Insufficient flexion of the metacarpophalangeal joint of the little finger following Swanson silicone arthroplasty for rheumatoid arthritis.

Twenty-one patients with rheumatoid arthritis who underwent Swanson metacarpophalangeal (MP) arthroplasty from 1994 to 1999 were assessed for active flexion of individual MP joints an average of 59 months (range 27-114 months) postoperative. Published articles of Swanson MP arthroplasty were reviewed. Experienced hand surgeons were surveyed regarding outcomes of metacarpophalangeal arthroplasty. The MP joint of the little finger displayed significantly less flexion than that of the middle and index finger. Seven of eight published studies which present active MP flexion by individual digit demonstrated less flexion in the little finger compared to the index, middle, and ring finger. Half of surgeons surveyed reported that MP range of motion is shifted toward a more extended position, that MP flexion is limited in the ulnar digits, and that an implant that encourages MP flexion would be helpful. Our experience with this cohort, a review of published literature, and a survey of international experts suggest that Swanson arthroplasty frequently results in a range of flexion of the MP joint of the little finger that may be insufficient for its principal functions.