<qa>  How many patients will be implanted with medical devices?If a patient is suffering with symptoms of chronic FI despite trying oral medications, biofeedback andor other more conservative treatments, a patient may be eligible to participate in a clinical research study to evaluate the safety and effectiveness of sacral nerve stimulation for the treatment of chronic fecal incontinence. One hundred-twenty 120 patients will be implanted with medical devices and followed closely for twelve months, and then once a year after that until the study closes. There are up to 20 centers in the United States. 