Restoration of metacarpophalangeal extension of the thumb in inflammatory arthritis.

Nine patients (11 cases) with inflammatory arthritis who had an early boutonnière deformity of the thumb treated by rerouting of the extensor pollicis longus tendon were reviewed. Preoperatively, all patients complained of pain, disability in activities of daily living and extensor lag of the MP joint ranging from 10 to 60 degrees. At a mean follow-up of 38 months, nine thumbs had equal active and passive MP joint extension. Two thumbs had a moderate extensor lag. Functional strength assessment demonstrated no deleterious effect of the procedure in the operated compared to the non-operated thumb. Subjectively, all patients but one were satisfied. This procedure appeared to correct or to limit the progression of the deformity. A deficit of interphalangeal extension in five patients may require a modification of the procedure to tighten the extensor pollicis longus distal to the MP joint.