The long-term results of 144 arthroplasties of the metacarpophalangeal joints, with use of silicone-rubber implants, were reviewed for twenty-seven patients (thirty-six hands) who had rheumatoid arthritis. The operations were all performed or supervised by the same surgeon. All patients had an arthroplasty of the metacarpophalangeal joint of all four fingers, and all had subjective and objective clinical evaluation and roentgenographic assessment. Relief of pain, the cosmetic appearance of the hand, the range of motion of the metacarpophalangeal and proximal interphalangeal joints, and the presence of residual deformity were evaluated. The average duration of follow-up was eight years and six months (range, five years to sixteen years and three months). Preoperatively, the mean active-extension deficit of the metacarpophalangeal joints ranged from 53 degrees (index finger, right hand) to 70 degrees (little finger, left hand) and the mean flexion ranged from 84 degrees (index finger, right hand) to 94 degrees (little finger, left hand). At the early follow-up evaluation (average, four months postoperatively; range, two to six months), the mean extension deficit had improved to a range of 7 degrees (little finger, right hand) to 19 degrees (index finger, left hand), and mean flexion ranged from 56 degrees (little finger, left hand) to 66 degrees (ring fingers). The range of motion had improved from a non-functional arc of flexion to a more functional arc of extension. At the time of the latest follow-up visit, the motion of the metacarpophalangeal joints had not deteriorated.(ABSTRACT TRUNCATED AT 250 WORDS)