Novel Irradiated Axial Rotational Flap Model in the Rodent

IMPORTANCE Patients who require extensive surgical resection of head and neck tumors often have a history of treatment with radiation and chemotherapy. Chemoradiation-induced damage to the skin and soft tissues can cause complications following surgical reconstruction. OBJECTIVE To design an easily reproducible rodent rotational skin flap and to evaluate the effects of radiation exposure on flap viability. DESIGN AND SETTING Ten rats at a tertiary university medical center received 40-Gy irradiation to the abdominal wall. Following a recovery period of 1 month, a 3 x 8-cm fasciocutaneous flap based axially on the inferior epigastric vessel was raised and rotated 60 degrees into a contralateral deficit. Five nonirradiated rats underwent the identical procedure as a control. Animals were killed 7 days postoperatively, areas of flap necrosis were documented by an observer blinded to the grouping, and histological specimens were taken to compare flap viability and vessel density. MAIN OUTCOMES AND MEASURES Flap revascularization and microvascular density. RESULTS Six of 10 rats in the irradiated group had necrosis of the distal flap ranging from 1 to 6 cm from the distal edge, whereas none of the animals in the control group exhibited necrosis (P < .001). Histologic analysis revealed collagen and vascular changes in the irradiated skin. Vascular density analysis revealed a significant difference between radiated and nonradiated flaps; P = .004, .03, and .01 in the distal, middle, and proximal segments of the flap, respectively. CONCLUSIONS AND RELEVANCE This novel rat axial rotational flap model demonstrates increased flap necrosis and a decrease in vascular density due to the effects of radiation exposure. With use of a linear electron accelerator, a dose of 40 Gy can be delivered to the skin without resulting in devastating gastrointestinal adverse effects.