Reconstruction of the anus by the gracilis muscle reinnervated by the pudendal nerve. A preliminary anatomical study

UNLABELLED: The aim of this study is to evaluate the possibilities of reinnervation of the gracilis muscle, transposed around the anus, by the pudendal nerve with an end-to-side nerve anastomosis. METHODS: This study was carried out in 10 cases. The gracilis muscle and its vascular-nervous pedicle have been dissected. The nerve of the gracilis muscle has been cut at its origin. The gracilis muscle was transposed around the anus. The nerve of the gracilis muscle was transposed in the gluteal area. The pudendal nerve has been dissected from its extra-pelvic part. The reinnervation with an end-to-side nerve anastomosis has been considered as feasible when the proximal ending of the nerve of the gracilis was put into a tension free contact with the extra-pelvic part of the pudendal nerve. RESULTS: The reinnervation of the gracilis muscle by the pudendal nerve has been possible in all cases. The extra-pelvic part of the pudendal nerve has a common trunk in 8 cases. The width of the extra-pelvic part of the pudendal nerve was 2.8 +/- 0.8 mm (1-3.5). The width of the proximal endings of the nerve innervating the gracilis muscle was 2.5 +/- 0.5 mm (2-3). After transposition of the nerve of the gracilis muscle in the gluteal area an average supplementary length of 20.9 +/- 16.8 mm was available (range 5-52). CONCLUSIONS: These results suggest that a reconstruction of the anal sphincter with a gracilis muscle transposed around the anus and reinnervated by the pudendal nerve with end-to-side nerve anastomosis is possible.