Campbell suffered the injury when he blocked a slap shot by the Penguins' Evgeni Malkin during a Pittsburgh power play in the second period of Wednesday's 2-1 double overtime victory in Game 3 of the Eastern Conference finals at TD Garden.
After blocking the shot, Campbell remained on the ice for more than a minute in obvious pain and helped the Bruins kill off the penalty.
"The guy had a [shooting] lane and he sacrificed his body and it was a great thing," said Bruins goaltender Tuukka Rask. "It's a bad thing he got hurt. He blocks a lot of shots and he took one for the team there and we really wanted to win this for him."
Bruins coach Claude Julien said after the game he had no update but called it a serious injury and said the team would know more on Thursday.
"For what he went through, he showed a lot of guts to stay out there and to still try and play," Julien said. "Obviously it was a pretty serious injury, so that's just the kind of player he is, and it doesn't surprise me, it doesn't surprise his teammates, but certainly it shows the character of that player, and that's why we appreciate having him on our team."
Campbell's teammates appreciated his sacrifice. Here's what they had to say about Campbell:
Captain Zdeno Chara: "He's a man that he does whatever the team needs, and he's willing to sacrifice his body. For sure it was an outstanding block by him and you saw that the rest of the time he spent on that kill he was willing to do whatever he could on that one leg, so this one is for sure for him."
Winger Brad Marchand: "The fact that he took that shot and he couldn't even move and he was still trying to play and get in the lane, he did a great job. We really wanted to play for him, and it just shows his character. He's always battling. He's always doing whatever he has to do, and he's been huge for us this playoffs so far."
Center Patrice Bergeron: "It was a huge play by him. Again, we're talking about details, we're talking about little things that go a long way, and that block was super. That's the way he is. He sacrifices the body always for the team, for the better of the team. Obviously we tried to rally behind that and do it for him because he's a big part of our team on and off the ice. It was great, but at the same time we -- it was a tough game, we've got to make sure we're ready for Game 4."
Defenseman Andrew Ference: "You can't go into too much detail about it, but it's one of those ones that after the fact people are going to be pretty impressed with what he did. Obviously, you could see him block that shot and do everything he can to get in the way of the next passes and what not. I don't know how to describe it. You saw the next couple of shifts after that for us. Guys really got lifted up. It's amazing what guys can do in playoffs."
ESPNBoston.com's James Murphy contributed to this report.