The defenseman was injured during a 3-0 preseason win against the Montreal Canadiens on Wednesday, when he was cross-checked by Canadiens forward Rem Pitlick along the boards and left at 15:07 of the first period.
"Carl is going to require surgery," Toronto coach Sheldon Keefe said Friday. "It's going to be a six-month recovery, so bad news on that front."
Keefe also said forward Mitchell Marner, who had 97 points (35 goals, 62 assists) last season,
could be used as a defenseman
during the regular season.
Dahlstrom, who began the game on a defense pair with Victor Mete, had two assists in three games with the Maple Leafs last season and 14 assists in 49 games with Toronto of the American Hockey League.
In 67 NHL games with the Chicago Blackhawks, Winnipeg Jets and Toronto, he has 12 assists.
"I haven't seen him yet or spoken to [Dahlstrom] myself so I'm not quite sure (how he's taken the news)," Keefe said. "There's never a good time for such a thing but particularly when you've come off a summer of training and preparation and you are competing for a spot in the NHL, you get that news, it's difficult and of course it takes a shot at our depth as well, so that's not one you like to see."
Defenseman Jordie Benn, who began the game on a pair with Morgan Rielly, sustained a groin injury against the Canadiens on Wednesday and is expected to miss at least three weeks.
The 35-year old left the game at 9:13 of the first period.
"For Benn, he's going to be a minimum of three weeks so I guess we can look at that as positive news in the sense it is not as bad as initially thought," Keefe said, "but it's going to require some time to recover."
Benn, who signed a one-year, $750,000 contract with the Maple Leafs on July 14, had eight points (one goal, seven assists) in 39 games with the Minnesota Wild last season and has 135 points (25 goals, 110 assists) in 595 NHL games with the Dallas Stars, Canadiens, Vancouver Canucks and Wild.
