That will make him miss Leeds' pre-season programme and he may also struggle to regain full fitness for the league opener against Exeter City.
Simon Grayson said: "He struggled last year with it and it was decided to have an operation. It's a blow because he's going to be out for six weeks or so, which means he could miss the start of the season.
"It's a massive disappointment. He was a massive player for us last season. He was an inspiration on and off the pitch, and he's disappointed.
"We decided to take this action now and hope he is fit, but it's touch and go. We have good physios and he'll do his rehab. He may be short on games when the season comes around, but we can cram a few in for him to bring up to speed."