Updated

DENVER (Reuters) - The Colorado Avalanche acquired former top draft pick Erik Johnson as part of a four-player trade with the St. Louis Blues on Saturday.

The Blues also sent forward Jay McClement and a first-round pick to the Avalanche for right wing Chris Stewart, defenseman Kevin Shattenkirk and a second-round draft choice.

"We are excited to be adding a top young defenseman in this league, a player who will have an impact on our blue line for several years to come," Avalanche general manager Greg Sherman said in a statement.

Johnson, drafted first overall in 2006 and winner of a silver medal with the United States at the Vancouver Olympics, has five goals and 14 assists in 55 games this season.

McClement has 16 points in 56 games.

Stewart, limited to 36 this season because of injury, had 13 goals and 30 points with Colorado while Shattenkirk is second among rookie defenseman with 26 points in 46 games.

"We're very excited to acquire a young emerging power forward in Chris Stewart and a top young NHL defenseman in Kevin Shattenkirk," said Blues executive vice president and general manager Doug Armstrong.

"These are two solid young players which will help us now and continue to grow and improve our team."

The two draft picks included in the trade are for either the 2011 or 2012 NHL Draft.

(Reporting by Mike Mouat in Windsor, Ontario; Editing by Frank Pingue)