Trapeziometacarpal Joint: A Mechanical Explanation of Total Prosthesis Failures

Abstract

Total prosthesis, which preserves strength and respects trapeziometacarpal (TMC) joint range of motion, is a surgical option considered for the TMC joint replacement. With the usual ball-and-socket design, patients obtain faster pain relief, stronger grip function, and shorter convalescence than with trapeziectomy. However, prostheses currently used have led to various early complications, especially in active and young patients. Revisions are most often due to the loosening of the trapezium cup and of the metacarpal stem and to the luxation of the first metacarpal bone. The short lifespan of these devices suggests the difficulty of designing a prosthesis that respects the complex anatomy and motions of the TMC joint. Early implant failure may reflect the fact that the current devices do not exactly replicate the true kinematics. The aim of this chapter will be to shed light mechanical explanations for TMC prosthesis failures in regard to the complex kinematics of the joint.