Fretting corrosion in orthopaedic alloys.

Fretting corrosion, a mechanical-chemical phenomenon, most often occurs at screwhead-plate countersink junctions of internal fixation devices. An apparatus was constructed which would simulate the conditions of fretting corrosion in vivo. Fretting corrosion was studied as a function of the number of cycles and the solution in which the fretting occurred. The solutions studied were 0.9% physiological saline and a saline plus 0.5% albumin solution. The implant materials tested were Co-Cr-Mo alloy, 316L stainless steel, and Ti-6A1-4V alloy. The results demonstrated that weight loss increased with the number of fretting cycles but reached a plateau where further weight loss was negligible. Co-Cr-Mo alloy showed less weight loss than 316L stainless steel at any number of cycles. Weight loss for Ti-6A1-4V alloy was similar to Co-Cr-Mo alloy although marked abrasion was noted. All of the materials showed a marked decrease in weight loss when tested in the saline plus albumin solution as compared to the saline only solution.