PURPOSE: Silicone replacement arthroplasty has proven to be an effective procedure for relief of pain and improvement in range of motion in select patients with Rheumatoid Arthritis (RA). We know of no large published series that has examined the results of isolated metacarpophlangeal (MCP) Arthroplasty for osteoarthritis. The purpose of this study was to review the senior author’s technique and results of silicone replacement arthroplasty for isolated MCP post-traumatic and primary osteoarthritis (OA) and to identify factors associated with a poor outcome.

METHODS: Twenty-four patients with isolated MCP posttraumatic OA and primary OA underwent silicone replacement arthroplasty. Average age at operation was 49 years (range 24-74 years). 16 cases involved middle, 4 index, 2 ring and 2 small MCP joints. Two patients had a history of Diabetes Mellitus. All patients were evaluated preoperatively in the office. 9 patients had primary OA with the remainder having arthritis associated with a history of trauma. The primary indications for operation were pain unresponsive to conservative treatment, loss of range of motion and X-ray findings consistent with degenerative arthritis. Length of follow up averaged 43 months.

TECHNIQUE: The operative technique for isolated MCP arthroplasty, as opposed to multiple arthroplasties, involved an axial rather than transverse skin incision. In contrast to the technique we use for rhuematoid patients, we resected the metacarpal head just distal to the origin of the collateral ligaments rather than proximal. This allows more stability, preserves length and leads to more physiologic motion.

RESULTS: Good pain relief at the MCP joint was obtained in 21 of 24 patients. The average postoperative range of motion was 68 degrees. Major complications included infection in two patients requiring removal of the prosthesis. Patients with primary OA had the best results with some patients obtaining an 85 degree arc of motion. The postoperative range of motion was proportional to the preoperative range of motion in the postraumatic cases.

CONCLUSION: Patients with the best overall results were those with primary isolated MCP OA. Patients with posttraumatic OA, major concomitant soft tissue injuries and stiffness involving other digits had the poorest results.