"We will know more on this within a day or two as we await results of tests," Holmgren said in announcing the injury.
Hartnell saw 17:13 of ice time in the Flyers' 3-0 loss at the New Jersey Devils on Tuesday. He has one assist and 13 penalty minutes in three games this season.
The Flyers will be without Hartnell, Brayden Schenn and Zac Rinaldo for Thursday's home game against the New York Rangers. Schenn was suspended by the NHL for one game for a hit on New Jersey defenseman Anton Volchenkov in Tuesday's game, and Rinaldo is out with a lacerated right thigh.
Not only is it a great idea, but if you don't [start using analytics] you're going to fall behind. You have to be on the cutting edge. It was [Arizona Coyotes assistant general manager] Darcy Regier who said, 'If you didn't invent it, you have to be the second- or third-best copier, because if you're fourth or fifth you've got no chance.'
— Detroit Red Wings coach Mike Babcock on his interest in advanced statistical analysis