Pham will be with the team for Friday night’s game at the Atlanta Braves.
Piscotty suffered the injury running to first base on his grounder in the second inning of Thursday night’s 5-4 loss to Milwaukee. Jose Martinez replaced Piscotty in right field.
Cardinals center fielder Dexter Fowler left the game with a strained right shoulder, leaving the team in need of outfield depth.
Pham appeared in 78 games with St. Louis last season and was hitting .283 with four homers and 19 RBIs for Memphis.