A Biomechanincal Comparison of Passive Range of Thumb Motion After Different Surgical Procedures for Trapeziometacarpal Joint.

Partial or total trapeziectomy with or without tendon suspension are clinically used for patients with trapeziometacarpal (TMC) osteoarthritis. There is a lack of information regarding biomechanical data of passive range of thumb motion after surgical procedures. In this study, we used fresh frozen cadavers to compare the range of motion under normal thumb and under simulated surgical interventions.

Ten fresh frozen limb beyond the upper arm were fixed with steel wire, so that no movement other than the TMC joint could be made, leaving the skin intact. Position sensors were attached to the tip of the thumb, proximal base of the first metacarpal. Passive range of thumb motion was measured by pulling the thumb tip with a 50g weight every 30 degrees of circumduction. An electromagnetic tracking system measured the angular and positional displacement of the thumb. Range of motion were compared between normal and after simulated surgical interventions which include partial trapeziectomy with and without suspension, total trapeziectomy with and without suspension. Suspension was done using either Abductor Pollicis Longus (APL) tendon or suture material.

After partial trapeziectomy, the range of thumb tip motion did not increase significantly from normal. After total trapeziectomy, the range of tip motion was significantly increased. Additional suspension using suture material decreased thumb tip motion in both partial and total trapeziectomy, and suspension using APL tendon decreased thumb tip motion in total trapeziectomy. Overall, the range of thumb tip motion with suspension using suture material tended to be smaller than using APL tendon. After partial trapeziectomy with suspension by APL tendon and total trapeziectomy with suspension by suture material, the range of angular motion of thumb circumduction were similar to that of normal.

While partial trapeziectomy did not significantly affect the range of thumb circumduction motion, total trapeziectomy increased the range of thumb motion compared to normal. Both partial trapeziectomy with APL tendon suspension and total trapeziectomy with suture material suspension can reproduce physiological thumb circumduction motion.

Keywords: First CM joit, arthroplasty, arthrodesis, cadaver