The long-term wear of retrieved McKee-Farrar metal-on-metal total hip prostheses

Twenty-four cobalt-chrome alloy McKee-Farrar matching acetabular and femoral components were retrieved at revision total hip arthroplasty. The average time in situ was 16 years. Wear and loss of sphericity was very low. Polishing wear (type 1), fine abrasive (type 2), multidirectional dull abrasive (type 3), and unidirectional dull abrasive wear (type 4) of the articulating Surfaces were identified. The mean percent area of femoral heads occupied by types 2, 3, and 4 wear was 18%, 5%, and 2%, respectively. There was no association between the type and distribution of wear and the time in situ. impingement damage was evident on 9 implant pairs. The extent and types of wear described in this paper will be useful when analyzing, the patterns of surface damage of newer designs of metal-on-metal articulations.