Outcomes of the Dual Mobility Trapeziometacarpal Prosthesis versus Retentive Cup Prosthesis: Review of 118 Cases.

Since its invention, the ball-and-socket prosthesis has played a significant role in treating carpometacarpal osteoarthritis of the thumb. One of the main postoperative complications remains prosthetic dislocation. To reduce this risk, engineers developed new designs - primarily the retentive cup and the dual-mobility cup. The aim of this study was to compare the stability and outcomes of these two designs, focusing specifically on dislocation as the primary variable. All Maia prostheses (n=118) implanted between 2019 and 2023 at a single institution by two surgeons using the same surgical technique were retrospectively reviewed. The type of implant, dislocation and complication rates, functional outcomes, and patient satisfaction were analyzed. Although the overall complication rates did not differ significantly between groups, the retentive cup group had a slightly higher rate of dislocation (n=2; 3%) compared to the dual-mobility group (n=0; 0%) (p = 0.55). Satisfaction rates, functional scores, QuickDASH results, and range of motion were similar between the two groups and comparable to those of the general age-matched population at midterm follow-up. This study found a low postoperative dislocation rate in both groups, with no dislocations in the dual-mobility group. Although the difference was not statistically significant, the dual-mobility design may demonstrate superior stability in larger cohorts. Both implant types showed reliable performance and high survival rates at midterm follow-up.