Rate of diffusion of Solu-Medrol across the silastic membranes of breast prostheses-an in vitro study.

Many plastic surgeons have used steroids in breast prostheses in augmentation and postmastectomy reconstruction to prevent capsular contracture. The detection and incidence of complications have increased during the last several years. It is probable that the incidence of complications is related to two factors. First, clinicians have used the same doses in the smaller outer compartments of bilumen implants, giving a much higher concentration of steroid. Second, the more recent implants have thinner envelopes. Tritiated Solu-Medrol was placed in the outer lumen of the bilumen Heyer-Schulte, McGhan, and Surgitek prostheses, and in the only lumen of inflatable Mammatech and Heyer-Schulte prostheses. Diffusion of the Solu-Medrol from each of these identically sized prostheses into the surrounding saline bath was measured with a liquid scintillation counter. Diffusion rates provided concentration-dependent, as predicted by Donnan-Gibbs equilibrium. The silicon gel in bilumen implants was found to represent a second Donnan-Gibbs equilibrium and result in a lower diffusion rate because of affinity for the steroid.