Functional perineal colostomy with pudendal nerve anastomosis following anorectal resection: A cadaver operation study on a new procedure

Abstract

Background. We have previously studied functional perineal colostomy that used skeletal muscle with pudendal nerve anastomosis (PNA) following anorectal resection in an animal model. In that study the neosphincter reconstructed with PNA achieved the proper functions of the external anal sphincter resulting in a satisfactory defecatory condition. This study was a preliminary step before applying this procedure to human beings. Methods. We reconstructed a new anal sphincter by using the lower part of the glutens maximus muscle (lower GMM) with PNA in a total of six sides of four human cadavers and investigated the anatomic problems associated with this procedure. Results. We classified the branching patterns of the inferior gluteal nerve into three types. The length of the branches of the inferior gluteal nerve to the lower GMM varied from 32 to 76 mm (median, 57 mm). The length of the pudendal nerve (PN) passing out below the sacrotuberous ligament varied from 21 to 44 mm (median, 29.5 mm). The PN was anastomosed to the nerve innervating the lower GMM with the redundancy of 17 to 36 mm (median, 24.5 mm). In all cases the anal sphincter reconstruction with a PNA maneuver was anatomically feasible by using the lower GMM. The length of the new anal canal was 65 to 80 mm (median, 67.5 mm). Conclusions. The PNA maneuver was an anatomically applicable method to make a neoanus in human beings. Preparation for the application of this method to human beings was accomplished.