247sports first reported the injury.
Blacklock was the co-Big 12 Defensive Freshman of the Year and a FWAA Freshman All-American last season, after finishing with 27 tackles, including 6.5 for loss, and two sacks.
He was expected to be a big piece on a stalwart TCU defensive line that included preseason Big 12 Defensive Player of the Year, Ben Banogu. With Blacklock out, the Horned Frogs are expected to turn to redshirt freshman Terrell Cooper.
TCU opens the season Sept. 1 against SWAC team Southern University.