The fate of intramuscularly injected fat autografts: an experimental study in rabbits.

An experimental study was designed to assess the viability and revascularization of intramuscularly injected fat autografts. For the study, 18 rabbits were divided into two groups. In the first group, fat was injected intramuscularly (12 rabbits). Autologous fat was obtained from the inguinal area and subsequently injected into the thigh muscle. In the second group, physiologic saline was injected intramuscularly to determine the effects of cannulation and pressure on muscle tissue (6 rabbits). Fat autografts were performed on the right side of the animal, and the left side was used as the control. Scintigraphic imaging and histopathologic examination of the limbs were performed after injection of adipose tissue on days 15, 30, 45, 60, 90, and 120. On the technetium-99m ((99m)Tc) hexamethylpropylene amine oxime scintigraphy, whereas similar activity distribution was observed between the left and right thigh on days 15, 30, and 45, there was increased uptake at the right thigh on days 60, 90, and 120. This increased uptake indicates that there is viable fat tissue in this region. Histopathologic evaluation showed that microcysts resulting from degeneration of some adipocytes and inflammatory changes on day 15 additionally increased vascularity and fibrosis in some animals on day 30, as well as fibrosis, microcysties, and focal calcification areas in adipose tissue on day 45 and later. It was observed that adipose tissue survived in more than 50% of the graft area in all the animals. These findings show that fat autografts can survive in muscle tissue with less than 50% fibrotic change.