Silicone implants.

Infection has not been considered in this article with each individual implant. The incidence is low indeed. In the only publication concerned primarily with the topic of infection following silicone implant surgery, Millender et al. reviewed 2105 implants of varying kinds. There were ten infections, seven of which were with Staphylococcus aureus. The onset was remarkably late--17 days after surgery on average. In seven cases the implant had to be removed and the eventual result was good, being likened to that obtained after an excisional arthroplasty. Reviewing the complications that occur with the various implants, it becomes evident that there are three primary concerns--fracture, subluxation, and synovitis. Fracture occurs primarily in the wrist and the metacarpophalangeal implants. The incidence of fracture in the wrist implant is 8.6, 9.4, and 19.8 per cent, giving an average of the means of 12.6 per cent. In the metacarpophalangeal joint, the incidence with the Swanson design is variously 1.9, 26.2 and 21 per cent, the average of the means being 16.4 per cent. The Niebauer design is reported as having a fracture rate of 29.7 and 38 per cent, for an average of the means of 33.9 per cent. The somewhat lower incidence of fracture of the wrist implant is offset by the fact that, in contrast to the situation with the smaller joint, the fracture is almost always symptomatic, requiring treatment. Largely for this reason, silicone wrist arthroplasty is limited mainly to the rheumatoid patient, being little used for post-traumatic arthritis. Subluxation of implants occurs mainly with the carpal replacements. The incidence in independent reports are 56.5 and 50 per cent, for an average of the means of 53.3 per cent with the scaphoid; 20, 20, and 50 per cent for an average of the means of 30 per cent with the lunate; and 5.3, 10, 11.2, 29, and 32 per cent for an average of the means of 17.5 per cent with the trapezium. In the case of the trapezium, excision of a portion of the trapezoid, supplemented where necessary by ligament reconstruction to support the first metacarpal, appears to give the hope of lowering the incidence of subluxation to an acceptable level. With the lunate, preservation of an anterior shell may give satisfactory results but judgment should await longer term studies of larger groups. The scaphoid implant gives most cause for concern, both because the incidence is high and because the solutions offered have either failed or are too recent to judge and perhaps too radical to accept.(ABSTRACT TRUNCATED AT 400 WORDS)