He is expected to miss six weeks with the injury but the timetable won't be known until after Wednesday's surgery is complete.
Brees suffered the injury in the second quarter of Sunday's game against the Los Angeles Rams and he wasn't able to return.
The Fox broadcast showed him unable to pick up a football in the second half:
This type of extended injury is a new problem for Brees, who hasn't missed more than one game in a season since 2003. The quarterback only missed three games in the first 13 years he spent in New Orleans, two of them for rest in Week 17 before the playoffs.
Now he will likely be out at least through the bye in Week 9, hurting the Saints' chances of reaching the playoffs one year after reaching the NFC Championship Game.
Teddy Bridgewater took over for Brees in Week 2 and would presumably handle the starting role until the starter is able to return. Taysom Hill could also play the position on a part-time basis.
While Bridgewater does have 29 games of starting experience in his career, his presence is a major drop-off from the future Hall-of-Fame quarterback.