Wear of Alumina-on-Alumina Total Hip Arthroplasties at a Mean 11-Year Followup

Abstract

The surface topography of 11 alumina-on-alumina hip arthroplasties retrieved for aseptic loosening at a mean 11-year followup was investigated. Macroscopic wear was assessed using a coordinate measuring machine. Microscopic wear features were evaluated by Talysurf analysis. Scanning electron microscopy was used to look at the alumina microstructure. Components were classified into three groups: (1) low wear with no sign of wear and average arithmetic roughness values below 0.05 microm; (2) stripe wear with a visible oblong worn area on the femoral heads and penetration rates below 10 microm/year; and (3) severe wear with a visible loss of material on both components, showing total roughness values as much as 4 microm and maximum penetrations higher than 150 microm. Alumina quality assessed by grain size measurements and porosity percentages improved progressively from 1977 to 1988. This resulted in a correlated decrease of the microscopic wear magnitude. However, on a macroscopic scale, factors responsible for either a load increase (weight, young age, and male gender) or impairment in the load distribution over the component surfaces (large grain size, nonoptimal initial cup inclination, and cup migration and/or tilting) increased the penetration rates.