Soliai left Sunday's 20-13 win over Carolina with the injury and again slowly limped off the field after returning to the game.
Soliai had 22 tackles and one fumble recovery in 14 games this season. He signed a five-year contract with Atlanta as a free agent before the 2014 season following seven years with the Dolphins.
The Falcons promoted tight end D.J. Tialavea to the 53-man roster for this week's final regular-season game against New Orleans. Tialavea has been on Atlanta's practice squad since Week 12. He was a member of Buffalo's practice squad in 2014 but has not appeared in a NFL game.
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