The injury occurred during the first half of No. 3 Purdue's 59-58 win at Minnesota on Wednesday. Purdue made the announcement Thursday after Hummel underwent an MRI examination.
Losing Hummel could deal a blow to No. 3 Purdue's chances at winning the Big Ten title or gaining a No. 1 seed in the NCAA tournament. The junior averages 15.7 points and 6.9 rebounds per game.
Hummel missed several games last season with a back injury, and the Boilermakers struggled without him.
Purdue hosts No. 14 Michigan State on Sunday.