The team fears wide receiver
Green suffered the injury on the second play of the game. He had to be helped to the sideline and then carted to the locker room.
He was ruled out for the remainder of the game, and the Bengals lost 16-12 to fall to 3-6-1.
The five-time Pro Bowl selection entered Sunday ranked second in the NFL with 964 receiving yards.
Bills running back LeSean McCoy was ruled out for the remainder of the game with a thumb injury, and wide receiver Robert Woods also left the game with a knee injury.