The effect of the surface finish of alumina and stainless steel on the wear rate of UHMW polyethylene.

The effect of the surface finish of medical grade alumina and stainless steel on the wear rate of ultra-high molecular weight (UHMW) polyethylene was studied in a six station pin-on-plate wear screening device using bovine serum as lubricant. The wear rate decreased as the surface finish of alumina improved from 0.10 to 0.015 micron Ra, with no evidence of an increasing wear rate below a particular value of surface finish. Tests with surgical grade stainless steel showed a similar polyethylene wear rate around the 0.025 micron Ra level, but there was evidence of a higher wear rate with stainless steel than with alumina between approx. 0.035 and 0.075 micron Ra.