Hartman was controlling the puck with his back to Kruger when he cocked back his left elbow and hit the Chicago veteran in the face. Kruger fell to the ice and left a trail of blood on the United Center ice as he was helped off the ice by an official with 3:29 left in the second frame.
Kruger did not return for the third period.
It’s the second concussion in as many games and third in less than two weeks for Chicago, who currently have star goaltender Corey Crawford in concussion protocol after a collision in Sunday’s game against San Jose. The Blackhawks also activated center Artem Anisimov from injured reserve after he missed four games with a concussion.
Kruger has four goals and an assist in 33 games this season.