[Unusual complication of silicon synovitis in the rheumatoid wrist]

Silicone synovitis is an important clinical entity recognized in rheumatoid patients after arthroplasties with silicone implants. It is a foreign body reaction to particulate material (silicone elastomer) characterized clinically by the re-occurrence of pain, stiffness and swelling at the site of arthroplasty after initial relief of symptoms. Whereas silicone synovitis is a rare complication in metacarpophalangeal implants, it is an important one in the wrist implant. Long-term follow-up studies have revealed that the rates of fracture and subsidence are high and that the implants deteriorate with time necessitating operative revisions in up to 50% of cases. Indications should therefore be restricted to a painful wrist in the elderly, very low demand patient with insufficient bone stock to permit total wrist arthroplasty with a metal-on-plastic design. Severe preoperative deformity and the need for use of ambulatory aids may further limit the indication. The unusual case of direct perforation of silicone particles from the wrist into the tendon sheath of the M. flexor pollicis longus inducing a tumor-like synovitis and a secondary carpal tunnel syndrome is presented. The importance of silicone synovitis and the indication at present for implantation of a silicone wrist spacer in the rheumatoid patient are discussed.