Early in the second period of Sunday's 2-1 win, Powe had an accidental collision with Capitals forward Matt Hendricks in the neutral zone. Hendricks and Powe did not see each other until the last second, resulting in Powe flipping over Hendricks and hitting his head on the ice.
Powe stayed down for several minutes and was eventually helped off the ice by teammates. He did not return to the game.
To take Powe's roster spot, the Rangers recalled Brandon Mashinter from the Connecticut Whale of the AHL.
Rookie forward Chris Kreider, out of the lineup the past two games as a healthy scratch, could return to the lineup in Powe's absence.