Assessment of Titanium Alloy on Polyethylene Bearing Surfaces in Retrieved Uncemented Total Hip Replacements

Changes to the bearing surfaces of eighteen uncemented total hip replacements retrieved at revision surgery were assessed by three-dimensional binocular microscopy, Rank Taylor Hobson talysurf measurements, scanning electron microscopy, and X-ray dispersive analysis. Abrasions on the non-articular surface of the polyethylene cups were present. Bone particles were found in tracks in the bearing surfaces of both the titanium femoral heads and the polyethylene cups and were responsible for wear of these surfaces. Although the wear of the femoral heads appeared substantial to naked eye examination, the surface finish of these surfaces remained within the British ISO standards for titanium alloy when assessed by the methods used above. This study concluded that direct contact between polyethylene and bone should be avoided in total hip arthroplasty and that ‘third body’ wear from bone particles occurred in these uncemented prostheses. Both components of this type of implant should be replaced at revision surgery and titanium should be avoided as a bearing surface in hip arthroplasty. Present methods of assessing the surface finish of titanium should be re-evaluated and more reliable ones considered.