The team said an MRI taken Saturday revealed the torn ACL sustained on Tuesday. The fifth-round pick missed his senior season at Florida after tearing the ACL in the same knee almost exactly a year ago.
"He's a great kid and his leg had been doing so well," coach Andy Reid said.
Myers missed his senior season at Utah State after having surgery for turf toe. He signed with the New York Jets after the draft, but was released May 29.
Also, receiver DeSean Jackson hyperextended his knee during Saturday's practice. Reid said the injury was not serious.
Ingram was impressive in offseason workouts and the Eagles had high expectations for him.
"He was doing some good things," Reid said. "He was working his way in. The other guys just have to step up, that's all."
Ingram's injury is the latest setback for a team that reached the NFC championship game last year. Starting middle linebacker Stewart Bradley tore his ACL last Sunday, and right tackle Shawn Andrews still hasn't practiced because of a back injury.