A 33-year-old male suffered a severe Gustilo-type IIIB open fracture of the lower right leg after being run over by a car. As extensive soft-tissue loss was observed over a wide and complex area, reconstructive surgery was performed using latissimus dorsi musculocutaneous and serratus anterior flaps approximately two weeks after the incident. While the posterior tibial arteries and veins were selected as recipient vessels, revascularization could not be achieved, which resulted in avascular necrosis of the flaps. Thus, salvage surgery involving free flap reconstruction was conducted using the femoral arteries and veins as recipient vessels. This time, the procedure was successful. Tibial union was achieved within one year of the surgery, and the patient recovered to a point where he could engage in weight-bearing walking outdoors. Free omental flaps are an effective option for the reconstruction of injured extremities, where extensive soft-tissue loss is observed over a wide and complex area, no appropriate local recipient vessels are available, and there is an urgent risk of deep infection.