Ligation of the Intersphincteric Fistula Tract (LIFT) + Biodesign for Anal Fistula

Inclusion Criteria: * Persistent primary or recurrent trans-sphincteric anal fistula Exclusion Criteria: * Patients with prior fistulotomy, fistulectomy, LIFT, cutting seton or advancement flap procedure * Fistula with multiple tracts * Recto-vaginal fistula * Active infection in the anal fistula * Physical allergies or cultural objections to porcine products * Patient is not medically fit to undergo the LIFT procedure as judged by the treating physician * Previous diagnosis of collagen disorder * History of Crohn's Disease, Irritable Bowel Syndrome, radiation therapy in the rectoanal region