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Comparison of Lateral Internal Sphincterotomy Techniques for Chronic Anal Fissure

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

Status
Recruiting
Phases
Unknown
Study type
Interventional
Source
ClinicalTrials.gov
Registry ID
NCT07520552
Acronym
SPHINX
Enrollment
150
Registered
2026-04-09
Start date
2026-05-06
Completion date
2028-05-06
Last updated
2026-05-14

For informational purposes only — not medical advice. Sourced from public registries and may not reflect the latest updates. Terms

Conditions

Chronic Anal Fissure

Keywords

Chronic anal fissure, Lateral internal sphincterotomy, Spasm-controlled sphincterotomy, Fecal incontinence, Dentate line, Fissure apex

Brief summary

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

PROCEDURESpasm-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.

PROCEDURELateral Internal Sphincterotomy up to Fissure Apex

Open LIS extended to the proximal end of the fissure under spinal or general anesthesia.

PROCEDURELateral Internal Sphincterotomy up to Dentate Line

Open LIS extended to the level of the dentate line under spinal or general anesthesia.

Sponsors

Çanakkale Onsekiz Mart University
Lead SponsorOTHER

Study design

Allocation
RANDOMIZED
Intervention model
PARALLEL
Primary purpose
TREATMENT
Masking
SINGLE (Outcomes Assessor)

Masking description

The surgeon performing the procedure is aware of the group allocation as blinding is not feasible for surgical technique trials. Patients are aware of their anesthesia type but are not informed of their specific group assignment until after the study. Data analysts will be blinded to group allocation during statistical analysis.

Intervention model description

Three-arm parallel group randomized controlled trial comparing three lateral internal sphincterotomy techniques (spasm-controlled, up to fissure apex, and up to dentate line) in a 1:1:1 allocation ratio.

Eligibility

Sex/Gender
ALL
Age
18 Years to No maximum
Healthy volunteers
No

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

Design outcomes

Primary

MeasureTime frameDescription
Fissure Healing Rate12 monthsComplete epithelialization of the anal fissure with no symptoms at 12 months postoperatively, assessed by clinical examination.
Fecal Incontinence Incidence12 monthsIncidence 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.

Secondary

MeasureTime frameDescription
Postoperative Pain ScoreDay 1, Week 1, Week 2, Month 1, Month 2, Month 6, Month 12Pain assessed using the Visual Analog Scale (VAS, 0-10) at each follow-up visit.
Recurrence RateMonth 6 and Month 12Proportion of patients with recurrence of anal fissure after an initial healing period.
Patient SatisfactionMonth 2, Month 6, Month 12Patient satisfaction assessed on a numeric scale (0-10) at follow-up visits.
Postoperative Complications12 monthsRate of surgical complications including bleeding, hematoma, infection, abscess, and fistula.

Countries

Turkey (Türkiye)

Contacts

CONTACTEmre Gülçek, MD, Assistant Professor
emre.gulcek@comu.edu.tr+905544810964

Outcome results

None listed

Source: ClinicalTrials.gov · Data processed: May 15, 2026