Phaneuf got tied up with Ottawa's Peter Regin just after the six-minute mark of the second period of Tuesday's game against the Senators and fell awkwardly. He suffered a cut deep enough on his left leg that he had to be helped off the ice and was taken immediately to a local hospital.
According to TSN's Darren Dreger, surgeons found "a nick" to the medial collateral ligament in Phaneuf's knee, which required "a few stitches to repair."
Following Tuesday's game, coach Ron Wilson said Brett Lebda likely will take Phaneuf's place in the lineup Wednesday in Washington (7 p.m. ET, NHLN-US, TSN).
"You can't replace Dion and what he brings to the team, but other people will have to step up in a leadership role and be vocal," Wilson told reporters following the Leafs' 3-2 loss to the Senators. "We've got a deep defense. Some guys will get some more minutes. We should be able to weather the storm."
"You're talking about a real small number of people and frankly I think it's a disgrace," Burke told reporters before Phaneuf got hurt. "Ten games in and I don't think I've ever had a player booed. I think it's really unfair to Dion because of the things he's brought. The mistakes he's made generally happen when we're behind and he's trying to make something happen.
"He's given us solid defensive-zone coverage. He's almost single-handedly changed the culture of our team."
To replace Phaneuf on the roster, the Leafs have called up Korbinian Holzer from the AHL Toronto Marlies. Holzer, a 2006 fourth-round pick from Germany playing his first season in North America, is scoreless with a minus-5 rating and 17 penalty minutes in eight AHL games.
Follow Dan Rosen on Twitter at: @drosennhl