According to the statement, Matthews has suffered a Grade 3 tear in the knee plus a bruised quadriceps in the second period of their game on Thursday versus the Anaheim Ducks.
Matthews was the victim of a knee-on-knee collision with Anaheim defenseman Radko Gudas. He needed assistance from the medical staff and a team-mate to get off the ice following the incident.
As for Gudas, he was handed a five-minute major penalty and a game misconduct during the clash, which the Leafs won 6-4. That was followed by a five-game suspension by the NHL Department of Player Safety, his fifth suspension of his career.
Judd Moldaver, Matthews' agent, was not pleassed to see that Gudas did not end up with an in-person hearing, which could have increased the duration of the latter's suspension.
"A phone hearing and five games is just laughable and preposterous," said Moldaver. "While the hearing process is pre-fixed in our CBA, that there was no further discipline is a reckless and ridiculous position for Player Safety.
"This decision results in a further loss of confidence in the disciplinary process for all players. Players and fans deserve better. The Player Safety department should be suspended."
Matthews recently captained the United States Olympic team to a gold medal in Milan-Cortina, There will be a re-evaluation in a couple of weeks to determine further steps.
The 28-year-old had scored in the win on Thursday before his injury, and will finish the year on 53 points (27 goals and 26 assists) across 60 matches.