• ABSTRACT
    • We hypothesized that metacarpophalangeal (MCP) joint hyperextension can be significantly reduced in patients with trapeziometacarpal joint (TMJ) osteoarthritis through TMJ dual mobility implant arthroplasty. Using registry data and propensity score matching, we compared 37 patients with preoperative MCP joint hyperextension >20° with 111 control patients with ≤20° extension. Before surgery, mean MCP joint extension was 34° (95% confidence interval 31-37) in the hyperextension group and 10° (95% CI 8-11) in the control group. Hyperextension was significantly reduced to 9° (95% CI 6-13) 6 weeks after surgery and was not significantly higher than the measured 5° (95% CI 4-7) in the control group. It remained stable for up to 2 years. Secondary outcomes including key pinch strength, pain, the brief Michigan Hand Outcomes Questionnaire and complications did not differ between groups at 2 years. Trapeziometacarpal joint implant arthroplasty can correct preoperative MCP joint hyperextension without additional procedures at the MCP joint.Level of evidence: III.