Fissure surgery is a procedure performed to treat a chronic anal fissure, which is a small tear in the lining of the anus. Chronic anal fissures typically don't heal on their own and can cause significant pain and discomfort.

2. Fistulas can be caused by a variety of factors, including:

Lateral internal sphincterotomy: This is the most common type of fissure surgery. In this procedure, a small cut is made in the internal anal sphincter muscle. This helps to relax the muscle and allows the fissure to heal. Lateral internal sphincterotomy is usually done as an outpatient procedure, which means you won't have to stay in the hospital overnight.

Sphincteroplasty: This is a less common type of fissure surgery that is typically only used if a lateral internal sphincterotomy has not been successful.