The Finnish rearguard left midway through the second period of last night's 5-2 loss in Minnesota and didn't return.
"I think they call it an [anterior cruciate] first degree, so we're looking at probably a week," said Vigneault. "We have got to call up a defenceman. We're not quite sure yet who that's going to be."
The Canucks are already without Willie Mitchell, who suffered a concussion Oct. 21st in Nashville and has missed the past five games. He was only cleared to begin light workouts yesterday.
With Mitchell out, rookie Luc Bourdon's played five straight, but is averaging under nine minutes a game.
The Canuck will undoubtably lean on Mattias Ohlund, Kevin Bieksa, and Lukas Krajicek, but will need to call up an able body who can log regular NHL minutes.
"The logical choice if he wasn't hurt would be Yannick Tremblay," said Vigneault. "He'd be up here, but he's hurt for another two to three weeks."
The Canucks signed the 31-year-old free-agent defenceman this summer for exactly this reason, but sent him to Manitoba to start the year and lost him to a high-ankle sprain almost right out of the gate.
"I think the decision is going to be between [Joe] Rullier, [Alexander] Edler, and [Patrick] Coulombe...we should know by the end of today," said Vigneault.
Salo's injury puts a struggling Vancouver power play - currently ranked 26th in the NHL and scoreless in three straight - into an even deeper hole.
The hard-shooting Fin shares the team lead in power-play points with five, and is a key cog manning the point on the power play.
The Canucks finished 0-for-6 last night in Minnesota losing the special teams battle - and the game - because of it. The Wild went 3-for-4 with the man advantage and won 5-2.
"The only area that I'm obviously concerned about is our power play," said Vigneault after Thursday's game. "Our power play is not scoring and it has to find a way to do that."
"Everybody does their homework in the National Hockey League. Everybody knows the other team's tendencies and if you don't move it [the puck] and try to find a break somewhere, then you become really predictable. I think in some instances this year we have become a little bit predictable on the power play."
On the bright side, the new coaching staff will get a chance to further evaluate their young talent at the NHL level.
"Everybody want to play more and get more ice time and this is a great opportunity for the younger guys to show the coaching staff and themselves that they can handle more ice time," said Ohlund. "As much as we're going to miss the two guys that are injured, it gives some other guys an opportunity to play more."
Kevin Bieksa has five points and is a plus-one while averaging 21:14 a game. Lukas Krajicek has emerged as a top-four defender. He's a plus-four in just over 21:13 per game, and has helped the Canucks ice on of the best penalty-killing units through the first 12 games of the year.