This prospective randomized controlled trial compares three lateral internal sphincterotomy (LIS) techniques in patients with chronic anal fissure refractory to medical treatment: (1) Spasm-Controlled LIS (serial small sphincterotomies using an anal calibrator until 30 mm anal caliber is achieved, under local anesthesia plus sedation), (2) LIS up to the Fissure Apex (spinal or general anesthesia), and (3) LIS up to the Dentate Line (spinal or general anesthesia). The primary outcomes are fissure healing rate and fecal incontinence incidence at 12 months, assessed using the Wexner Incontinence Score. Secondary outcomes include postoperative pain (VAS), recurrence rate, patient satisfaction, and complications. A total of 150 patients (50 per group) will be enrolled and followed for 12 months.
Age 18 years or older
Diagnosis of chronic anal fissure (duration ≥8 weeks)
Failure to heal after at least 6 weeks of appropriate medical treatment (topical agents, fiber supplementation, sitz baths)
Complete preoperative fecal continence (Wexner Incontinence Score = 0)
Any degree of preoperative fecal incontinence
Secondary anal fissure (associated with Crohn's disease, tuberculosis, HIV, syphilis, or other systemic conditions)
Previous anal sphincter surgery
History of obstetric sphincter injury
Parallel
Spasm-Controlled Lateral Internal Sphincterotomy
Procedure/SurgerySerial small open sphincterotomies under local anesthesia plus IV sedation using an anal calibrator until anal caliber of 30 mm is achieved.
Lateral Internal Sphincterotomy up to Fissure Apex
Procedure/SurgeryOpen LIS extended to the proximal end of the fissure under spinal or general anesthesia.
Lateral Internal Sphincterotomy up to Dentate Line
Procedure/SurgeryOpen LIS extended to the level of the dentate line under spinal or general anesthesia.
Fissure Healing Rate
Complete epithelialization of the anal fissure with no symptoms at 12 months postoperatively, assessed by clinical examination.
Fecal Incontinence Incidence
Incidence of de novo fecal incontinence assessed using the Wexner (Cleveland Clinic) Incontinence Score. A score increase of ≥1 point from preoperative baseline is defined as de novo incontinence.
Postoperative Pain Score
Pain assessed using the Visual Analog Scale (VAS, 0-10) at each follow-up visit.
Recurrence Rate
Proportion of patients with recurrence of anal fissure after an initial healing period.
Patient Satisfaction
Patient satisfaction assessed on a numeric scale (0-10) at follow-up visits.
Postoperative Complications
Rate of surgical complications including bleeding, hematoma, infection, abscess, and fistula.
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