IRCT20171023036968N1 IRCT 2018-01-13 Arak University of Medical Sciences comparing the results and complications of chronic anal fissure surgery between open surgical sphincterotomy and closed surgical sphincterotomy comparing the results and complications of chronic anal fissure surgery between open surgical sphincterotomy and closed surgical sphincterotomy 2017-10-23 anticipated 100 Complete https://irct.ir/trial/27476 interventional Randomization: Not randomized, Blinding: Not blinded, Placebo: Not used, Assignment: Parallel, Purpose: Treatment, Randomization description: patients are randomi. N/A Chronic anal fissure. Intervention 1: first Intervention group: in this group patients will undergo closed partial lateral internal sphincterotomy. In this prosedure while nondominant index finger of surgeon is inserted in anal canal, number eleven surgical blade is inserted at dermal-anodermal junction distal to dentate line at three o'clock lithotomy position, then blade is rotated laterally and retracted with fourty five degrees lateral deviation. sufficiency of sphincterotomy and intactness of rectal mucosa is ascertained by digital examination and wound is hemostased and closed with chromic 00 sutures. Intervention 2: Secound Intervention group: in this group patients will undergo open surgery. In this procedure an incision, half to one centimeters long, is made on dermal-anodermal junction in inter sphincteric plane and internal sphincter is delivered to wound using a curved hemostat clamp and one third to one half of sphincter bulk is incised and the remainder is released to retract. sufficiency of sphincterotomy and intactness of rectal mucosa is ascertained by digital examination and wound is hemostased and closed with chromic 00 sutures. Undecided - It is not yet known if there will be a plan to make this available Justification or reason for indecision in sharing IPD is decision regarding sharing of data will be made after completion of sampling and gathering information.