A New Approach for the Correction of Type I Thumb Deformity Owing to Rheumatoid Arthritis

Abstract

A major transition in the surgical treatment of rheumatoid arthritis has been facilitated by a recent paradigm shift in its diagnosis and treatment. Improved outcomes in the treatment of the rheumatoid thumb are desirable; however, the results of conventional surgery are less than ideal. Even if the rheumatoid arthritis is well-controlled, the progression of thumb deformity may persist owing to an ineffective deformity correction and an insufficient understanding of the mechanism by which the deformity occurs. The mechanism of rheumatoid thumb deformity should be considered, using it to base the appropriate correction. We applied a new deformity correction procedure that accounts for the mechanism of type I rheumatoid thumb deformity and obtained positive results without recurrence. Although the primary cause of type I thumb deformity is believed to be an extensor mechanism failure resulting from synovitis of the metacarpophalangeal (MCP) joint, surgical outcomes are negatively affected as a result of flexion contracture caused by the adductor pollicis (ADP). Because the ADP attaches to the ulnar sesamoid on the palmar side of MCP joint, we release the ADP tendon to improve flexion contracture of the MCP joint. We consider release of ADP to be effective in preventing the recurrence of flexion contracture of the MCP joint and re-tensioning of the extensor pollicis brevis. Rheumatoid thumb deformity can be restored by applying this procedure, improving a patient’s outcome. Key words: correction, flexion contracture release, Nalebuff type I deformity, rheumatoid arthritis, thumb