Comparison of Lateral Internal Sphincterotomy Techniques for Chronic Anal Fissure

Official title

A Prospective Randomized Controlled Trial Comparing Spasm-Controlled, Fissure Apex-Limited, and Dentate Line-Limited Lateral Internal Sphincterotomy Techniques in Chronic Anal Fissure

Overview

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.

Detailed description

Chronic anal fissure (CAF) is a longitudinal tear in the anoderm persisting for more than 8 weeks. Lateral internal sphincterotomy (LIS) is the gold-standard surgical treatment for CAF refractory to medical management, achieving healing rates of 90-98%. However, postoperative fecal incontinence remains its most significant complication, with rates ranging from 1-15% for permanent incontinence.

To reduce incontinence risk, various techniques limiting the extent of sphincterotomy have been proposed. Mentes et al. (2005) demonstrated that LIS up to the dentate line provided faster healing but caused significant continence disturbance, while LIS limited to the fissure apex was associated with lower incontinence but a higher treatment failure rate. Mentes et al. (2008) subsequently showed that spasm-controlled LIS using anal calibrators achieved faster pain relief with lower early incontinence rates compared to fissure apex sphincterotomy. However, no randomized trial has compared all three techniques simultaneously.

This single-center, prospective, three-arm RCT will enroll 150 adult patients with CAF refractory to at least 6 weeks of medical treatment. Patients will be randomized (1:1:1) to one of three groups: Group 1 (Spasm-Controlled LIS): serial small sphincterotomies under local anesthesia plus sedation until anal caliber reaches 30 mm using an anal calibrator. Group 2 (LIS up to Fissure Apex): open sphincterotomy extended to the proximal end of the fissure under spinal or general anesthesia. Group 3 (LIS up to Dentate Line): open sphincterotomy extended to the dentate line under spinal or general anesthesia.

All procedures will use the open technique with patients in lithotomy position. Randomization will be performed using computer-generated block randomization (block size 6), stratified by sex and fissure location. Outcome assessors will be blinded to group allocation.

Patients will be evaluated preoperatively and at postoperative day 1, week 1, week 2, month 1, month 2, month 6, and month 12. The Wexner (Cleveland Clinic) Incontinence Score will be used to assess continence at each visit. Fissure healing will be defined as complete epithelialization with no symptoms. Statistical analysis will follow the intention-to-treat principle, with Bonferroni correction applied for multiple comparisons.

Interventions

• Procedure Spasm-Controlled Lateral Internal Sphincterotomy
  Serial small open sphincterotomies under local anesthesia plus IV sedation using an anal calibrator until anal caliber of 30 mm is achieved.
• Procedure Lateral Internal Sphincterotomy up to Fissure Apex
  Open LIS extended to the proximal end of the fissure under spinal or general anesthesia.
• Procedure Lateral Internal Sphincterotomy up to Dentate Line
  Open LIS extended to the level of the dentate line under spinal or general anesthesia.

Primary outcome measures

• Fissure Healing Rate [Time frame: 12 months]
• Fecal Incontinence Incidence [Time frame: 12 months]

Secondary outcome measures (4)

• Postoperative Pain Score [Time frame: Day 1, Week 1, Week 2, Month 1, Month 2, Month 6, Month 12]
• Recurrence Rate [Time frame: Month 6 and Month 12]
• Patient Satisfaction [Time frame: Month 2, Month 6, Month 12]
• Postoperative Complications [Time frame: 12 months]

Eligibility criteria

Inclusion criteria

• 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)
• Primary anal fissure (posterior or anterior midline location)
• Written informed consent

Exclusion criteria

• 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
• Active anorectal infection (abscess or fistula)
• Pregnancy or breastfeeding
• Uncorrectable coagulopathy or current anticoagulant use
• Inability to cooperate with study procedures or attend follow-up visits

Criteria are shown verbatim from the registry (in English). Final eligibility is always assessed by the study center.

Healthy volunteers: No

Study design

Allocation

Randomized

Model

Parallel assignment

Masking

Single blind

Primary purpose

Treatment

Study locations

Turkey (Türkiye) · 1 center

• Canakkale Onsekiz Mart University — Çanakkale

Publications

• Elsebae MM. A study of fecal incontinence in patients with chronic anal fissure: prospective, randomized, controlled trial of the extent of internal anal sphincter division during lateral sphincterotomy. World J Surg. 2007 Oct;31(10):2052-7. doi: 10.1007/s00268-007-9177-1. PMID 17665247
• Mentes BB, Guner MK, Leventoglu S, Akyurek N. Fine-tuning of the extent of lateral internal sphincterotomy: spasm-controlled vs. up to the fissure apex. Dis Colon Rectum. 2008 Jan;51(1):128-33. doi: 10.1007/s10350-007-9121-3. Epub 2007 Dec 18. PMID 18085337
• Mentes BB, Ege B, Leventoglu S, Oguz M, Karadag A. Extent of lateral internal sphincterotomy: up to the dentate line or up to the fissure apex? Dis Colon Rectum. 2005 Feb;48(2):365-70. doi: 10.1007/s10350-004-0812-8. PMID 15711861

Identifiers

NCT: NCT07520552 · CAF-LIS-RCT-2026-01

Primary sources (government registries)

• ClinicalTrials.gov (US NIH)

View this study on ClinicalTrials.gov ↗