Anatomic bases of graciloplasty using end-to-side nerve pudendal anastomosis

The objective of this study was to evaluate the possibilities of reinnervation of the gracilis muscle, transposed around the anus, by the pudendal nerve using an end-to-side nerve anastomosis. This study was carried out in 14 cases (7 adult human cadavers bilaterally). The gracilis muscle and its vascular-nervous bundle have been dissected and the nerve innervating the gracilis muscle has been cut at its origin. The gracilis muscle, accompanied by its nerve, has then been transposed around the anus. The pudendal nerve has been dissected from its extrapelvic part. The reinnervation using 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 extrapelvic part of the pudendal nerve. The extrapelvic part of the pudendal nerve has a common trunk in 12 cases. The width of the extrapelvic part of the pudendal nerve was 2.6+/-0.7 mm, range 1-3.5. The width of the proximal endings of the nerve innervating the gracilis muscle was 2.3+/-0.5 mm, range 2-3. The reinnervation of the gracilis muscle by the pudendal nerve has been possible in 14 cases. An average supplementary length of 17.4+/-15.4 mm was available (range 5-52). These results suggest an eventual practical aspect of this technique for the reconstruction of a functional sphincter using the gracilis muscle transposed around the anus.