Silastic implant arthroplasty of the second to fifth metacarpophalangeal joints in rheumatoid arthritis

PURPOSE OF THE STUDY The authors evaluate the long-term results of metacarpophalangeal joint (MCP) arthroplasty of the second to fifth digits in the rheumatoid hand in relation to the factors that have a long-term effect on implant function. MATERIAL In a group of 41 patients, 52 hands were treated with a total of 166 Swanson silastic MCP implants in the period from 1988 to 2005. The average follow-up was 3.2 years (range, 6 months to 17 years). Arthroplasty was carried out exclusively for the indication of rheumatoid destruction of MCP joints. METHODS The patients were assessed for the range of motion, MCP joint alignment and functional and radiographic findings. Xray images were examined for osseous lesions at the margins of resected parts, implant position and its state and joint alignment. Radiography was performed from the standard distance in anteroposterior and oblique projections. Subjective satisfaction of the patients was evaluated on the basis of a questionnaire, in which hand function, pain and cosmetic appearance were recorded. RESULTS The function and mobility of the fingers improved after surgery, with an increased range of motion in MCP joints towards extension (average range, 3 degrees to 51 degrees flexion), and correction of an ulnar drift of the MCP joint of each finger (average, 5.8 degrees). Radiographs showed destruction of silastic implants in 13.3 % of the fingers treated. The subjective evaluation by patients was satisfactory. Long-lasting pain relief was reported by 79 % and satisfaction with hand function by 90 % of the patients. Improvement in a cosmetic appearance of the hand was also significant. DISCUSSION At long-term follow-up, a gradual decrease in the range of motion of MCP joints and a partial recurrence of ulnar drift usually occur at about 2 years. However, in most cases, they do not result in either subjective complaints or functional restriction. These findings are in agreement with the results published in the relevant literature. CONCLUSIONS The silastic implant remains a standard procedure in surgical reconstruction of the MCP joints in the rheumatoid hand. Improvements in the range of motion and joint alignment and alleviation of pain result in a markedly improved hand function and patients' satisfaction. The long-term outcome of MCP joint arthroplasty is significantly influenced by the severity of rheumatoid arthritis.