Philadelphia Flyers defenseman Travis Sanheim (28), a healthy scratch for Wednesday's game, will fill in for Theodore going forward.
Theodore only played six minutes before getting hurt.
"It's heartbreaking for the kid," said Canada head coach Jon Cooper. "And he was the first one there at the door high-fiving everybody when we came off. It's a tough one to swallow because you just know how much it means."
"But for us it was tough because you talk about the speed in that game, and we had to fight through the last 50 minutes with five defensemen. That's a grind."
What Canada can do
Canada cannot bring on another defenseman for their team unless they fall under six. However, the team is currently working with the NHL and NHLPA to work on an emergency solution.
According to the league, Canada can bring on board an emergency defenseman but the player has to remain in the Boston area (one of two locations for the tournament) and cannot practice with, or even be with, the team.
The player will also not be officially be on the team unless another unfortunate injury happens and they fall below the six-defenseman minimum. Canada is still working on a solution with the league.
(Update: Dallas Stars' defenseman Thomas Harley has been named the emergency player for Team Canada.)
Theodore is considered week-to-week after sustaining the injury that left him grabbing his wrist, which sideline reporter Jackie Redmond said was swollen.
Canada ended up beating Sweden 4-3 after an overtime goal by Mitch Marner.
Sanheim's opportunity
Sanheim is embracing the role that's now his for the rest of the tournament. His first game? Against the United States on Saturday.
"It's been something that I've dreamt of doing," said Sanheim. "I'm very excited. I just said (to everyone) that I'd be ready if they needed me."
Sanheim reassured that whichever side of the ice the coaches needed him to play on, he would play without hesitation.
Theodore is a huge blow to both Canada's defense and their powerplay unit, so Sanheim is going to have to pull through against the toughest test possible with the United States' stacked forward lines.