Progress on Bionic Artificial Anal Sphincters Based on the Physiological Defecation Mechanism.

Area of Science:

• Biomedical Engineering
• Gastroenterology
• Reconstructive Surgery

Background:

• Fecal incontinence (FI) significantly impacts patient quality of life.
• Artificial anal sphincters (AASs) are a surgical option for severe FI.
• Current AASs face limitations due to biomechanical incompatibility with host tissues.

Purpose of the Study:

• To review defecation physiology for bionic AAS design.
• To classify and compare existing AAS device types.
• To identify biomechanical challenges and future optimization strategies for AAS.

Main Methods:

• Review of physiological defecation mechanisms.
• Classification of AAS into angle-regulation and direct occlusion types.
• Comparative analysis of biomechanical failure modes for each AAS type.

Main Results:

• Angle-modulating AASs can cause tissue hyperplasia.
• Direct occlusion AASs risk tissue erosion, infection, and breakdown from pressure.
• Biomechanical incompatibility is a primary cause of AAS complications.

Conclusions:

• Harmonizing mechanical function with the biological environment is crucial for AAS safety and efficacy.
• Novel designs like constant-force mechanisms and smart sensing/AI integration are promising.
• Biohybrid designs integrating tissue engineering may offer superior long-term integration for AAS.