Effect of acetabular cup position on the contact mechanics of ceramic-on-ceramic hip joint replacements

The importance of the position of an alumina acetabular cup in close contact with an alumina femoral head was examined in this study using the finite element method. The effects of a wide range of inclination angles from 45degrees to 84degrees and anteversion angles from 0degrees to 25degrees were investigated on the predicted contact mechanics at the articulating surfaces. For the range of implantation angles considered in this study, no edge contact was observed at the rim of the acetabular cup, and the effect of the acetabular cup position on the predicted maximum contact pressure was found to be very small (less than 10%). These findings suggest that the edge contact and associated stripe wear observed clinically in ceramic-on-ceramic hip implants should be related to other mechanisms such as micro-separation, rather than to the position of the acetabular cup directly.