Effect of Lubricant Protein Concentration on the Wear of Ultra-High Molecular Weight Polyethylene Sliding Against a CoCr Counterface

In the wear testing of prosthetic joints, the optimal lubricant protein concentration is disputed. The effect of protein concentration of calf serum based lubricant on the wear of ultra-high molecular weight polyethylene against CoCr was studied with a 12-station, circularly translating pin-on-disk device. The wear factor first steeply increased with increasing concentration, reached a peak at 10–20 mg/ml, and then slowly decreased. Below 20 mg/ml, the wear mechanisms were not entirely representative of clinical wear. Above this value, the morphology of the UHMWPE wear surface resembled that of retrieved cups. The results indicated that the concentration should not be below 20 mg/ml. The scope of this recommendation is discussed.