Experimental Comparison of Survival between Dermis-Fat Graft and Fascia-at Graft

ABSTRACT

The use of autologous fat grafts for soft-tissue augmentation has an extensive history, but it's not popular because of the questionable clinical value due to unreliable grafts survival or infection. To compensate for the volume reduction, transplanted fat is placed intramuscularly and fat graft have been performed, considering basic fibroblast growth factor or endothelial cell growth factor. As is generally known, Watson(1959) stated that the dermal portion exerted a stronger vasoinductive effect than fat alone, thereby increasing the chance of fat survival. However, dermis-fat was harvested from concealed area, the procedure resulted in skin disfigurement. Our hypothesis is that the dermis or fascia, when included in a fat graft, not only makes technical handling and placement easier, but also presumably establishes an early vascular anastomosis with the recipient area, thereby decreases the total amount of resorption of the fat. This study is designed to assess the survival of dermis-fat graft and fascia-fat graft. Sixteen New Zealand White rabbits weighing about 2 kilograms and ranging from 5 to 7 months of age were used. Dermis-fat tissue was removed from the left groin fat pad and fascia-fat tissue from the right groin fat pad. Each graft volume was more than 1.5 cc. To create the ear pockets, a 1 x 1 cm piece of cartilage with its perichondrium was removed. Dermis-fat was implanted below the dermis of the left dorsal ear and fascia-fat below the dermis of the right dorsal ear. Biopsy specimens from each implanted area were taken after 1, 4, 12 and 24 weeks(4 animals at each period). The graft was measured by immersing them in a mass cylinder of normal saline and recording the fluid displaced. Soon after removal, their volume was measured as before. In the first week grafted tissue of dermis-fat and fascia-fat was surrounded by a collagen capsule. In time, specimens showed partial firmness to palpation vn both sides. No obvious gross distinction between the two groups was observed. In specimens taken 1 and 4 weeks after transplantation of dermis-fat and fascia-fat, adipocytes were visible between macrophages and inflammatory cells. At longer intervals, 12 to 24 weeks, the transplanted dermis-fat and fascia-fat were successively replaced by connective tissue; however, inflammatory cell and cystic cavity were still visible. Analysis of volume maintenance(74 versus 71 percent) revealed no significant difference(p<0.05, Wilcoxon signed ranks test) after comparing the volume of dermis-fat versus fascia-fat. Our experimental study proved that volume maintenance and histologic findings between dermis-fat grafts and fascia-fat grafts are similar. Therefore, fascia-fat grafts can be used and offers better aesthetic improvement than dermis-fat grafts without tension on primary closure and hyperpigmentation of donor site.