Use of the swanson silicone trapezium implant for treatment of primary osteoarthritis - Long-term results

Background: Instability of the prosthesis and silicone-induced synovitis ha ve led most surgeons to abandon use of the Swanson trapezium implant for th e treatment of primary osteoarthritis. However, the literature contains lit tle information on the results of long-term follow-up. The present study wa s conducted to establish the long-term results and to highlight the problem s associated with the implant. Methods: Thirty-five patients (forty-five implants) of our initial forty-fi ve patients (fifty-seven implants) were available for clinical review. The mean duration of follow-up was 13.8 years. The objective result was assesse d with a 40-point clinical scoring system. The subjective result was measur ed with a visual analog scale. A clinical score of 30 to 40 points and a su bjective score of 8, 9, or 10 points were considered a good-to-excellent re sult. Radiographs were evaluated to determine the position and deformation of the prosthesis and to check for osteolytic changes of the bone, indicati ng silicone-induced synovitis. Results: The overall clinical and subjective results were good for twenty-s even thumbs (60%). Eighteen thumbs (40%) had a dislocation, and nine of the m had a revision. Three more revisions were carried out because of silicone -induced synovitis, persistent pain after reflex sympathetic dystrophy, and deep infection in one thumb each. Revision surgery consisted of resection of the implant, with or without tendon interposition, or implantation of a new prosthesis. Of the thirty-two prostheses (thirty that had not been revi sed and two that had keen revised) for which follow-up radiographs were ava ilable, six (19%) showed wear and deformation and five (16%) also were asso ciated with osteolytic changes. Conclusions: The main problem associated with the prosthesis was dislocatio n. Surgical measures to improve stability did not prevent this complication . The results after revision because of dislocation were no better than tho se associated with unrevised dislocated implants. In addition to dislocatio n, radiographic signs of silicone-induced synovitis were frequently noted, although they did not necessarily lead to a poor result. We concluded that the results after long-term follow-up of the Swanson silicone trapezium imp lant for the treatment of primary osteoarthritis were poor and that our dec ision to stop using this implant in 1991 was correct.