The injury was suffered in the first half of Pittsburgh's 16-14 victory over the Philadelphia Eagles last Sunday. It was an aggravation of a right-calf injury that kept him out of Pittsburgh's Week 2 and Week 3 games against the New York Jets and Oakland Raiders.
While Polamalu was out against the Titans, Steelers head coach Mike Tomlin stated in a press conference on Monday that Polamalu's injury "will be evaluated after Tennessee" (per the Pittsburgh Post-Gazette).
However when asked about Polamalu's injury in a chat on ESPN.com, ESPN's AFC North blogger Jamison Hensley answered:
The Steelers classify it as a week-to-week proposition with Polamalu. I can't see him coming back for another couple of weeks. Can the Steelers make the playoffs without him? Sure, but it will be definitely tougher. If I had to point to one player that means the most to that defense, it's Polamalu.
Gerry Dulac of the Sporting News is reporting that Polamalu could miss three games in total due to his injury.
The Steelers started Will Allen at strong safety over Ryan Mundy, who had started in place of Polamalu in the previous two games Polamalu had missed this season.
Going back to 2009, Polamalu has missed 16 games, counting this week's Thursday night game against Tennessee, due to various injuries. In those previous 15 games, the Steelers went 7-8, while going 28-9 in the 37 games he did play.