Neovascularization of skin flaps: route and timing

Axial flaps were elevated in a pig and rat model. Selective ligation of the vascular pedicles on days 1 to 7 following elevation of the flap demonstrated total necrosis of all flaps when the pedicles were ligated on the first, second, and third postoperative day in the pig, and up to 6 days inthe rat. Pedicle ligation beyond this time did not produce flap necorsis, indicating the establishment of adequate neovascularization for flap survival. Selective ligation of the artery or vein did not appear to be significant in the pig. In the rat flap, however, survival tended to occur sooner. Adequate neovascularization for flap survival was demonstrated as arising from both the wound edges and the bed, although vascular channels occurring from the bed appeared to be of greater importance. The relatively rapid rate of neovascularization that occurs for adequate flap survival suggests that if some way could be found to maintain flap viability during the first week, the feeding vessels need no longer remain patent and may be ligated or used for other purposes. This interesting observation has already allowed very early successful defatting of clinically transferred flaps.