Anatomic basis of anorectal reconstruction by dynamic graciloplasty with pudendal nerve anastomosis.

Abstract

Dynamic graciloplasty has been proposed for anal reconstruction, but this method has 2 major drawbacks. First, an electrical device is required for control of the gracilis. The anastomosis with the pudendal nerve will provide more physiological control. Second, the limitation in the mobility of the muscle flap results in wrapping the anal canal with the muscle's distal portion, which is tendonlike and inelastic. Enhancing the mobility of the muscle flap will enable wrapping with the proximal, muscle-like, and extensible portion, possibly providing better sphincteric function. However, the basis for such an operative method is lacking. The aim of this study is to provide the basis for the refined method of anal sphincter reconstruction by dynamic graciloplasty with pudendal nerve anastomosis and to verify the feasibility of lengthening the nerve to the gracilis muscle flap by dissecting into the muscle belly, detaching the gracilis muscle from its origin, and enhancing the mobility of the muscle flap. This is a retrospective, descriptive study. The results from the anatomical study on 9 cadavers are reported. Tension-free anastomosis of the pudendal nerve and nerve to the gracilis was successfully performed in all the 9 cases: in 2 cases, by lengthening the nerve. The detachment of the muscle origin improved the mobility of the muscle flap, and the more proximal portion could be used for wrapping the anal canal, as confirmed in 4 cases. The limited number of cases was a shortcoming of this study. By lengthening the nerve to the muscle, the gracilis can be used for anal sphincter reconstruction with pudendal nerve anastomosis, negating the need for an electrical device. By detaching the origin of the gracilis muscle, its proximal portion can be used to wrap the anal canal, possibly enabling a longer functional canal with stronger constricting force and better vascularity. These modifications to past methods may improve fecal continence after the operation.