An examination of one-piece metacarpophalangeal joint implants using finite element analysis.

Abstract

Reconstruction of the rheumatoid metacarpophalangeal (MCP) joint is generally achieved by means of implantation of a hinged silastic prosthesis. These implants reduce the pain in joint and restore some degree of mobility. However, they are prone to failure after a relatively short life-span. In this study, two popular designs of MCP implant, the Swanson and the Sutter, were compared by means of three-dimensional finite element analysis. The aim was to examine how the differing geometry effected their relative stiffness as replacement joints, and whether they were inherently prone to high stress concentrations during flexion. Although the Swanson design implant exhibited relatively greater resistance to flexion, both designs showed regions of high stress concentration and it was noted that neither was without its limitations. The use of the finite element technique was found to be an excellent way to provide preliminary design evaluation information, allowing further evolution before clinical trials.