PITTSBURGH — Pittsburgh Steelers linebacker Joey Porter is expected to have arthroscopic knee surgery as early as today, less than a year after having loose cartilage removed from his left knee.

The Steelers did not say which knee requires surgery.

Porter took part in the Steelers' minicamp May 13-15, but has missed the voluntary coaching sessions held since then. Porter, a three-time Pro Bowl linebacker, worked out Tuesday on his own at the team's practice complex.

Porter missed most of training camp and the four exhibition games last summer after needing knee surgery — a problem aggravated when he jumped in the air to celebrate winning a training camp blocking battle. He returned to play in the Super Bowl champions' 16 regular season games and four playoff games.