Ref (type)	Population	Outcome, Interventions	Results and statistical analysis	Effect size	Favours
Adverse effects
Systematic review	336 people with chronic anal fissure 5 RCTs in this analysis	Minor flatus incontinence 15/168 (9%) with open lateral internal sphincterotomy 17/168 (10%) with closed partial lateral internal sphincterotomy	OR 0.87 95% CI 0.41 to 1.83 P = 0.71		Not significant