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 don't think it's really truly going to sink in until we drop the puck, to be honest. I know there's going to be a lot of smoke and mirrors with the media attention and all that. We came [Monday] and it was sort of a light day to get things organized. We just want to focus in on the business aspect, the game itself. That's what we're preparing to do. Get these next couple of days out of the way and it's game on.
— Lightning captain Steven Stamkos on playing in his first Stanley Cup Final