Volumetric assessment of material loss from retrieved cemented metal hip replacement stems

Abstract

The aim of this study was to investigate the scale of metallic wear debris generation at the cement-stem interface of polished cobalt-chrome implants. Thirty-one Zimmer CPT cemented femoral stems were retrieved; mean time in vivo was 77.8 months (range 38–97 months), with 70% (n=21) of the stems considered to be well-fixed at the time of revision surgery. Volumetric loss was measured using optical microscopy, with focus variation technology capable of 3D reproduction of the surfaces. The scale of loss was found to be pronounced (mean: 3.1mm3, 0.02–11.4mm3), with a mean rate of 0.5mm3/year (0.003–1.9mm3/year). These results demonstrate that material loss from the cement-stem interface is comparable to that of a taper interface, even in apparently well-fixed stems.