[Synovitis of the wrist joint following silicone replacement of the carpal bones]

The authors report on six patients in whom an aggressive synovitis of the wrist and erosion of the adjacent bones has developed after insertion of Silastic implants in the region of the carpus. Systemic disease, dislocation or fracture of the prosthesis was not present. In surgical revision, the prosthesis shows changes in form and rough surfaces. The synovial membrane is massively thickened and highly inflamed with pannus formation; the adjacent bone showed cartilage loss and fragmentations. Light and electron microscopic investigations of the synovial membrane and the bone show giant cells with silicone particles. We consider that compression, shearing forces as well as abnormal movements are to be considered primarily as causes of attrition. Other factors such as age, profession and location hardly play any role. Prostheses which are too large, the presence of osteophytes and structural loosening of the carpal bones are avoidable risks. After removal of the prosthesis and the synovial membrane, there is rapid healing. Subsequent arthrodesis also heals without problems.