The Bruins said McAvoy's injury will be re-evaluated in four weeks.
"We'll be without Charlie for a little bit but we've got lots of depth and he will be back," Boston coach Bruce Cassidy said. "… Hopefully he heals quick and keeps his conditioning up."
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McAvoy, 20, has 32 points (seven goals, 25 assists) in 59 games and averages 22:06 of ice time per game, second on the Bruins to defenseman Zdeno Chara (23:11).
The Bruins had Brandon Carlo in McAvoy's spot with Chara at the morning skate Tuesday. The other pairs were Torey Krug and Nick Holden, and Kevan Miller with Matt Grzelcyk.
"I think just the rest of the guys as a whole need to be ready to play a few more minutes, but at the same time don't get away from what we've been doing successfully this whole year," Grzelcyk said. "So keep it simple, but if you can create a four-man attack, it'd be huge, especially without Charlie in the lineup. We're obviously going to miss him but we've got to do our part."
The Bruins also are missing forward Patrice Bergeron and goaltender Tuukka Rask. Bergeron has a fractured right foot sustained against the Toronto Maple Leafs on Feb. 24 and is scheduled to be re-evaluated next week. Rask has a lower-body injury and won't play against the Detroit Red Wings at TD Garden on Tuesday (7 p.m. ET; NBCSN, SN, TVAS, NESN, NHL.TV).
Cassidy said Rask skated Tuesday but is unsure if he'll be available to back up Anton Khudobin.
"[Rask] is feeling better," Cassidy said. "We'll make a decision after the skate, talk to Tuukka, and if he feels if he had to go in and he could do it, he would back up. Otherwise we would look at a goaltender from Providence (American Hockey League)."
The Bruins (40-15-8) are second in the Atlantic Division, three points ahead of the third-place Maple Leafs.
