Steelers QB Ben Roethlisberger escaped a collapsing pocket to his right, as Gilbert battled with Broncos LB Von Miller. As Roethlisberger was falling to the ground, he released the ball, but Broncos DE Derek Wolfe was blocked down into Gilbert's leg, and he fell down.
The Steelers trail the Broncos 7-3 with under three minutes remaining in the second quarter.
Rookie Mike Adams has replaced Gilbert on the right side, and has already drawn a penalty. Gilbert's injury leaves no tackles left with regular season game experience. Behind Adams on the depth chart would probably be rookie Kelvin Beachum.
The Steelers offensive line hasn't had a good opening half, particularly in the running game Steelers offensive coordinator Todd Haley clearly wanted to establish early. The offense has moved slowly, surrendering penetration frequently, and losing the battle for the line of scrimmage.