ANAL-SPHINCTER RECONSTRUCTION WITH THE GLUTEUS MAXIMUS MUSCLE - ANATOMIC AND PHYSIOLOGICAL CONSIDERATIONS CONCERNING CONVENTIONAL AND DYNAMIC GLUTEOPLASTY

Myoplasties have acquired an important place in anal sphincter repair. The use of the gluteus maximus muscle for sphincterplasty was reporte d initially in 1902. However, in 1952, the gracilis sphincterplasty be came more popular because of the accessibility of this muscle. Unfortu nately, continence rates, especially after graciloplasty, remained unp redictable because of inability to maintain muscle contraction despite training programs. Training should induce a shift in muscle fiber typ e distribution toward a more fatigue-resistant composition, with predo minance of type I fibers. In order to obtain a more pronounced adaptat ion in the contractile, histochemical, and metabolic properties of mus cle fibers, postoperative intermittent long-term stimulation of the gr aciloplasty was performed. As these results and the results of dynamic cardiomyoplasty with an implantable myostimulator proved to be succes sful, implantable pulse generators were used after graciloplasty. Subs equently, continence rates after graciloplasties improved significantl y. These data encouraged us to perform dynamic gluteoplasties for anal sphincter repair. This paper presents the results in 7 patients treat ed by conventional and 4 patients treated by dynamic gluteoplasty. Adv antages and disadvantages of gluteoplasty were compared with those of graciloplasty. The neurovascular pedicle of the gluteoplasty underwent less traction after transposition compared with the graciloplasty bas ed on cadaver studies. Gluteus muscle transfer far exceeded the amount of muscle tissue of a normal anal sphincter despite muscle atrophy af ter transposition. This guaranteed a contractile muscle cuff around th e anal canal in contrast to the tendinous sling after graciloplasty. B ecause of the excellent vascularization of the muscle, microperforatio ns of the rectal mucosa caused by submucosal dissection were sealed, a nd implantation of electrodes and a pulse generator in one surgical in tervention was well tolerated. The myoplasty induced a double curvatio n of the anal canal in contrast to the graciloplasty, which enhanced t he natural anorectal angle. Patient evaluation revealed continence for stool in 9 of the 11 patients; 7 of the 11 patients also were contine nt for liquids, among them all of the patients who had undergone dynam ic gluteoplasties. Mean basal pressure after dynamic gluteoplasty was 49 mmHg, which is lower than the reported mean basal pressure (62 mmHg ) during stimulation after dynamic graciloplasty. Squeeze pressure aft er gluteoplasty, with or without stimulation, proved to be similar to or higher than that obtained in dynamic graciloplasty. Comparing our r esults of conventional gluteoplasty with the results of graciloplasty prior to stimulation, higher pressures were obtained by the gluteoplas ty, especially in squeeze pressures. In the last 5 patients intraopera tive pressure measurements were used to restore the optimal resting le ngth of the muscle after transposition. An intraluminal pressure of at least 40 mmHg during rest and 80 to 120 mmHg during stimulation shoul d be obtained to guarantee a future continent sphincter.