Se. White et al., SIMULATED KNEE WEAR WITH COBALT-CHROMIUM AND OXIDIZED ZIRCONIUM KNEE FEMORAL COMPONENTS, Clinical orthopaedics and related research, (309), 1994, pp. 176-184
A knee simulator that mimics the plowing/rolling wear mechanisms of th
e knee was used to compare wear properties of cobalt chromium and oxid
ized zirconium femoral components. The simulator flexes and extends th
e knee so that the femoral component travels from 0 degrees to 30 degr
ees while applying axial loads from 130 to 1300 lb. Three oxidized zir
conium and 3 cobalt chromium femoral components were tested with 10-mm
tibial polyethylene components. The oxidized zirconium femoral compon
ents caused significantly less ultra high molecular weight polyethylen
e wear than cobalt chromium femoral components. Tibial inserts that we
re articulated against the cobalt chromium components had evidence of
scratching, burnishing, and delamination, but none of the surfaces tha
t were articulated against oxidized zirconium components had evidence
of delamination. Cobalt chromium surface roughness significantly incre
ased during the 2,000,000 cycle test, but oxidized zirconium surface r
oughness was not affected. Polyethylene wear was correlated to a signi
ficant degree with the surface roughness of the femoral components. Th
e improved wear characteristics of the ceramic articular surfaces can
be explained by the wettability of the ceramic surface, which minimize
d adhesive wear, and the resistance of the hard, ceramic surface to ro
ughening.