USC opens spring football Tuesday with a rash of injuries that could hinder what the coaching staff is hoping to accomplish, coach Lane Kiffin said Monday, according to an ESPN.com report. The Trojans already had a diminished roster due to NCAA sanctions and Kiffin said 20 players have yet to be cleared by doctors for full contact. "It was just a very unusual amount of offseason surgeries and injuries, unfortunately," Kiffin said.