Arlington, VA -- (Sports Network) - The Washington Capitals signed defenseman Mike Green to a four-year contract extension on Tuesday, preventing him from hitting the open market as a restricted free agent.

Per club policy, financial terms of the deal were not disclosed.

Green, 22, enjoyed a breakout season in 2007-08, tallying 18 goals -- most among NHL defensemen -- and 56 points as one of only four Caps players to take the ice in all 82 regular-season games. The Calgary native also notched three goals and four assists in Washington's seven-game Eastern Conference quarterfinal loss to the Philadelphia Flyers.

"Mike has developed into an impact defenseman in the short time since we drafted him, and he will be a key part of our team moving forward," said Capitals general manager George McPhee. "We look forward to his further contributions as we continue to improve the hockey club."

A first-round draft pick in 2004, the 6-foot-2 defenseman had just three goals and 12 assists in 92 games over his first two NHL seasons before flourishing under new Caps head coach Bruce Boudreau, who coached Green when he played with the Hershey Bears of the American Hockey League.