Comparative analysis of two different types of alumina-alumina hip prosthesis retrieved for aseptic loosening

We compared and quantified the modes of failure and patterns of wear of 11 Mittelmeier and 11 Ceraver-Ostal retrieved alumina-alumina hip prostheses w ith reference to the corresponding clinical and radiological histories. Macroscopic wear was assessed using a three-dimensional co-ordinate measuri ng machine. Talysurf contacting profilometry was used to measure surface ro ughness on a microscopic scale and SEM to determine mechanisms of wear at t he submicron level. The components were classified into one of three categories of wear: low (n o visible/measurable wear), stripe (elliptical wear stripe on the heads and larger worn areas on the cups) and severe (macroscopic wear, large volumes of material lost). Overall, the volumetric wear of the alumina-alumina pro stheses was substantially less than the widely used metal and ceramic-on-po lyethylene combinations. By identifying and eliminating the factors which a ccelerate wear, it is expected that the lifetime of these devices can be fu rther increased.