Edman suffered a suspected rupture of the anterior cruciate ligament in his left knee during Saturday's 3-1 defeat at Blackburn.
The injury will keep him sidelined until the autumn, ruling him out of the Sweden squad for Euro 2008 as well as Wigan's bid to stay in the Premier League.

He was injured blocking a header from ex-Latics striker Jason Roberts,
landing awkwardly on his left leg and twisting.
Play was held up for four minutes while he was treated by the Wigan
medical staff and then taken off on a stretcher.
While Edman faces up to nine months out, Latics will go to Portsmouth this weekend without both their first-choice centre midfield players.

Wilson Palacios was sent-off in the second half at Ewood Park for two
bookings, earning him a one-match suspension.
And it's a two-game ban for Michael Brown after he collected his 10th yellow card of the campaign – he also misses the home clash against Birmingham on April 5.

With Jason Koumas currently serving a three-match suspension, the squad suddenly looks thin on the ground in midfield.
But the main concern is Edman, who left Blackburn on crutches and is expected to have the extent of the damage diagnosed by a specialist in the next couple of days.

Latics boss Steve Bruce said: "It looks like Erik will be out until September or October.
"He has been crucial to us, rock solid since coming into the team. When he went off it changed the game.
"I think it affected us badly as we had a nice balance with him in the team which we obviously lost.

"We've suddenly found ourselves with a few injuries and suspensions.
"Palacios and Brown are suspended now, Koumas already was, Antoine
Sibierski was injured and now Edman is.
"That is what we have a squad for and we'll start assessing today how we'll manage in the coming games."

Latics striker Emile Heskey has wished Edman a speedy recovery, and admitted that the seriousness of the injury wasn't immediately
noticeable.
He said: "Erik has been very unlucky.
"He made a great block from Roberts' header and everyone played on, but then we saw he was still lying on the floor so we realised there was
something wrong.

"I hope he gets better soon. He has been great for in the last few weeks and it is a blow to lose him."
Another Latics player in the wars was Chris Kirkland who hurt his back
inside the first three minutes, although did manage to complete the game.
Kirkland last night pulled out of the England squad to play France in Paris on Wednesday and will instead have treatment in Wigan in the hope of being fit for the Pompey game.

He has been replaced in Fabio Capello's squad by West Ham's Robert Green.
Bruce said: "Kirky was moving very gingerly because of his back in the dressing room afterwards."
The visit to Blackburn proved eventful, with Rovers reduced to 10 men after 16 minutes when Chris Samba was
red-carded for a foul on Heskey when he was clear on goal.

Marlon King slotted home the resulting penalty, equalising Roque Santa Cruz's early opener for the hosts.
But having the numerical advantage didn't help Latics, with Rovers going 3-1 ahead through Roberts and Santa Cruz before Palacios' dismissal evened the sides out.