A source said Reagor is expected to undergo surgery and will be placed on injured reserve.
Reagor was injured on a play across the middle in the first half of Sunday's loss to the Los Angeles Rams. He stayed in the game and finished with four catches for 41 yards.
There is a chance the Eagles could hold him out until after their Week 9 bye as a precaution. For context, New Orleans Saints quarterback Drew Brees missed five games with a similar injury last season.
Reagor has a recent track record of recovering quickly, however, returning from a slight shoulder tear in two weeks earlier this month in what was originally supposed to be a monthlong absence.
Reagor, the team's first-round pick, has five catches on eight targets for 96 yards this season.