Arroyo 2004.

Methods	Randomized Controlled Trial
Participants	Chronic anal fissure
Interventions	Open (40) versus "closed" (40) lateral internal sphincterotomy under local anaesthesia
Outcomes	Persistance, recurrence, healing up to 2 years and manometry pre‐operative, and at each f/u: 20 days, 6 months, 1 year, 2 years Continence assessment by Wexner score
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	adequate
Blinding of outcome assessment (detection bias) All outcomes	High risk	not stated
Drop‐outs All outcomes	Low risk	zero