Purpose: Although it is acknowledged and intuitively assumed that end-to-end neurorrhaphy is the most desirable technique for repair of sectioned nerve; situations exist in which the proximal nerve stumps are not available. In these cases, end-to-side neurorrhaphy is a potential strategy. In this study, we examined the preservation of rat gracilis muscle mass after motor and sensory end-to-side neurorrhaphy.

Methods: Twenty-four Sprague-Dawley rats were used in the study. The study is divided into three groups. In group I (n=8), the rat gracilis muscle is denervated by transecting the obturator nerve. In group II (n=8), the gracilis muscle is reinnervated by coapting the proximal saphenous nerve (reported to be purely sensory) to the distal obturator nerve. In group III (n=8), the gracilis muscle is reinnervated by coapting the motor branch of the femoral nerve to the distal stump of the obturator nerve. At 6 months postoperatively, all rats were reexplored, the gracilis muscles were examined grossly, harvested and weighed individually.

Results: Gracilis muscles that were denervated along with those which were reinnervated with sensory nerves appeared grossly atrophic, thin bulk, pale in color, and with fibrosis. The muscles with motor nerve reinnervation retained good bulk and appearance compared to preoperative gracilis muscles. The muscle mass preservation in the motor-reinnervated group was 634.9±65.1 grams, which was significantly higher than the denervated group (457.5±125.3 grams, p<0.01). However, the muscle mass preservation in the sensory reinnervated group (606.9±209.1 grams) 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.

Conclusion: We conclude that muscle flaps can be successfully reinnervated by end-to-side neurorrhaphy. Muscle mass can be preserved by this nerve repair. Compared to end-to-side sensory nerve repair, motor nerve reinnervation is able to better arrest atrophic changes of the muscle flaps.