(Reuters) - Carolina Hurricanes defenseman Joni Pitkanen underwent surgery on his left knee on Tuesday and is expected to miss about four weeks, the National Hockey League (NHL) team said.

The 28-year-old Pitkanen, who was out indefinitely with a concussion suffered in December, has three goals and nine assists in 21 games this season and leads all Carolina players in average ice time.

The absence of the Finnish defenseman, who was the team's top-scoring defenseman when he was sidelined in December, is a blow for a team that is already sitting in last place in the NHL's Eastern Conference.

Pitkanen, who was taken fourth overall in the 2002 NHL Draft by the Philadelphia Flyers, has 268 points in 504 career games with Carolina, Edmonton and Philadelphia.

(Reporting by Larry Fine in New York; Editing by Frank Pingue)