Butler, who recently had been demoted to a backup role, suffered the injury in Thursday's preseason finale against the Minnesota Vikings.
Texans coach Gary Kubiak confirmed the injury after the game but did not say whether Houston plans to put Butler on injured reserve. Butler also missed 14 games last season with a torn left triceps.
"It's unfortunate -- a tough, tough deal," Kubiak told reporters. "He comes back from the other injury, battles, does a heck of a job and handles himself like a big-time pro. You hurt for guys that work their tail off."
A seven-year veteran, Butler lost the starting right tackle job to rookie Derek Newton earlier this week.