Experimental Investigation into the Effect of Variable Inflation Intervals on Capsule Thickness in Tissue Expander

Introduction: Increasing the thickness of the capsule around the tissue expander, as in breast reconstruction complicates the expansion process and increases the time to achieve the required flap size. The aim of this study was to investigate the effect of changes in inflation intervals and amounts on the capsule thickness around the tissue expander. Methods: Fifteen adult rats were divided into 3 groups, and 25 cc elliptical tissue expanders were placed on the back of each, and inflated with 5 cc saline. Expanders were inflated daily in Group 1, every 3 days in Group 2, and every 10 days in Group 3. Inflation was stopped, then expanders were removed and skin flaps were harvested after the results of the expansion were measured. Biopsies containing skin and capsule tissue were evaluated by histomorphometry and immunohistochemistry. Results: Skin flaps were measured as 81 cm² in Group 1 and 89.3 cm² in both Groups 2 and 3. When capsule thickness and number of vessels were examined; the thickest capsule was found in Group 2 while Group 3 had the densest vascularization. On histopathological examination of the biopsies, no significant difference was found between groups, except for the histiocyte density, which was the lowest in Group 1 and the highest in Group 3. Conclusions: This experiment showed that inflating tissue expander in small amounts at frequent intervals decreased the thickness of the capsule but it resulted in smaller skin flaps. Thus, it may be beneficial to adopt this protocol in some patients, for example in patients who are predicted to have increased capsule thickness due to the effect of radiotherapy and/or chemotherapy, or who are prone to fibrosis. Additionally, in patients whose flap size is important, it may be reasonable to inflate the tissue expander at less frequent intervals and in relatively large volumes for preventing flap loss and avoiding an increase in capsule thickness.