A multi-directional wear screening device and preliminary results of UHMWPE articulating against stainless steel

This paper describes the design of a pin on plate rig which has been modified to give multi-directional motion to the test pins, resulting in elliptical and quasi-elliptical wear paths. Such paths are closer to those seen in vivo by a femoral head articulating against an acetabular cup. The description of the rig is augmented by the results of a test of ultra high molecular weight polyethylene pins rubbing against stainless steel plates, with dilute bovine serum at 37 degreesC being used as the lubricant. With standard reciprocating motion, a mean wear factor of 0.085 x 10(-6) mm(3)/N m was found, but with multi-directional motion, the mean wear factor increased to 1.10 x 10(-6) mm(3)/N m, which is very similar to in vivo wear factors.