Channel 11's Alby Oxenreiter has confirmed through James Harrison's agent that the Steelers linebacker underwent knee surgery Wednesday morning.

Harrison's agent, Bill Parise, told Oxenreiter that the surgery was a known possibility all along and did not come as a surprise.

Parise added that the surgery went well and that Harrison has returned to camp.

Harrison has spent all of training camp on the Steelers' Physically Unable to Perform list.

"Minor" is the word Steelers Head Coach Mike Tomlin used to describe Harrison's knee surgery. 

Harrison who has been bothered by inflammation in his left knee since mini-camp in June underwent surgery early Wednesday.  "Don't have details on state of that." Tomlin said following Wednesday's practice at St. Vincent College. 

The big question for the Steelers now is, when will Harrison return to the field? 

"Shouldn't be long, we'll see when we get him back out here and start the process of working him," Tomlin said. "It was a procedure we deemed necessary at this time."  

Could Harrison have undergone the surgery earlier, back in May? 

"No, again we just address issues as they arise," Tomlin said. "We felt like the procedure was necessary at this time so we just had it."

The Steelers open their season Sept. 9 in Denver. Time will tell if Harrison can make it back to play, but he has played through pain before. So if the possibility is there for a return, it would be hard to bet against Harrison, Channel 11's Bill Phillips said.

Last season, Harrison missed four regular-season games due to injury. He was sidelined after breaking his orbital bone -- a facial bone housing the eye.

Meanwhile, Steelers' running back Isaac Redman isn't scheduled for surgery, but he said Wednesday that he will undergo an MRI on his groin, which has bothered him since the team's night practice at Latrobe Memorial Stadium.

Redman practiced Wednesday at St. Vincent College in Latrobe.

"He shouldn't be talking to you about MRIs." Tomlin told reports following Wednesday afternoon's workout.