The effect of nonpreserved human amniotic membrane on the survival of ischaemic skin flaps in rats

Abstract

Random-pattern skin flaps are used widely in plastic surgery, but necrosis resulting from ischaemia in the distal sections of the flap is a serious problem. Free oxygen radicals and the accumulation of increased neutrophil granulocytes play important roles in tissue injury and may lead to partial or complete necrosis of the flap. Amniotic membrane is a biomaterial used widely in clinical settings to prevent the infiltration and activation of leucocytes. The aim of this study was to test the effects of amniotic membrane on the survival of ischaemic skin flaps in rats. A total of 32 male rats were divided randomly into four groups of eight, according to the procedure to be tested: flap-only (F), flap-amniotic membrane (FA), flap-Tegaderm(®) (FT) and flap-amniotic membrane-Tegaderm(®) (FAT). Rectangular, random-pattern, caudally based modified McFarlane skin flaps were elevated at the dorsum of the rats in all four groups. The flap-only group was also the control group; in this group, the flaps were elevated and sutured to their native position. In the FA group, after the flaps were elevated, the amniotic membrane was inserted underneath the undersurface of the flap. In the FT group, after the flaps were elevated, a piece of Tegaderm was inserted underneath the undersurface of the flap. In the FAT group, the amniotic membrane was inserted underneath the undersurface of the flap and the Tegaderm(®) was inserted in the flap donor area. The survival rate of the skin flaps was measured on day 7, and histologic assessments were performed. The survival rate of the skin flaps was significantly improved in the FA and FAT groups (67-69%, p<0.05) compared with the F and FT groups (46-48%, p<0.05). Histologic analysis showed many more blood vessels and fewer neutrophils in the FA and FAT groups than in the F and FT groups. This study showed that amniotic membrane could improve the survival rate of ischaemic skin flaps.