The first carpometacarpal (trapeziometacarpal) joints are a frequent site of osteoarthritis in postmenopausal women. This osteoarthritis, which is typically bilateral both clinically and roentgenographically, may be mistaken for tenosynovitis unless its characteristic features are recognized. These features include tenderness, stiffness, crepitus, swelling, and pain on wringing movements or other motions that cause abduction of the thumb. The swelling, radial subluxation of the metacarpal and atrophy of the thenar muscles give the hand a squared appearance.In severe cases, conservative medical therapy is generally unsatisfactory. Intra-articular corticosteroids and local anesthetic give only transient relief. Results of surgical therapy, including excision of the trapezium or arthrodesis of the trapeziometacarpal joint, were in general good. Distinct indications exist for each type of operation.