Swede Edman ruptured the anterior cruciate ligament to his left knee and will return to Sweden for surgery soon.
A club statement added: "It is a big blow for club and player, because Edman has been in sensational form since breaking into the side following his January move from Rennes."
Copyright (c) PA Sport 2008, All Rights Reserved.
Do YOU want to write for GiveMeSport? Get started today by signing-up and submitting an article HERE: http://gms.to/writeforgms