All three -- including Pouncey, linebacker Larry Foote and running back LaRod Stephens-Howling -- are facing season-ending surgery.
Pouncey sustained two ligament tears in the right knee during Sunday's season-opening loss to the Tennessee Titans.
Stephens-Howling also suffered a torn knee ligament while Foote was hit with a ruptured biceps in the same game.
Meanwhile, the Steelers inked former Tennessee center Fernando Velasco to replace Pouncey, while running back Jonathan Dwyer was signed to take Stephens-Howling's roster spot.
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