Medical and Economic Evaluation of a Magnetic Anal Sphincter for Patients With Severe Anal Incontinence

Inclusion Criteria: * Adult patient (male or female) of 18 to 75 years of age * Affected by severe anal incontinence (SAI)\*. * Documented failure of conservative treatment (reeducation and medical treatment) * With functional anal sphincter\*\* * Agrees to take part in the study and has signed the informed consent form * Agrees to undergo post-operative surveillance for a period of one (1) year * Covered by National Insurance * Defined as follows: at least one involuntary passing of stool per week measured by collecting data on incontinence accidents on a 3-week stool record chart, with the continence problem developing over more than 6 months. \*\*Defined as follows: external sphincter intact (without injury or after sphincter repair) or external sphincter altered, with an injury of a size that does not justify sphincter repair. Internal sphincter injuries not taken into account (by professional consensus). Exclusion Criteria: * Anorectal or pelvic malformations * Local conditions incompatible with the proposed sizes of the MAS (extreme obesity, thickness of the tissue in the anorectal area) * Sequelae of rectal resections - presence of cancer of the rectum or anus * Rectal prolapse and/or major pelvic floor disorders * Major chronic disorder of the intestinal motility, irritable bowel syndrome, repeated faecalomas, megarectum * Extensive sphincter degeneration * Consequences of radiation-induced rectitis and chronic inflammatory diseases of the bowel (Crohn's disease) * Neurological disorders or systemic diseases (multiple sclerosis, scleroderma, paraplegia) * Festering sores of the perineal and/or anorectal regions * Known or suspected risks of allergy to titanium * Active pelvic infection * Contraindications to SNS: * Cardiac stimulator or defibrillator implant * Malformation of the sacrum * Patient exposed to Magnetic Resonance Imaging * Skin diseases exposing the patient to the risk of infection (at the investigator's discretion) * Patient scheduled for diathermy or ablation by radiofrequency * Pregnant women * Adults under guardianship * Patients involved in a mobility project in the year following the operation * Patient already subjected to one or other of the therapeutic approaches (MAS or SNS) Please note: coagulation problems (including anti-aggregant or anti-coagulant treatments) are not a contraindication if these problems can be corrected during the perioperative period.