Bradley was hurt early in the second quarter Sunday night. He stayed down on the ground at the end of a play when another defender hit Dallas quarterback Jon Kitna on a third-down incompletion.
Bradley was holding his helmet in his left hand when he left the field through a tunnel that leads to an X-ray room. After he was evaluated, it was announced that Bradley wouldn't return.
After missing last season with a torn ACL, Bradley sustained a concussion in the season opener. He returned to play more in that game before sitting out the second game.