Effect of Trapeziectomy on Carpal Stability.

Background: The scaphoid-trapezoid-trapezium (STT) articulation stabilizes the scaphoid and links the proximal and distal carpal rows. The purpose of the study was to determine whether trapezium excision in the treatment of trapeziometacarpal (TM) arthritis affects carpal stability. Methods: A retrospective chart and radiographic review was performed on all wrists that underwent trapeziectomy with suspensionplasty or ligament reconstruction, and tendon interposition for TM arthritis between 2004 and 2016. Radiographic outcome measures included the modified carpal height ratio (MCHR) and radioscaphoid (RS), radiolunate (RL), and scapholunate (SL) angles. Degenerative change at the TM and STT joints was classified according to the Eaton-Littler, and Knirk and Jupiter classification systems. Radiographic parameters were compared between preoperative and final follow-up time points. Results: A total of 122 wrists were included in the study with a mean follow-up of 3.5 years (range: 1.0-13.0 years). The mean RL (range: -2.2° ± 11.8° to -10.7° ± 16.5°) and RS angles (range: 52.6° ± 13.8° to 44.4° ± 17.8°) decreased significantly (<.001) without significant change in SL angle, indicating progressive lunate and scaphoid extension after trapeziectomy. The mean MCHR decreased significantly (range: 1.6 ± 0.1 to 1.5 ± 0.1) following trapeziectomy, indicating progressive carpal collapse. Progressive scaphoid-trapezoid arthrosis was observed following trapeziectomy. No other preoperative radiographic factors investigated were associated with significant differences in preoperative and postoperative values for radiographic outcome measures. Conclusions: Trapeziectomy can lead to loss of carpal height, coordinated extension of both the lunate and scaphoid, and progressive scaphotrapezoid arthrosis. As such, in wrists with dynamic or static carpal instability, trapeziectomy should be performed with caution due to the risk of carpal collapse with a nondissociative pattern of dorsal intercalated segment instability.