The 26-year-old suffered a multiple fracture to his right kneecap in a collision with Micah Richards during the Latics' 2-1 FA Cup quarter-final win over Manchester City on Sunday.
The news comes as a huge blow to Wigan, who face a Wembley semi-final against Arsenal next month and recently lost last season's FA Cup final goalscorer Ben Watson to a broken leg.
McCann is currently being examined by a specialist in London to determine whether he requires surgery.
Boss Uwe Rosler told the club's website: "It's a massive blow for us and for Chris, especially coming so soon after the injury to Ben Watson.
"We will do everything we can to make sure Chris gets back to action as quickly as possible and in the best physical condition he can be."