Coach Rex Ryan confirmed the injury Monday on his weekly radio appearance on ESPN Radio, adding that "we'll see" if McKnight can play.
It was not known when McKnight was injured during the Jets' 45-19 loss to the Philadelphia Eagles on Sunday. He played into the fourth quarter, but is also still healing from a hyperextended right elbow that sidelined him for a game.
McKnight, attending teammate Bart Scott's charity go-kart event at Pole Position Raceway on Monday night, said through a team spokesman that he preferred to not address the injury at that time because he was there with family for the event. His arm wasn't in a sling.
McKnight is the team's third-string running back, but as a kickoff returner he is averaging 32.3 yards a return, best in the league, and has a 107-yard touchdown. This is McKnight's second pro season.
Starting running back Shonn Greene injured his left pinkie during the game, and it was wrapped Monday night, but he said it was fine.
Copyright 2011 by The Associated Press