Roethlisberger remained in the game, playing through what coach Mike Tomlin labeled a foot sprain after the win.
"My foot was in the ground and someone was driving me backwards and my foot couldn't get out of the ground, so my knee just got bent sideways," Roethlisberger told reporters Sunday.
The Steelers' victory also cost them defensive end Nick Eason, who left the game with a sprained medial collateral ligament in his left knee. His status is uncertain.
Roethlisberger was 20-for-33 passing for 246 yards against Buffalo.