Dixon started the Steelers' first two games in place of the suspended Ben Roethlisberger. He was injured on a run during the first quarter of a 19-11 victory at Tennessee on Sept. 19. Charlie Batch took over and Dixon had surgery later in the week.
The move Saturday allows the Steelers to activate defensive lineman Steve McLendon for Sunday's game against Baltimore.
With Dixon unable to play until next season, the Steelers apparently will keep Batch and Byron Leftwich as backups when Roethlisberger's suspension ends Monday.