Fissulyna wrote:

Posterior sphincterotomy was then replaced by lateral internal sphincterotomy either performed using a closed technique or under direct vision, under local or general anaesthesia. Studies have shown the results of the open and closed techniques to be similar.

I think that cut is never made INSIDE of the anus - it would mean making a brand new deep fissure on the opposite side !!!!
What they mean by "OPEN" is that it is done in "open view" !!! Muscle is separated from the colon and pulled out and cut is than made.
"CLOSED" is done by pushing the scalpel inside the tiny hole of the skin, between sphincter and outside tissue (regular muscle) and than just turned "blindly" like a key to make a cut in the sphincter. Than scalpel is turned back in "neutral" and pulled out !!!!
"Open" thus needs bigger opening in the skin by the OUTSIDE of the anus and more tissue separation
and thus leaves person with more pain and little bit longer healing.
BOTH are equally successful in giving a sphincter some release. : )))
NP LOL - you are "impossible"