The loss of center Andy McDonald was a cruel blow for the Blues. Of all their surviving players, he was the one they could least afford to lose.

He is their No. 1 center. His speed and skill elevates the team. He led the team in scoring with 18 points in 16 games.

Coach Andy Murray praised him as the best Blue during the first 20 percent of the season.

McDonald made the power-play click. He kept this team viable after is lost puck-rushing defenseman Erik Johnson, then energetic rookie T.J. Oshie, then creative winger Paul Kariya.

Just when the Blues were coming back to life, by winning a thriller at Chicago and building a home-ice lead on Montreal, bad luck struck them again. He broke a leg crashing awkwardly into the boards.

This setback will not be easily overcome. Even with Kariya likely to return Friday, McDonald’s absence will have a crippling effect on the offense.

Look at the dominoes fall:

• With McDonald joining Oshie on the shelf, the Rams become a two-line offense instead of a three-line attack. More pressure falls on rookie center Patrik Berglund. Keith Tkachuk and Jay McClement must shoulder bigger loads.
• McDonald is a catalyst, one of those rare players who can make linemates better. Blues wingers will have fewer scoring opportunities and less room to work with Andy off the ice. This injury hit just as David Perron and Lee Stempniak were getting back on track. Expect lots of line shuffling as Murray struggles to build new chemistry.
• With Erik Johnson out, the Blues’ power player needed McDonald’s playmaking in a five-forward set to produce points. Andy held the group together, leading the team with 11 points with the man advantage. Expect a major falloff.
• The Blues’ lack of offensive organizational depth will be exposed. It’s great to see Cam Paddock and Steve Regier come up from Peoria to score goals, but that won’t last. They can help the team as fill-in grinders, but neither player possesses much offensive upside.

Even with McDonald playing well, the Blues were at even strength this season. Andy has a minus-12 rating this season and Brad Boyes is down to minus-14.

To survive this flurry of injuries, the Blues will need terrific team defense, awesome penalty killing (like we all saw Sunday) and tremendous goaltending.

Their margin for error evaporated. The challenge of getting back in the playoff became much, much greater.

The Blues will have to check like crazy. Manny Legace will have to steal some games again.

Their defensemen will have to clean up the play in their own zone and their forwards will have to quit taking chances.

There will be no easy way out of this crisis. It’s not like Mats Sundin woke up today and decided he wanted to help out the Blues by signing as a free agent.

Murray’s surviving players will just have to work their way out of this.

AROUND THE RINKS: The Capitals are looking to move center Michael Nylander, but the Blackhawks seem first in line to get him . . . Washington looks ready to go “all in” and add some additional skill. HockeyBuzz.com suggests that exiled Predator Alexander Radulov and Sabres winger Maxim Afinogenov could be in their sites . . . Old friend Brendan Shanahan hasn’t officially signed anywhere, but he seemed to be deciding between Philadelphia and New Jersey . . . Brian Burke could take the helm of the Maple Leafs sooner than later. His presence could convince Sundin to return home . . . If the Blues want to trade a defenseman for a forward, then John Davidson should check with the Senators before doing anything. Bryan Murray is looking to shake up that team.