In another medical development, left tackle Tra Thomas had arthroscopic surgery on his right knee. He's expected to miss roughly two weeks and won't play in the exhibition game against the Chicago Bears on Aug. 14.
Thomas was signed as insurance because of Marcus McNeill's holdout. Brandyn Dombrowski is working exclusively with the first team and undrafted rookie Nick Richmond has been taking snaps at left tackle on the second team.
McNeill's agent, Alvin Keels, said in an e-mail that there has been "zero movement at this point" with the Chargers. McNeill, wide receiver Vincent Jackson and outside linebacker Shawne Merriman are staying away from camp, unhappy at not being given long-term contracts. McNeill and Jackson could hold out through the season's 10th game. It's not known when Merriman will report.
Chargers general manager A.J. Smith didn't return a call seeking comment.
Butler, who was injured on Tuesday, said his injury was "heartbreaking. I've never dealt with something like this. Right now I'm just trying to make it through."
He was a third-round draft pick out of Washington.
"I'm disappointed for him because he was doing everything we needed him to do in order to be a part of it," coach Norv Turner said. "We went through it last year in so many different spots, and someone else has got to step up."