Gattis, 27, has hit .290/.342/.558 (146 OPS+) with 16 home runs in 243 plate appearances this season. He has taken over as the team's everyday catcher in the wake of Brian McCann's free agent defection.
With Gattis sidelined, the Braves will rely on veteran Gerald Laird and youngster Christian Betancourt behind the plate. Ryan Doumit can also catch if need be.
Gattis was a legitimate All-Star Game and Home Run Derby candidate. The back injury all but guarantees he will not be in Minnesota for the Midsummer Classic.