produce wear similar to that known to occur clinically in alumina-on-alumina total hip prostheses.