Fretting corrosion of fully cemented polished collarless tapered stems: the influence of PMMA bone cement

In order to investigate the effect PMMA bone cement chemistry has on the fretting corrosion of cemented femoral stems, a novel test setup with integrated electrochemistry was developed and conducted in part reference to ISO 7206-4:2010. Ultima TPS™ femoral stems were cemented into a specially prepared delrin moulds using a third generation cementing technique similar to the procedure used in-vivo. Three commercially available PMMA bone cements were tested in order to understand the role bone cement chemistry plays on the fretting-corrosion rates at the stem-cement interface. Each stem-cement component was then orientated and set in place using laboratory grade PMMA cement, immersed in 0.9% NaCl and subjected to 500,000 cycles of cyclic loading at 1. Hz. Intermittent Open Circuit Potential (OCP) and Linear Polarisation Resistance (LPR) measurements were conducted in order to assess the effect PMMA bone cement chemistry has on the localised dissolution of cemented femoral stems. Macroscopic observation and scanning electron microscopy with integrated energy dispersive X-ray analysis (SEM/EDX) was conducted in order to support the electrochemical findings.