Trapeziometacarpal (TMC) arthroplasty is a widely accepted treatment for osteoarthritis of the TMC joint. However, one potential complication is De Quervain’s tenosynovitis and its cause post-arthroplasty remains unclear. The aim of this study was to evaluate whether thumb lengthening, as measured by the Scaphometacarpal Index (SMI), is associated with the incidence of De Quervain’s tenosynovitis following TMC arthroplasty.

A retrospective analysis was conducted of 114 TMC arthroplasties performed between 2015 and 2022. Thumb lengthening was quantified using pre- and postoperative radiographs.

The incidence of De Quervain’s tenosynovitis was 4.4%. Statistical analysis showed no significant association between thumb lengthening and the incidence of tenosynovitis (p = 0.75). Additionally, no correlation was found between thumb lengthening and postoperative pain (p = 0.89), range of motion (p = 0.90), and functional outcomes(p = 0.19).

These findings suggest that thumb lengthening after TMC arthroplasty does not significantly contribute to De Quervain's tenosynovitis, pain, range of motion and functional outcomes.

The main limitation of this study is the limited statistical power due to the low incidence of De Quervain’s tenosynovitis. Results should therefore be interpreted with caution.