Experimental evaluation of an artificial anal sphincter based on biomechanical compatibility

Background: The artificial anal sphincter is a device used to treat patients with fecal incontinence who are unable to control their bowel movements on their own. Long-term morphological changes in the tissue surrounding the artificial anal sphincter can cause biomechanical compatibility problems, which seriously affect the clinical application of the artificial anal sphincter. Methods: In this paper, the superelasticity of shape memory alloys was utilized to design and fabricate a biomechanically compatible constant force clamping artificial anal sphincter. An in vitro simulation system was constructed to verify the effectiveness, safety, and constant force characteristics of the artificial anal sphincter. Results: The experimental results demonstrated that the artificial anal sphincter could be effectively closed with no leakage of the liquid-like intestinal contents, which are most likely to leak. The pressure of the artificial anal sphincter on the intestinal tube gradually increased and eventually became constant during closure, and the pressure value was always less than the intestinal blood supply pressure threshold. Conclusions: In this paper, we designed an artificial anal sphincter based on biomechanical compatibility and the corresponding in vitro simulation experimental program and preliminarily verified the effectiveness, safety, and constant force characteristics of the artificial anal sphincter.