Source: Team_Talk
O'Hanlon sidelined after surgery
The centre-back, 26, sustained the injury during the first half of Dons' 1-0 home defeat to Walsall back in April but he has now had to have surgery to rectify the problem.
The news now leaves the Dons needing fresh blood to fill the void left by a central defender who was included in the PFA's League One team of the year last season.
Assistant manager Karl Robinson told the club's official website: "Sean has had an operation and we're not looking to have him back until after Christmas.
"He's a great lad and we wish he was fit, but sometimes you've got to play the hand you've been dealt.
"We now need to get in a player who can perform to the same level that Sean has for the last three years."
