Lions rookie tight end Brandon Pettigrew left the team's loss to the Packers on Thursday afternoon with a knee injury. "I don't want to say too much until we get more tests," Detroit coach Jim Schwartz said after the game. "But it is something that we'll have to take a hard look at." Pettigrew's knee buckled while engaged with Packers linebacker Clay Matthews in the first quarter. He left and didn't return to the game.