A comparison of different methods in predicting static pressure distribution in articulating joints.

Pressure distribution along the contact surface of an articulating joint model was analyzed using different numerical and analytical methods: a discrete rigid element method [rigid-body-spring-model (RBSM)], the finite element method (FEM), a simplified elasticity solution (SES) and the modified Hertzian (MH) theory. The FEM and MH methods modeled joints interposed with elastic layers, while the RBSM and SES methods assumed a simplified joint with a rigid convex indenter on an elastic concave surface. Results for an axisymmetric joint model indicate that all of these methods predict similar pressure distributions on joint surfaces. In non-axisymmetric deformation mode, the RBSM method and FEM calculation showed good agreement in contact pressure prediction. Compared to the other three methods, the RBSM is relatively simple and effective in predicting joint contact pressure under symmetric and non-symmetric loading. The computational efficiency of the RBSM method is particularly attractive for pre-operative planning of reconstructive surgical procedures in orthopaedics in which geometric changes dictate the eventual outcome of the surgery.