The mystery of Brian Urlacher's prolonged absence from training camp was solved Tuesday.

Urlacher had early-morning arthroscopic surgery on his left knee to relieve swelling after missing two weeks of camp for what the Bears and their veteran middle linebacker said was personal reasons. Urlacher reiterated his absence was to tend to a personal matter when asked Monday.

"I am just going to keep resting right now," Urlacher told FOX Chicago on Monday. "I have never had a scope. I don't know how that stuff works."

Urlacher had the surgery Tuesday according to the Chicago Tribune. He's hopeful of being able to play in 26 days when the Bears open the regular season against the Colts at Soldier Field in Chicago.

"Even if I just practice the week before," Urlacher told FOX, "I'll be in good enough shape to make it through those games. But I've got to be out there when the games count."

Nick Roach has been playing inside linebacker in Urlacher's absence, which began August 1. He injured his left knee on Jan. 1 at Minneapolis, when he sprained his left MCL and PCL.

He didn't participate in offseason workouts, but coach Lovie Smith said the cautious approach was taken because of Urlacher's age (34) and the fact that he's worked in the same role in the same defense since 2004 and had little to gain by getting on the field in May and June.

Urlacher is in the final season of a five-year, $40.6 million deal he signed in 2008. General manager Phil Emery has been noncommittal when pressed on whether the team would make a push to keep Urlacher before he can test the open market.

Any deal now is likely dependent upon how Urlacher performs in the early stages of this season.