By Chris Emma–

BOURBONNAIS, Ill. (CBS) — Two days after being placed on the physically-unable-to-perform list, Bears linebacker Pernell underwent arthroscopic surgery on his right knee Friday morning, coach John Fox said. The surgery was termed a “cleanup” by Fox, and it’s unclear how long McPhee will be out.

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Fox also termed the ailment as an “irregularity” in McPhee’s left knee, which was discovered in his entry physical Wednesday upon reporting for camp at Olivet Nazarene. McPhee has missed a combined nine games in his first two seasons with the Bears while managing troubles his left knee. He also began last training camp on the PUP list, where he remained to open the regular season. McPhee would return after missing seven games.

A year ago, cornerback Kyle Fuller underwent a knee scope that kept him out for the entirety of the 2016 season. Fox explained that McPhee’s procedure was different.

“It was literally a cleanup and something they were glad they went in,” Fox said.

McPhee’s continued knee problems are a great source of concern for the Bears. Knee injuries have now slowed him in each of his three seasons in Chicago after the team gave him a five-year deal worth just shy of $16 million guaranteed and up to about $39 million. He had 16 tackles and four sacks in nine games last season.

During the offseason, McPhee spoke with optimism about playing in good condition. His left knee had finally healed and he had dropped weight to become lighter on his feet.

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McPhee can’t practice with the Bears until he’s removed from the PUP list. He may continue to join team meetings and receive medical treatment.

On Thursday afternoon, general manager Ryan Pace shed light on McPhee’s situation in an interview on 670 The Score.

“We did our physicals yesterday, we had the conditioning tests yesterday,” Pace said. “You know, it’s inevitable. It’s part of the game. These guys come in, do their physicals and sometimes there’s things that surprise you. And being honest with you, Pernell’s had a good summer, a good offseason. His weight is at a good spot right now, and he came in and his knee was a little aggravated in the physicals that we had yesterday. And honestly, it’s the other knee.

“So we’re kind of working through that right now, trying to get that to calm down right now. And you know, PUP is a tool the NFL gives us. We should use it to our advantage, and I feel like we’re doing that, just being thorough. What exactly do we have here and what’s the best course of action?”

Extra points: The Bears welcomed back defensive lineman Eddie Goldman and defensive back Deon Bush on Friday after both were pulled from conditioning tests Wednesday. Goldman, who has dropped nearly 20 pounds entering camp, was dealing with dehydration, according to Fox. … Cornerback Marcus Cooper was present Friday after dealing with a hamstring injury … The Bears worked Friday in a closed setting and conducted a light walk-through, this in advance of their first practice in full pads on Saturday. They will work three days before an off day Tuesday.

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Chris Emma covers the Bears, Chicago’s sports scene and more for Follow him on Twitter @CEmma670 and like his Facebook page.