Muzzin left the game after blocking a shot from Victor Hedman shortly before the second intermission and did not return for the third period.
The 31-year-old has recorded 23 points in 53 games with the Leafs this season.
The native of Woodstock, Ont., signed a four-year contract extension with an average annual value of $5.625 million earlier this week.
In light of Muzzin’s injury, the Leafs recalled defenceman Calle Rosen from their AHL affiliate, the Toronto Marlies.
The 26-year-old Rosen was picked up in a trade with the Colorado Avalanche for goalie Michael Hutchinson at Monday’s deadline. He had two points in eight games with the Avalanche and 15 points in 35 games with their AHL team, the Colorado Eagles.
The Muzzin news is another blow to an already injury-plagued Leafs club, which is hoping to lock down a playoff spot in the Eastern Conference. The team is also missing fellow D-men Morgan Rielly and Cody Ceci, as well as forwards Andreas Johnsson and Ilya Mikheyev.