Anal fistulae are a difficult problem to treat. The optimal treatment for fistula involving the anal sphincter is unclear. Two standardly used methods of treatment are the ligation of intersphincteric fistula track (LIFT) procedure and the use of an anal fistula plug. The purpose of this study is to exam the rate of fistula closure between the LIFT procedure and the use of a fistula plug

Inclusion Criteria:

• Male or female subjects 18 years of age or older.
• Able to understand and provide informed consent or have a legally authorized representative capable of providing consent.
• Has a documented diagnosis, confirmed by physical exam and/or endorectal ultrasound (if available), of a trans-sphincteric fistula tract determined to be of cryptoglandular origin (primary or recurrent).

Exclusion Criteria:

• History or suspicion of Inflammatory Bowel Disease (Crohn's or Ulcerative colitis).
• History of connective tissue disease.
• Rectovaginal fistula.
• Presence of horseshoe fistula.
• History of immunosuppression therapy/treatment within previous six months.
• Presents of a proximal diversion and refractory fistula.
• Any physical conditions, disease, or disorder that would exclude subject from being a candidate for elective surgery.
• Known history of allergy to pork or pork products.