Joint kinematics after thumb carpometacarpal joint reconstruction: an in vitro comparison of various constructs.

PURPOSE: Osteoarthritis (OA) of the thumb carpometacarpal (CMC) joint causes pain and limits thumb motion. Different surgical procedures exist to treat thumb CMC OA; however, kinematic analyses of thumb reconstructions are limited. The purpose of this study was to evaluate kinematic changes of the thumb CMC joint as the result of different thumb reconstruction procedures.

METHODS: Fifteen cadaveric forearms were prepared and instrumented with an electromagnetic tracking device to measure the motion of the thumb metacarpal with respect to the trapezium (thumb trapeziometacarpal joint). Kinematics of the intact thumb and the thumb after trapeziectomy under passive motion were recorded. Specimens then had joint reconstruction consisting of either a ligament reconstruction with tendon interposition (LRTI), Weilby arthroplasty, or Thompson arthroplasty. The kinematic data collection analysis was repeated. The radius of joint motion and 3-dimensional (3D) work area were calculated for each surgery and were used for statistical analysis.

RESULTS: The type of surgical treatment significantly affected the joint radius of motion and the 3D work area. The Thompson and LRTI techniques produced a larger joint radius of motion than the other techniques (Weilby technique and total trapezial resection) and was similar to that of the intact joint. The Weilby and LRTI techniques produced a 3D work area similar to those of the intact joint and trapeziectomy and was also larger than that of the Thompson reconstruction.

CONCLUSIONS: Kinematic analysis of the thumb CMC joint is effective in differentiating surgical treatments used for end-stage of OA. Only the LRTI reconstruction produced a joint radius of motion and a 3D work area similar to the those of an intact thumb. Additional research is needed to define the optimal surgical techniques to treat the end-stage OA thumb CMC joint.