The St. Louis Blues acquired defenseman Zbynek Michalek from the Arizona Coyotes on Monday for center Maxim Letunov and a conditional third-round pick in the 2015 NHL Draft. Michalek is scheduled to be an unrestricted free agent on July 1.

The Coyotes will retain 50 percent of Michalek's salary, according to ESPN.com.

Michalek has not played since Feb. 14 because of an upper-body injury believed to be related to a concussion. He told Sportsnet that he's feeling better and has been doing exercise for three days, but he isn't skating yet and doesn't know when he'll be ready to play for the Blues.

"I don't want to say something or promise something and not be able to play, so it's hard to say," Michalek said. "I'm hopeful that I'll be to play soon."

The Blues are in position to wait for Michalek to be healthy. They are second in the Central Division, four points behind the Nashville Predators and six points ahead of the third-place Chicago Blackhawks.

St. Louis is also deep enough on defense to wait for Michalek with Alex Pietrangelo, Jay Bouwmeester, Carl Gunnarsson, Barret Jackman and Ian Cole healthy and in the lineup. The Blues hope to have Kevin Shattenkirk and Michalek healthy before the Stanley Cup Playoffs begin.

Shattenkirk has been out since Feb. 2 because of an injury that required him to have abdominal surgery. He was listed out week-to-week but he has resumed skating and the Blues reportedly are hoping for him to return in mid-to-late March.

"Michalek was a guy we had a lot of interest in," St. Louis general manager Doug Armstrong told the Blues website. "We were close to getting a deal done before his injury, so that slowed things down. We got to a decision point last night that we were going to assume some risk on an injured player. He's a guy that can give us minutes and he's a guy that is comfortable defending against the other team's best players."

Letunov, 19, was a second-round pick (No. 52) of the Blues in the 2014 NHL Draft. He is playing for the Youngstown Phantoms of the United States Hockey League this season, where he has 22 goals and 53 points in 47 games.

"Maxim is a big, skilled center with excellent upside," Coyotes general manager Don Maloney said. "He will play at Boston University next season, who do a great job developing players. We are excited to have him join our organization."

Michalek, 32, was playing 21:05 per game for the Coyotes. He is 12th in the NHL with 130 blocked shots. He has eight points and a minus-6. Michalek was first among Arizona's defenseman with a 51.87 SAT percentage.

"I'm sure it wasn't an easy decision to do for the teams; I was out for two weeks and dealing with some injury," Michalek said. "I'm sure it's a big risk the team is taking on, but the same time I've been hearing rumors since Christmas that I'd be traded so it's not a big surprise for me. Right now the biggest thing for me is to get healthy. That's what I need to focus on."

The Coyotes also traded center Antoine Vermette and defenseman Keith Yandle in the past 48 hours.