Comparison of contact mechanics between a total hip replacement and a hip resurfacing with a metal-on-metal articulation

The finite element method was employed in this study to compare the contact mechanics at the bearing surfaces between a metal-on-metal hip resurfacing prosthesis and a total hip replacement with a similar bearing combination. The hip resurfacing prosthesis was implanted and modelled in a full three-dimensional pelvic and femoral bone. A significant reduction in the predicted contact pressure by over 53 per cent as well as a corresponding increase in the contact area by approximately 220 per cent was found in the hip resurfacing prosthesis, in comparison to the total hip replacement. The reduced contact pressure and increased contact area in the hip resurfacing system were due to the combination of the larger bearing size and increased elasticity from the metallic cup and the underlying bone support. The hip resurfacing prosthesis may therefore offer a significant improvement in the tribology at the metallic bearing surfaces, thus offering a potential advantage in terms of long-term clinical success over current total hip replacements with reported survivorships over 20 years.