Surface roughness of femoral head prostheses after dislocation.

The effects of damaged femoral heads on long-term wear in total hip arthroplasties are not well known. In the study reported here, we compared the surface roughness of dislocated femoral heads, retrieved at time of revision, with that of heads revised for reasons other than dislocation. The dislocated heads, including 6 cobalt-chrome (Co-Cr), 2 oxidized zirconium, and 2 alumina (ceramic) heads, were compared with nondislocated Co-Cr and ceramic heads. Scratch marks on the dislocated Co-Cr and alumina heads were considerably smaller and shallow than those on the dislocated oxidized zirconium heads. Mean surface roughness of the dislocated heads was 368 nm (Co-Cr), 376 nm (alumina), and 2137 nm (oxidized zirconium). On the contrary, the mean surface roughness for nondislocated Co-Cr and alumina heads was 307.44 nm (outlier excluded) and 138.8 nm, respectively. Our data suggest that increased surface damage and roughness can occur after dislocation.