The team filled his spot on the roster Sunday by promoting catcher Steven Lerud from Triple-A Lehigh Valley.
Kratz was hurt while running to first in the ninth inning in Saturday's 4-3 loss to the Brewers. Manage Charlie Manuel said "Kratz heard his knee pop. It's not good."
Kratz was hitting .229 with eight home runs and 22 RBIs in 43 games.
