Finite element analysis of a novel design approach to resisting total hip dislocation

Objective. A new design concept has been developed to reduce the propensity for dislocation in total hip patients. The ability of this design to increase the stability of the hip joint is studied. Design. The new design involves a convex-curved acetabular lip, extending from the hemispherical articulating surface to the outer edge of the cup. The femoral component has a matching, reverse curve. Background. Dislocation is a continuing problem in total hip arthroplasty, a complication experienced by 2-11% of patients with primary surgeries, and much higher percentage of patients in revision series. Confounding factors and sources of variability in the clinical domain make it difficult to identify specific parameter influences. Methods. A three-dimensional nonlinear finite element model has been developed for the purpose of studying the dislocation event. We report the first use of this finite element model to analyze the potential for improving hip stability by a new total hip component design concept. Results. The results show that this new design achieves 28% more resisting moment build-up during dislocation, and has a higher range of motion from impingement to onset of subluxation. The new curved lip design also develops 50% less polyethylene von Mises stress in the impingement zone. Conclusions. This design has excellent potential for increasing the inherent stability of the total hip joint. (C) 1999 Elsevier Science Ltd. All rights reserved.