Influence of Bearing Couple, Lubricant and Swing Phase Load Conditions on the Friction of 28mm Hip Replacements

INTRODUCTION The majority of current artificial hip implants use a material combination of ultra-high molecular-weight polyethylene against metal or ceramic. However, it is well documented that the wear debris from these prostheses contributes to osteolysis and ultimate failure of the prosthesis, hence alternative materials have been sought, such as metalon-metal and ceramic-on-ceramic [1]. More recently, ceramic-on-metal bearing couples have been developed [2]. Metal-on-UHMWPE implants were first employed due to the low frictional properties of the UHMWPE material. Excessive frictional torque was cited as the cause of failure for first generation metal-onmetal implants [3]. However, it is generally accepted that the frictional torque generated in modern metal-on-metal implants would be insufficient to cause immediate mechanical failure. Nevertheless, friction studies provide a valuable indication of the tribological performance of a system. This study aimed to examine the effect of material, lubricant and swing phase load conditions on the friction of hip replacements.