Even when we assess accurately the preoperative vascular damage of the blood vessel we intend to use for reconstruction, difficulties may arise during operation which cannot be resolved by routine methods. Microvascular surgery is an important part of many modern reconstruction procedures which can be used during reconstruction of the extremity. As an example the authors describe injuries of the left foot involving loos in a 41-year-old patient who was knocked down by a taxi. The defect denuded the bone and loss of soft tissues of the heel called for free transfer of a vascularized flap. During operation venous thrombosis and subsequently arterial thrombosis developed. The use of an interposed vein helped to ensure a sufficient blood supply to the transferred tissue. The left foot healed well.