"You always hate when anyone gets injured, and unfortunately we've dealt with our share of injuries in the last 12 months," coach Brady Hoke said in a statement released by the school. "We will support Jake to make sure he has everything he needs to get through this. I know he will attack his rehabilitation just like he does everything else and will be back when he's ready."
Ryan had 88 tackles last season, including 16 for loss (third in the Big Ten). He recorded 4.5 sacks and four forced fumbles.
If Ryan is unable to return in the fall, rising sophomore Joe Bolden (16 tackles, four for loss) likely would step into his spot.
Michigan began spring practice on Saturday.