Berkman had already missed action when he was on the shelf April 19-May 12 with a strained left calf.
The six-time all-star landed on the 15-day disabled list again after hurting his right knee Saturday while stretching at first base to catch a throw from shortstop Rafael Furcal on a routine ground ball.
The team made an initial diagnosis of a strained right knee.
Berkman was batting .333 with five doubles, a homer and four RBI over just 13 games this season.
The Cardinals called up first baseman Matt Adams from Class AAA Memphis to take his spot in the roster.