Howard, acquired from Dallas on Feb. 13 in a seven-player trade, was playing in his fourth game with Washington.
He collided with Chicago's Flip Murray while trying to catch an outlet pass under Washington's basket with 4:23 to play in the first quarter Monday night. Howard fell on the floor, stayed there for a minute and was helped up as he clutched his left knee. Two trainers assisted him off the floor.
Howard had seven points when he was injured.