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

Abstract: Tissue expansion has become one of the routine methods in breast reconstruction. 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 reconstruction with tissue expansion. Mastectomized women who had their breasts reconstructed by means of tissue 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 was a low rate of complications and patients were satisfied in 82% of the cases. Capsular contraction incidence was 28%. The disadvantage of the method is the long time necessary for reconstruction. Mitotic activity of the basal cell layer of the epidermis, where new cells are produced, was studied with autoradiography. There was a significant rise in labeled cells induced by expansion, implicating formation of new cells. This was accentuated by the fact that insulin-like growth factors I and II, studied by immunohistochemical technique, showed increased levels after expansion in the basal layer of the epidermal keratinocytes. The thickness of the epidermis was studied before, during and six months after expansion. Epidermal thickness showed maximal values during expansion and values before and after did not differ significantly from each other. The total skin thickness and biomechanical properties (elasticity, hysteresis and distensibility) were investigated in patients who were slowly and rapidly expanded. Measurements of skin thickness were performed with ultrasound technique at five occasions before, during and after expansion. Skin thickness was decreased during the expansion procedure with a minimum at maximal expansion. Two weeks after implantation there was an increase in thickness. Six months and 4 years after completed reconstruction, however, epidermis was thinner than before reconstruction. There was no difference between the groups 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, but no difference between groups was noted.