"It's going to be hard to get the proper rest and come back," he said, when asked about his chances of pitching again this season.
Pettibone said it could have been worse.
"It's nothing serious," he said. "It's just going to take time. They gave me six days at first, and it just wasn't enough. It's mild inflammation, but it never really went away."
Todd Zolecki is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.