Evaluation of the first metacarpal proximal facet inclination as a prognostic predictor following arthroplasty for osteoarthritis of the thumb carpometacarpal joint.

We have retrospectively reviewed 17 thumbs in 16 patients with osteoarthritis of the thumb carpometacarpal joints, for which arthroplasty was performed using Kaarela's method. Postoperatively, three thumbs in two patients had poor outcomes; both patients had a sharp slope of the base of the first metacarpal. Serial radiographic measurements suggested that this sharp slope affected the adducted position of the first metacarpal, and led to the appearance of a metacarpophalangeal joint hyperextension deformity of the thumb. This radiological finding could be a prognostic predictor after surgery for osteoarthritis of the thumb carpometacarpal joint.