Experimental model for transplantation of a modified free myocutaneous gracilis flap to an irradiated neck region in rats

Abstract

Abstract.In 102 Wistar rats (male, weight 300–500g), a modified free myocutaneous gracilis flap was obtained from the groin and transplanted to the neck. To create a pre-irradiated transplant bed, a local area of the neck was irradiated preoperatively with 30Gy (fractionation: 3×10Gy) in 30 animals, and with 50Gy (fractionation: 5×10Gy) in a further 30 animals. The interval between preoperative irradiation and transplantation was 4 weeks. Forty-two animals received no such preoperative radiation. The evaluation of healing and the success of the transplanted flap was based on a clinical assessment, carried out on postoperative days 1–7. Testing for significant differences was done nonparametrically using the Kruskal–Wallis test. The survival rate in the nonirradiated animals was 86%. In contrast, the healing of the free flaps in the pre-irradiated transplant bed was significantly lower (P=0.003) 76%, after irradiation with 30Gy and 50% after 50Gy. The significant difference (P=0.020) in survival rates after irradiation with 30 and 50Gy was evidence for the dependence of successful healing on the preoperative radiation dose. Transplantation of the free myocutaneous gracilis flap to a previously irradiated transplant bed in the region of the neck is a suitable model for investigating the healing of free transplants to irradiated tissue. The success rate observed in non-irradiated transplant beds is comparable to that seen with other flap models in rats.