A multidirectional motion pin-on-disk wear test method for prosthetic joint materials.

A realistic pin-on-disk wear test method for prosthetic joint materials has been developed. The new method, called circularly translating pin-on-disk (CTPOD), yields wear rates and wear mechanisms similar to those observed in retrieved polyethylene acetabular cups. In the established methods, where a polyethylene specimen slides against a unidirectionally rotating, or reciprocating, metallic or ceramic counterface, the wear rate typically is two orders of magnitude too low. In the present study, also, the reciprocator gave negligible wear. In the CTPOD method, considerable wear occurs because the direction of sliding rotates relative to the polyethylene pin, hence, the molecular orientation effect of polyethylene is avoided.