Flexible (silicone) implant arthroplasty of the metacarpophalangeal joint of the thumb.

Forty-four thumbs in thirty-four patients with rheumatoid arthritis were treated with a flexible implant arthroplasty of the metacarpophalangeal joint. After follow-ups ranging from two to six and a half years the results were rated good to excellent in forty-two thumbs since they were not painful, had an increased arc of motion of the metacarpophalangeal joint in a more functional range, and were more effective in the activities of daily living. The results in this series indicated that careful reconstruction of the extensor apparatus is essential, as well as stabilization of the interphalangeal joint either by arthrodesis or by tenodesis if there is a hyperextension deformity. Of the six patients who had a fusion of the metacarpophalangeal joint in one thumb and an arthroplasty in the other, five preferred the arthroplasty because the joint was stable and also had a useful arc of motion, while one noted no difference between the two thumbs.