Migration of silicone through the fibrous capsules of mammary prostheses.

The usual reaction of the human body to implantation of a silicone prosthesis is formation of a fibrous capsule. Local reactions to silicone outside this fibrous capsule and distant migration of silicone particles have been described. So far, transcapsular migration of silicone particles from the mammary implant through the fibrous capsule of mammary prostheses has not been studied. In this prospective study 71 capsules found in 40 patients were histologically studied. The chi-squared test was applied to evaluate a possible correlation between silicone migration on the one hand and implant age and integrity of the prostheses on the other. The degree of silicone migration was discerned in four stages. Stage 1 represents no silicone particles in the capsule, stage 2 represents migration up to less than half of the capsule thickness, stage 3 shows migration confined to the outer half of the capsule thickness, and stage 4 means transcapsular silicone migration. In only 4 of 71 capsules no migration into or through the capsule was observed. The degree of silicone migration was significantly less in patients in whom the capsule was calcified and was significantly more in patients in whom implantation exceeded 12 years. There was no significant correlation between the status of the prosthesis (intact, bleeding, or ruptured) and the degree of silicone migration.