0536 - the Effect of Radio-opacifiers in Bone Cement on an in Vivo Model of Aseptic Loosening

INTRODUCTION Aseptic loosening is the commonest cause of failure of total joint replacements. The pathogenesis of this process remains controversial but appears to involve prosthetic migration, joint fluid pressure and the host response to particulate wear debris. The Swedish Hip Registry has shown that the type of bone cement used effects the risk of revision for aseptic loosening. It has been suggested that this effect is mediated by the host response to the type of radio-opaque agent contained within bone cement particulate debris, as CMW, which contains barium sulphate (BaSO4) caused more bone resorption than Palacos, which contains zirconium dioxide (ZrO2), in an in vitro assay. Radiolucent bone cement particles caused less bone resorption than either. However, the proprietary bone cements differ in their chemical constituents by more than just the radio-opacifier they contain.