Muscle flap mass preservation with end-to-side neurorrhaphy: an experimental study

The authors examined the preservation of rat gracilis muscle flap mass after motor and sensory end-to-side neurorrhaphy. The rat gracilis muscle flap model was designed based on a previous study. Twenty-four Sprague-Dawley rats were divided into three groups. In Group 1 (n = 8), the flap was denervated by transecting the obturator nerve. In Group 2 (n = 8), the flap was reinnervated by coapting the proximal saphenous nerve to the distal obturator nerve. In Group 3 (n = 8), the flap was reinnervated by coapting the motor branch of the femoral nerve to the distal stump of the obturator nerve. At 6 months postoperatively, the gracilis muscle flaps were examined, harvested, and weighed individually. Results showed that the flaps with motor nerve reinnervation retained good bulk, with a weight of 634.0 +/- 65.1 gm, which was statistically significantly higher than the denervated group (457.5 +/- 125.3 gm, p < 0.01). However, muscle mass preservation in the sensory reinnervated group (606.9 +/- 209.1 gm) was not significantly different, compared to the denervated group. Histology revealed atrophic changes in the denervated group, compared to the sensory and motor-reinnervated groups. The authors concluded that muscle mass can be preserved by end-to-side nerve repair. Motor nerve reinnervation is able to better arrest atrophic changes of the muscle flaps.