Coach Tom Allen says the senior will undergo surgery.
Cronk started all 40 games since he arrived on campus four years ago but was injured early in Saturday's 38-3 victory over Connecticut when another player appeared to roll up on his leg, pinning it underneath Cronk's body.
Trainers placed an air cast around the senior's lower leg and teammates wished Cronk well as the 6-foot-5, 325-pound offensive lineman was lifted onto a golf cart.
Matthew Bedford, a true freshman, could replace Cronk in the lineup when the Hoosiers (3-1, 0-1 Big Ten) visit No. 25 Michigan State (3-1, 1-0).