Southern California senior point guard Jio 12 season before it started.
Fontan, who led the Trojans in assists and was second in scoring last season, suffered the injury during USC's exhibition tour in Brazil,
"I couldn't feel worse for any player I've coached in my career," Trojans head coach Kevin O'Neill said. "Jio is the heart and soul of our team and had become a high-level player. His loss is a huge blow to our team. Our best thoughts go out to Jio and his family during his recovery."
Fontan sat out the first half of last season after transferring from Fordham. Once eligible, the six-foot guard averaged 10.5 points and 3.9 assists in 24 games -- all starts. He scored a team-high 14 points in a loss to VCU in one of the NCAA's inaugural "First Four" tournament games.
Freshman guard Alexis Moore is expected to take Fontan's spot in the starting lineup.