Manager Rocco Baldelli said an MRI showed it to be a Grade 2 strain, and that while Buxton won't need surgery, he'll likely be on the IL for more than just the 10 days.
The Twins also announced before Friday's game at Detroit that they have selected the contract of outfielder Trevor Larnach from Triple-A St. Paul. ESPN's Kiley McDaniel had Larnach rated as his 37th-best prospect entering the season.
The injury interrupts a stellar start for the 27-year-old Buxton, who is hitting .370 with nine home runs and five stolen bases. Buxton has played more than 100 games in a season just once in his big league career.
To make room for him on the 40-man roster, the Twins designated left-hander Brandon Waddell for assignment.
Information from The Associated Press was used in this report.