Coach Darrell Hazell says Robinson will have surgery on Oct. 28. He was injured an Oct. 4 victory at Illinois.
Robinson, who began his Purdue career as a quarterback before making the switch to defense, had 42 tackles in six games this season.
Purdue (3-5, 1-3 Big Ten) have a bye week and will return to action on Nov. 1 at No. 16 Nebraska.