A new flap model in rats: iliac osteomusculocutaneous flap

Although osteomusculocutaneous flaps are used frequently in clinical practice to repair defects involving soft tissue and bone, there are still many questions that remain to be answered regarding their basic physiology. To accomplish such basic science studies, simple and reliable animal osteomusculocutaneous flap models are needed. The purpose of this study was to describe a new flap model in rats--namely, the iliac osteomusculocutaneous flap. Thirty adult Wistar rats weighing 200 to 250 g were used in this experiment. In 15 rats, the vascular anatomy of the iliolumbar vessels and their relation with adjacent soft tissues and the iliac bone was determined by anatomic dissection. Based on this anatomic study, the iliac osteomusculocutaneous flap model was created in rats. The flap is comprised of a skin island (3 x 3 cm) in the flank region, a 1 x 1-cm segment of iliac bone, and an abdominal wall muscle cuff. In 10 rats, the flap was raised as an island flap based on its vascular pedicle of iliolumbar vessels, and was replaced in situ. In the remaining 5 rats, the flap was transferred to the groin region as a free flap. Direct observation on postoperative day 7 revealed that the skin island of all the flaps was completely viable. Bone scintigraphy performed on postoperative day 3 in free flaps demonstrated radionuclide uptake, indicating viability of the bony segment. The dye injection study revealed ink staining within blood vessels of the bone, confirming its viability. Microangiography of the flap demonstrated vascularity of each component of the flap by the iliolumbar vessels, including a distinct branch to the iliac bone. The authors conclude that the iliac osteomusculocutaneous flap of the rat is a simple and reliable flap model that offers the following advantages: (1) It is a true osteomusculocutaneous flap, (2) it can be used as a free flap without the need for an isogeneic rat, (3) the vascular pedicle is consistent, and (4) it is harvested from a small-animal species.