The dependence of free flaps on the original vascular anastomosis was investigated using color duplex . Although functional and morphological changes in flaps have been previously documented, showing the formation of new vessels across the flap inset, this was not observed in this study. Even after 1 year after surgery the free flaps were still dependent on the original anastomoses for their blood supply, with no other significant vessels obvious on duplex to supply the flap. This evidence as well other published reports suggest that at least the lower extremity and the chest wall do not develop collateral circulation to a free tissue transfer. Late postoperative division of the vascular pedicle either in the lower limb or the chest wall should be approached with the knowledge that neovascularization across the flap margins is the exception rather than the rule.
