Peca suffered the injury in the first period of the Maple Leafs' 3-1 loss to the Chicago Blackhawks when he collided with Chicago defenseman Jim Vandermeer in a knee-on-knee collision at 14:43. Vandermeer was assessed a five-minute major penalty and a game misconduct.
"My legs were together and I turned out of the way," Vandermeer said. "We did hit knee on knee, but it was more him trying to get out the way then me throwing something out there to hit him."
In 34 games with Toronto this season, the 32-year old Peca has four goals and 11 assists.
"It's tough when you see a guy (Vandermeer) who can barely play in this league take out one of the best players in this league," Toronto center Jeff O'Neill said. "I don't know if he meant to do it or not, but this sucks for us."
Toronto coach Paul Maurice was not very happy with what transpired.
"The play happened on the other side of the ice, and I didn't get a good look at it," Maurice said. "I do know it was a knee-on-knee hit. Our guy will be out a long time and their guy will probably be in the minors by the time our guy gets back."