Magnetic sphincter for anal incontinence: an update

The idea of using magnets to control the esophago-gastro-intestinal flow of contents dates back almost 20 years, from the first bench experiment in 2003, published in 2006, while the first clinical application at the anal level to prevent fecal incontinence took place in 2010 by means of a device called FENIX magnetic anal sphincter augmentation (MAS). The clinical experiences with MAS ranged from satisfactory success to partial failure depending on the various studies. The nonrandomized comparisons of MAS with sacral nerve stimulation (SNS) and artificial bowel sphincter (ABS) showed a similar effectiveness in fecal continence and quality of life, whereas the adverse events were more frequent and severe with MAS compared to SNS. ABS either failed to work or required an explantation for infection in 40% of patients, whereas MAS showed these adverse events in only 20% of cases. The comparison of MAS with anal slings and bulking infiltrations provided similar continence results, although with a shorter duration, whereas MAS showed more adverse events. Recently MAS has been withdrawn from the market, creating major inconveniences for surgeons and patients. Nevertheless, this can represent an opportunity for a system that reinforces the anal sphincter with "two magnetic plaques" to be finally implemented for use in patients after completing animal experimentation. This system offers various advantages compared with MAS: it has simpler operational activity, easier surgical implanting procedure, the possibility of "tailored" sphincter augmentation, and should turn out to cost less.