Pantrapezial osteoarthritis (OA), combining trapeziometacarpal (TMC) and scaphotrapeziotrapezoid (STT) joint involvement, has long been considered a relative contraindication to TMC arthroplasty. The aim of this study was to evaluate the functional and radiological outcomes of TMC prostheses in patients with or without associated STT OA.

This retrospective, observational, non-randomized, multicentre study included patients treated with a single mobility TMC prosthesis (ISIS® or HORUS®) between November 2007 and December 2023 in two centres. At final follow-up, patients were assessed using validated self-reported questionnaires (QuickDASH, Buffalo score, TASD), a self-administered Kapandji score, and an indirect estimation of pinch strength (A4 paper-folding test). Preoperative and final follow-up radiographs were analyzed using the Dell, Crosby, and SCFM classifications described by Obert et al.

One hundred and thirteen prostheses in 94 patients were analyzed, with a mean follow-up of 6.4 years. Forty prostheses were implanted in a context of pantrapezial OA. No statistically significant differences were observed between groups (isolated rhizarthrosis vs pantrapezial OA) regarding functional scores or radiological complications. Radiological progression of STT OA was observed in 20% of cases, without significant functional impact.

The presence of associated STT OA did not appear to impair clinical outcomes after TMC arthroplasty at mid- and long-term follow-up. Surgical decision-making should primarily rely on patient symptoms and expectations rather than radiographic findings alone.