Hartnell, an All-Star last season, was injured by a shot taken by teammate Kimmo Timonen in Tuesday's game against New Jersey. Flyers general manager Paul Holmgren made the announcement before Thursday night's game against the New York Rangers.
Hartnell had one point in three games. He led the Flyers with 37 goals last season and had 67 points.
The Flyers are still without forward Danny Briere (broken left wrist). Holmgren says it's 50-50 Briere will be available for this weekend's games at Florida and Tampa Bay.
I remember the first time at Wrigley Field all of us had the long johns, the turtlenecks and the extra equipment because we were afraid of being cold. Halfway through the first period everybody's ripping everything off and we just ended up wearing what we would normally wear for a game at the United Center.
— Chicago Blackhawks forward Patrick Sharp on the 2009 Bridgestone NHL Winter Classic