Allen has been dealing with a knee injury that he sustained during the first game of the season.
The Steelers will move forward with some combination of William Gay, Antwon Blake, Ross Cockrell and Brandon Boykin. They could also promoted Doran Grant from their practice squad in the coming weeks if needed.
Allen, 26, is a former fourth-round pick of the Steelers back in 2011. He’s currently in the second year of his five-year, $26 million contract that included $6.75 million guaranteed and stands to make a base salary of $2.631 million for the 2015 season.
This season, Allen was limited to appearing in just a single game and recording six tackles for the Steelers.