Pittsburgh Steelers safety Troy Polamalu practiced in a limited role for the first time in seven weeks, although it seems unlikely he will play Sunday in Miami. Polamalu has missed 10 full games and most of two others with a pair of left knee injuries. He hasn't played since Nov. 15 against Cincinnati because of a sprained posterior cruciate ligament. Polamalu called his current layoff "frustrating," but said it would be difficult to play after only a few days of practice following such a long time off. According to Polamalu, his knee is still healing. He did not run at close to full speed and he appeared tentative doing some work.