Interposition Arthroplasty with a Bioabsorbable RegJoint™ Implant Versus Total Joint Replacement with a Touch® Cementless Dual-Mobility Prosthesis in Advanced Trapeziometacarpal Osteoarthritis: A Prospective Comparative Cohort Study with Propensity S

Abstract Background: Osteoarthritis of the thumb carpometacarpal joint (CMC1) is a common cause of pain and impaired hand function, and no surgical technique has proven superior in advanced disease. We compared the early clinical and functional outcomes of interposition arthroplasty with a bioabsorbable RegJoint™ implant and total joint replacement with a Touch® cementless dual-mobility prosthesis. Methods: In a prospective single-centre comparative cohort study, 100 patients with Eaton–Glickel stage III–IV CMC1 osteoarthritis were allocated by block randomisation between January 2023 and November 2025; 95 completed the 6-month follow-up. Because the preoperative QuickDASH score differed between the groups (p = 0.0001), 1:1 propensity score matching was applied, yielding 26 matched pairs. Pain intensity (NRS), range of motion, grip strength and QuickDASH were assessed before surgery and 4 weeks, 8 weeks and 6 months afterwards. Results: Both groups improved significantly. At 6 months the Touch® group had lower pain intensity (median 0.0 vs. 1.0), greater grip strength (32.0 vs. 19.5 kg), better QuickDASH scores (26.7 vs. 48.4) and a wider range of motion in every plane (all p < 0.0001). Grip strength and function already differed at 4 weeks. Complications occurred in 1 of 26 and 2 of 26 patients, respectively. Conclusions: Total joint replacement provided faster and greater early functional recovery. The non-randomised analysis, the small matched sample and the 6-month follow-up mean that confirmation in registered trials with longer observation is required.