The fibrous capsules around static and dynamic implants: their biochemical, histological, and ultrastructural characteristics.

In this article, we report the findings of a small study comparing the histological, ultrastructural, and biochemical features of fibrous capsules formed around tissue-expanding devices (dynamic implants) and simple prostheses (static implants) in the human. Histologically and biochemically, the dynamic fibrous capsule appears to represent an early phase of scar tissue formation around an expanding foreign body, the dominant feature being increased cellularity caused by myofibroblasts. In view of the marked presence of these contractile elements, it is paradoxical that a lower capsular contracture rate should be reported to occur in breast reconstruction using a temporary expander. This lower rate presumably is because these myofibroblasts undergo modulation once the expansion process has ceased and the final prosthesis is in place. One may also assume that the fibrous capsule would retain features of early scar tissue if the expansion process is maintained indefinitely. This hypothesis can be evaluated by a long-term study in the animal.