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Background: In a cadaveric model, we evaluated thumb metacarpal subsidence, indicated by a decreased metacarpal-to-scaphoid distance, after 2 surgical procedures used to treat thumb carpometacarpal (CMC) osteoarthritis (OA): partial trapeziectomy with capsular interposition (PTCI), which involves removal of 2 mm of both the distal trapezium and base of the metacarpal; and total trapeziectomy with capsular interposition (TTCI). Methods: Nine matched pairs of cadaveric hands were randomly assigned to undergo either PTCI or TTCI. Preoperatively, physiologic forces were applied across the thumb CMC joint by loading 6 tendons, simulating lateral pinch. Anteroposterior radiographs were obtained, and the metacarpal-to-scaphoid distance on each image was estimated independently by 3 separate readers using customized software. A hand surgeon then performed the PTCI and TTCI procedures, and the measurements under loading were repeated. The results were assessed for interrater reliability. Mean values for metacarpal-to-scaphoid distance before and after the surgical procedures were compared. Results: Preoperatively, the metacarpal-to-scaphoid distance in the PTCI and TTCI groups was not significantly different. Postoperatively, metacarpal subsidence was significantly less in the PTCI group (17% compared with 34% for TTCI; P = .05). Conclusions: Metacarpal subsidence occurred after both PTCI and TTCI, but significantly less subsidence was observed after PTCI; thus, thumb length was better preserved. Previous research has shown an inverse correlation between maintenance of thumb length and overall Disabilities of the Arm, Shoulder, and Hand (DASH) score. A procedure for treating thumb CMC OA that preserves thumb length and minimizes disruption of stabilizing joint tissue may provide enhanced maintenance of thumb stability and improved patient outcomes.
Salas et al. (Fri,) studied this question.