Research on a novel flexible bionic artificial anal sphincter

Background: Artificial anal sphincter is a novel method for the treatment of fecal incontinence. Aiming at the problems of complex mechanical structure, high mechanical failure rate, large volume and poor biocompatibility of existing artificial anal sphincters, this article proposes a novel flexible artificial anal sphincter with bionic structure. Methods: A novel flexible artificial anal sphincter was proposed with bionic structure by analogy with the puborectalis, flexible transmission by flexible tendons, good biocompatibility by using thermoplastic urethane and medical silicone, small size and lightweight. The interaction between the rectum and the artificial anal sphincter is simulated by the finite element analysis, and the changes of the anorectal angle and the stress during the traction process of the rectum are analyzed. Results: The results suggest that the formed anorectal angle of <90 degrees may effectively control defecation, so the effectiveness of the artificial anal sphincter is preliminarily verified. When the traction angle was 71 degrees and the intestinal tube was basically closed, the maximum equivalent stress was 148.45 kPa, the maximum and minimum principal stress were 88.37 and 82.74 kPa, which were all below the safety pressure that initially verified the safety of the artificial anal sphincter. Conclusion: The novel flexible artificial anal sphincter may effectively reduce the stress between the device and the rectum and improve the biomechanical compatibility.