Answer:
Multiple causes of clinically evident capsular contracture have been identified including migration of silicone gel molecules across the elastomeric outer envelope, foreign body reaction, autoimmune (connective tissue disorders), a genetic predisposition to form encapsulation, infection or contamination by bacteria, hematoma, and the surface characteristics of the prosthesis. At the cellular level, abnormal fibroblast activity stimulated by a foreign body and a ubiquitous presence of Staphylococcus epidermidis bacteria remain popular explanations of fibrous contracture. Unfortunately, no specific etiology has been definitively identified. Earlier reports of improved softness and a decreased rate of encapsulation with polyurethane-coated devices have not been substantiated by longer-term follow-up, most likely because the polyurethane degrades and disappears. There is general agreement, however, that the incidence of severe capsular contracture is reduced substantially by subpectoral placement of the prosthesis and the use of saline devices. Antibiotic therapy in the form of systemic administration and local irrigation is emphasized as the mainstay of encapsulation prevention or reduction.