Polymerizing Bone Cement can Roughen a Polyethylene Bearing Surface on Total Hip Replacement – A Surface Analysis

The tribological behaviour of the bearing surface in hip arthroplasty is greatly influenced by its surface roughness. During cemented hip arthroplasty, bone cement may contaminate the bearing surface. Hence, the aim of this study was to investigate the effect of cement polymerization on a highly cross-linked polyethylene(HCLP) bearing surface as any process influences the surface roughness of the bearing surface can have potential long term effect on the wear rate. Three new HCLP liners were used. A map of the surface topography of each liner was obtained using a white light interferometric microscope at five different locations in accordance with the standard BSEN ISO 4288:1998. Bone cement was then applied to the bearing surface and allowed to polymerise, then removed and irrigated with saline. The surface roughness measurement procedure was repeated again for all samples. The Ra results showed a 21% increase in mean surface roughness after cement contamination (p=0.01). The average Ra value pre-contamination was 190 nm while post-contamination was 230 nm. There were also changes in the surface topography observed with 3D surface mapping. Our study indicates that bone cement contamination of the HCLP surface can significantly increase its surface roughness and alter its surface topography. Surgeons should be aware of this potentially serious effect on the bearing and be vigilant to avoid bone cement contamination during arthroplasty surgery.