The Effect of Hyaluronic Acid Application on the Perisilicon Capsule Structure

Silicon implants constitute a major part of plastic surgery practice. Although materials with high biocompatibility have been used around the implants, capsule formation still develops and progressive nature of this process results in capsule contraction. The aim of this study is to evaluate the effects of hyaluronic acid injected around the silicon block on the capsule structure. Twenty Wistar albino rats were used in the study. Rats were divided into two main groups (group 1 and group 2) and two subgroups. Rats in group 1 were sacrificed in week 4 and rats in group 2 were sacrificed in week 8. A subcutaneous pouch was created in the dorsum of the rats and a silicon block was placed into the pouch in groups 1A and 2A. 0.2 ml of hyaluronic acid was injected around the silicon block in group 1B and group 2B. Rats were sacrificed and capsule structure and thickness were analyzed following macroscopic evaluation. Concentrations of transforming growth factor-beta 1 (TGF-beta 1) and heat shock protein-47 (HSP-47) were evaluated immunohistochemically, and statistical comparisons were made. Capsule structure consisted of three layers in all the groups. A more intense collagen structure was observed in the middle layer. The capsule was thinnest in group 1A and thickest in group 2B; the difference between the groups was statistically significant. TGF-beta 1 was most intense in group 2B and it was correlated with the amount of collagen. Involvement of HSP-47 was observed mainly in collagen and also in fibroblasts and vascular structures, and its concentration was found to be lower in groups 2A and 2B. Exogenously added cross-linked hyaluronic acid increased the capsular thickness and may increase the risk of developing capsular contracture around silicone implants. Evidence was obtained from the well-designed controlled trials without randomization.