Zobrist, who missed four games with the injury, tried to play through it on Friday but went 0-for-4 in the A's 11-inning, 5–4 loss to the Houston Astros in Oakland.
Over the first 14 games of the season, Zobrist was hitting .240 with one home run, eight RBI and a .704 OPS.
"I wasn't getting out of the box well at all," said Zobrist, batting .240 in 14 games. "And frankly, the worst thing out of it was just trying to swing. When I swung right-handed, specifically, it put a lot of pressure on that front knee, the left knee.
"I just didn't feel like I could be the player that this team needs me to be in the condition that I was trying to play in. So gotta get it cleaned up and get back out here as soon as possible."
Eric Sogard is expected to take over everyday second-base duties for the A's. Zobrist spent five games each at second base and left field before he was shut down.
- Mike Fiammetta