Thumb Carpometacarpal Arthroplasty with Dynamic Suspension Sling Using Extensor Carpi Radialis Tendon

Background: Despite various treatment methods, complications are reported with ligament reconstruction for thumb carpometacarpal (CMC) arthropathy, such as proximal migration, dorsal subluxation of the first metacarpal base, and hyperextension of the first CMC joint. The flexor carpi radialis (FCR) tendon is, in some cases, too thin to maintain suspension on the first metacarpophalangeal (MCP) joint. We used one-half of the extensor carpi radialis longus (ECRL) tendon instead of the FCR tendon, and compared this method with conventional reconstruction using the FCR tendon. Methods: The procedures were performed during 12 thumb CMC arthropathies. One-half of the ECRL tendon was passed and then wrapped around the intact FCR tendon several times for 6 cases (ECRL group). One-half of the FCR tendon was passed for 6 cases (FCR group). On radiography, we compared the thumb to index finger metacarpal angle (M1M2) and the first MCP angle (P1M1) between groups. Grip strength, pinch strength, and DASH score were also evaluated up to 2 years post-surgery. Results: In the ECRL group, M1M2 and P1M1 1 year post-surgery showed significant improvements compared to those before surgery; they showed no significant difference in the FCR group, although they achieved a peak at 3 months post-surgery in both groups. Both groups showed improvements in other parameters from 3 months to 1 year post-surgery. Conclusions: Postoperative progression of hyperextension of the first CMC joint was significantly reduced in the ECRL group. The ECRL tendon is thicker than the FCR tendon. In addition, the insertion site of the ECRL tendon is at the dorsal side of the second metacarpal, and the tendon can extend from the dorsal side to the volar side to stabilize the first metacarpal. Thumb CMC arthroplasty using one-half of the ECRL tendon is a useful reconstruction method.