The 28-year-old was diagnosed with a third-degree MCL sprain that will not require surgery, according to Hurricanes President and General Manager Jim Rutherford.
Staal's rehabilitation is expected to last three months and he should be ready to play at the start of next season.
Staal was injured when he took a knee-on-knee hit from defenseman Alexander Edler in the first period of Canada's quarterfinal game at the World Championships on Thursday in Sweden.
Staal arrived back at Raleigh-Durham International Airport Friday night and spoke exclusively to ABC11.
"I saw him coming and didn't really have anywhere to go, I was kind of planted," said Staal. "It was an unfortunate play. We'll see what happens here once I have an MRI and see what the results are. It didn't feel good at the time as I'm sure the people who watched it saw, but I'm feeling a lot better now. Hopefully, the results are OK and it's not too bad."
Edler received a five-minute major kneeing penalty and a game misconduct by the game's officials. On Friday, the IIHF Independent Disciplinary Panel determined that Edler should have received a match penalty as a result of the play and suspended him for the remainder of the tournament.
In his nine NHL seasons, Staal has missed just 14 games, and only 12 of those due to injury/illness, since the beginning of his rookie year of 2003-04.