Background: Instability of the prosthesis and
silicone-induced synovitis have led most surgeons to abandon use
of the Swanson trapezium implant for the treatment of primary osteoarthritis.
However, the literature contains little information on the results
of long-term follow-up. The present study was conducted to establish
the long-term results and to highlight the problems associated with
Methods: Thirty-five patients (forty-five implants)
of our initial forty-five patients (fifty-seven implants) were available
for clinical review. The mean duration of follow-up was 13.8 years.
The objective result was assessed with a 40-point clinical scoring
system. The subjective result was measured with a visual analog
scale. A clinical score of 30 to 40 points and a subjective score
of 8, 9, or 10 points were considered a good-to-excellent result.
Radiographs were evaluated to determine the position and deformation
of the prosthesis and to check for osteolytic changes of the bone,
indicating silicone-induced synovitis.
Results: The overall clinical and subjective results
were good for twenty-seven thumbs (60%). Eighteen thumbs
(40%) had a dislocation, and nine of them 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 revised and two that had been revised) for which follow-up
radiographs were available, six (19%) showed wear and deformation
and five (16%) also were associated with osteolytic changes.
Conclusions: The main problem associated with the
prosthesis was dislocation. Surgical measures to improve stability
did not prevent this complication. The results after revision because
of dislocation were no better than those associated with unrevised
dislocated implants. In addition to dislocation, 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
implant for the treatment of primary osteoarthritis were poor and
that our decision to stop using this implant in 1991 was correct.