The expanded skin in breast reconstruction : An experimental and clinical study

Sammanfattning: The expanded skin in breast reconstruction An experimental and clinical study MICHAEL OLENIUS Department of Plastic and Reconstructive Surgery and Department of Neuroscience Karolinska Hospital and Karolinska Institute, Stockholm, SwedenTissue expansion has become one of the routine methods in breast recon- struction. It is a safe and easy method, which is well accepted by the patient. Clinical reports are numerous, but morphological changes are still not thoroughly investigated. The main question in tissue expansion is, whether the gain of skin is the result of formation of new skin or from stretching of adjacent tissues. The changes in thickness of the epidermis and the dermis have been evaluated by several authors. However, the majority of reports on morphological and biomechanical alterations are based on animal models. All investigations in the present thesis were performed in humans, subjected to breast recon- struction with tissue expansion. Mastectomized women who had their breasts reconstructed by means oftissue expansion, were included in a prospective and consecutive study.Breasts were overexpanded to double the volume of the final prosthesis.Clinical evaluation was performed by two independent examiners. There wasa low rate of complications and patients were satisfied in 82% of the cases.Capsular contraction incidence was 28%. The disadvantage of the method isthe long time necessary for reconstruction. Mitotic activity of the basal cell layer of the epidermis, where new cells areproduced, was studied with autoradiography. There was a significant rise inlabeled cells induced by expansion, implicating formation of new cells. Thiswas accentuated by the fact that insulin-like growth factors I and II, studied byimmunohistochemical technique, showed increased levels after expansion inthe basal layer of the epidermal keratinocytes. The thickness of the epidermis was studied before, during and six monthsafter expansion. Epidermal thickness showed maximal values during expan-sion and values before and after did not differ significantly from each other. The total skin thickness and biomechanical properties (elasticity, hysteresisand distensibility) were investigated in patients who were slowly and rapidlyexpanded. Measurements of skin thickness were performed with ultrasoundtechnique at five occasions before, during and after expansion. Skin thicknesswas decreased during the expansion procedure with a minimum at maximalexpansion. Two weeks after implantation there was an increase in thickness.Six months and 4 years after completed reconstruction, however, epidermiswas thinner than before reconstruction. There was no difference between thegroups of rapidly and slowly expanded breasts. Biomechanical properties were studied with a suction chamber device.The different properties were altered during expansion to a minor extent, butno difference between groups was noted.Key words Tissue expansion, capsular contraction, rapid and slow expansion, mitotic activity,epidermal thickness, skin thickness, collagen diameter, skin properties, insulin-like growth factorStockholm 1995 ISBN 91-628-1823-6