Postero-lateral Internal Sphincterotomy vs Botulinum Toxin Injection in the Treatment of Chronic Anal Fissure

We hypothesized that optimization of the dose of the Botulinum toxin injection (BT) and standardization of the technique of lateral internal sphincterotomy to posterolateral internal sphincterotomy (PIAS) could, in turn, report a conclusive result which helps to provide better care to patients with chronic anal fissure. So, we will conduct this trial as a prospective randomized, controlled, intervention, open-label trial with two parallel groups, and a primary endpoint of fissure healing during 6 months after the initial intervention, with the randomization, will be performed by an online software with a 1:1 allocation. Eligible patients will be randomized in equal proportions between BT injection and PIAS.