Buxton suffered the injury while trying to steal second base in loss to the Chicago White Sox on Tuesday. He played in Wednesday's series finale against the White Sox, but struck out in each of his four plate appearances.
The move is retroactive to June 25. In a corresponding roster move, Minnesota called up shortstop Danny Santana form Triple-A Rochester.
Santana made Minnesota's Opening Day roster but hit .218 in 49 games this season before being sent back down to the minors.
Buxton is batting .189 with seven hits and 15 strikeouts in 37 at-bats this season.
Buxton, 21, was the top-ranked prospect by MLB.com when he was called up on June 14 after batting .283 with six home runs, 37 RBIs, 20 stolen bases and an .840 OPS in 59 games for Double-A Chattanooga this season.
Minnesota enters this weekend's series against the Milwaukee Brewers with a 39-33 record, 3.5 games behind the Kansas City Royals in the American League Central.
- Scooby Axson