The effect of pre-operative conventional and hyperfractionated radiotherapy schedules on wound healing and tensile strength in rats: an experimental study

Abstract

We examined the effects of pre-operative conventional and hyperfractionated radiotherapy schedules on wound healing and tensile strength in 90 female Wistar rats weighing between 182 and 240 g. The animals were randomized into three groups ( n = 30 each). Group I was sham-irradiated. Group II (conventional) received 20 daily fractions of 200 cGy, to a total dose of 4000 cGy. Group III (hyperfractionated) received 40 fractions of 120 cGy, twice daily, to a total dose of 4800 cGy. Four weeks after radiotherapy, incision and primary repair with simple suturing was performed on one side of the neck. Twenty-one days after wounding, all the rats were sacrificed. Non-parametric Kruskal–Wallis and Mann–Whitney U-tests were used for the statistical analysis of wound tensile strength. The chi-squared test was used for the statistical analysis of the histopathologic findings. The hyperfractionated group had a significantly lower tensile strength than that of the control group ( P = 0.03, z=–2.18). According to the histopathologic findings, fibrosis was increased significantly in the hyperfractionated group as compared to the other groups ( P = 0.038, χ 2 = 6.52). Hyperfractionated radiotherapy significantly reduced the wound tensile strength in the early evaluation period as compared to the control group.