"That's the good news," Cowboys owner Jerry Jones said.
Colombo had at least some of the damage "probably for the last couple of years," Jones said. They became enough of a problem Sunday that he left the practice field on a cart. He flew back to Dallas for the arthroscopic procedure.
"One (particle) really was limiting him," Jones said. "I don't have exactly how long he'll be down, but those things have a time of 10 days to two weeks."
That timetable means Colombo will miss at least two preseason games. He could be back for the preseason finale Sept. 2, a game in which the starters traditionally play only a few snaps, if at all. He could be held out until the opener Sept. 12 at Washington.
"I don't have any doubt he'll be back for the opener based on the information I just got from the MRI and what we saw the problem was," Jones said.
Colombo missed the final seven games of the regular season last year, but that was because of his left leg, a broken fibula and high ankle sprain. His career was nearly derailed by a left knee injury as a rookie in 2002 with Chicago; he didn't become a regular again until 2006 with Dallas.
Doug Free filled in for Colombo last season, but now he's the starter at left tackle. Youngsters Robert Brewster and Sam Young are the likely fill-ins Saturday night against San Diego. Offseason acquisition Alex Barron would be another option, but he's sidelined with a sprained ankle.
"This will give Brewster a good chance, Young a good chance. All that is good," Jones said. "Of course, Barron has had right tackle experience. We won't mess with Free. He's playing too well at left tackle. That's where we want him."
Dallas took Brewster 75th overall last year, but an injury sidelined him all season. He was playing behind Young, a fourth-round pick this season, but moved ahead of Young on Monday.
"It's great for training camp," offensive line coach Hudson Houck said. "Now we get to throw some other guys in there."
Brewster is likely to start against San Diego. It'll be his first game since 2008, his senior year at Ball State. As a backup the first two games, he's gone from "a lot of mistakes in the first ballgame," said coach Wade Phillips, to "I think he had one mental error in the second game."
"I just have to keep working on my technique and work on not getting on my heels, and work to adjust to the speed of the game," Brewster said. "I'm just glad to be able to get on the field and be playing."
Barron could be working with the first team by next week. Phillips listed him as doubtful to play Saturday night, but probable for the following game.
"In the regular season, he could probably play and would play," Phillips said.
Colombo was beaten for two sacks in the last preseason game, part of a rocky start so far for the Dallas offense. It's possible the knee problem already was flaring up.
On Sunday, it wasn't even Colombo who turned it into a big issue. Center Andre Gurode tipped off the staff that something was wrong.
"He doesn't complain about anything," Houck said. "I know in the morning practice he had some (pain) and he tried to work it out. I think he probably had those in the past where he's felt it and then he's kind of worked it out. He just couldn't work this one out."
The scare with Colombo is a reminder that Dallas has four linemen over age 30. If any are lost for a significant time, and especially if two go down, it could jeopardize the team's hopes of reaching the Super Bowl that's being held in their stadium.
Jones insists he's not only OK with it -- he likes it.
"When you look at a team that's got a veteran offensive line, that's an asset," he said. "I'm interested in this year. We've got our focus right now on this year."
Dallas Cowboys right tackle Marc Colombo had five loose particles removed from his right knee Monday, a clean-up job that could sideline him for the rest of the preseason but should have him feeling better than ever when the regular season begins.
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