A new flap model in rats: Iliac osteomusculocutaneous flap

Although osteomusculocutaneous flaps are used frequently in clinical practi ce to repair defects involving soft tissue and bone, there are still many q uestions that remain to be answered regarding their basic physiology. To ac complish such basic science studies, simple and reliable animal osteomuscul ocutaneous flap models are needed. The purpose of this study was to describ e a new flap model in rats-namely, the iliac osteomusculocutaneous flap. Th irty 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 relati on 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 abdomi nal wall muscle cuff. In 10 rats, the flap was raised as an island flap bas ed 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 ski n island of all the flaps was completely viable. Bone scintigraphy performe d on postoperative day 3 in free flaps demonstrated radionuclide uptake, in dicating viability of the bony segment. The dye injection study revealed in k staining within blood vessels of the bone, confirming its viability. Micr oangiography of the flap demonstrated vascularity of each component of the flap by the iliolumbar vessels, including a distinct branch to the iliac bo ne. The authors conclude that the iliac osteomusculocutaneous flap of the r at 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 co nsistent, and (4) it is harvested from a small-animal species.