Proctor waved to the crowd as he was taken into the locker room, wearing what appeared to be an air cast on his right leg. He had to be helped onto the cart by medical staff, and his teammates surrounded him in support.
Proctor, who was a game-time decision after injuring his shoulder late in the season opener against Minnesota, was down on the field for several minutes.
An Ohio State spokesperson had no further injury information at the time and said the athletic department won't report it.
No. 3 Ohio State was trailing 21-14 when the injury occurred, and Oregon scored on the following play after Proctor was taken into the tunnel.
Ohio State was allowing 9.3 yards per carry at the time of Proctor's injury, and it had no answer for Ducks running back CJ Verdell, who finished with 161 rushing yards and three touchdowns.