Gasol, who missed 26 games earlier this season with a stress fracture in his foot, missed the Bucks' past three games because of this injury. He joins teammates Nikola Mirotic and Malcolm Brogdon among those likely out for the remainder of the regular season.
The 38-year-old Gasol joined Milwaukee after reaching a buyout agreement with the San Antonio Spurs in February, but he has played in only three games for the Bucks. Milwaukee viewed Gasol as a veteran with playoff success who could help prepare the team for the rigors of the postseason.
Gasol is averaging a career-low 3.9 points and 4.6 rebounds in 30 games this season.