An MRI test Monday determined the extent of Bradley's injury.
Bradley was helped off the field after a tackle Sunday night, and said at the time he felt fine.
At training camp on Monday, head coach Andy Reid refused to confirm Bradley's injury. Reid said he was upset with some members of the media for contacting Eagles' players and staff about Bradley's injury, instead of waiting for an official announcement.
Bradley, a third-round pick in 2007, had 151 tackles in his first full season as a starter last year. He's the primary signal caller on a defense that already lost veteran safety Brian Dawkins in free agency.
Also Sunday night, cornerback Ellis Hobbs left with a stinger.
Hobbs, acquired in a trade with New England, is competing for a starting job with Sheldon Brown.
A total of 31,786 fans came out to Lincoln Financial Field to watch the inaugural /*Eagles Flight Night*/.
Information provided by the Associated Press was used in this story.
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