The development, basic concepts, and technique of flexible implant arthroplasty of the metacarpophalangeal and proximal interphalangeal joints are described and the need for treatment of all the interrelated deformities in the fingers is considered.

The results after follow-ups ranging from six months to five years are analyzed both in the patients treated by me in Grand Rapids and in patients treated by the surgeons in 211 clinics who participated in a Field Clinic study. The Grand Rapids series included 358 metacarpophalangeal joints, all with rheumatoid arthritis, and 148 proximal interphalangeal joints, eighty-five with rheumatoid arthritis, thirty with osteoarthritis and thirty-three with post-traumatic arthritis. The over-all average range of motion achieved was from 2 to 64 degrees of flexion in the metacarpophalangeal joints and from 6 to 65.5 degrees of flexion in the proximal interphalangeal joints.

The Field Clinic Study series included 3,409 metacarpophalangeal joints, all in hands with rheumatoid arthritis. The average range of motion in the 2,544 fingers for which data were available in this series was from 4 to 57 degrees of flexion.

In both series, the deformity was corrected in 97 per cent or more of the fingers.

The complications in the combined series included fracture of the implant which occurred in less than 2 per cent of cases, and dislocation of the implant and infection both of which occurred in less than 1 per cent of the fingers. Five implants in the two series combined had to be removed because of postoperative infection.