What would have been one of the best (if not the best) stories to come out of USC's spring camp has been cut unfortunately short, as rising sophomore running back Tre Madden tore a knee ligament in Thursday's practice.

The Trojans confirmed the injury in a tweet from the official USC athletics account, indicating that Madden will have surgery and is out for the year:

Madden had been one of the highlights of the Trojans' spring, having moved from linebacker to shore up USC's depth chart in the backfield and proven to be a dynamic, physical runner.

"He's a running back," head coach Lane Kiffin said after an early practice. "Some guys just do things naturally, and he's one of those guys. For him to make the switch and come over to offense and be functional is saying a lot."

Sadly for Madden, that all ended near the conclusion of practice Thursday, when he made a cut and injured his right knee. Kiffin immediately expressed "concern" that the injury could be a major one.

As you might expect -- given that the move was made to boost the team's tailback depth in the first place -- the injury leaves the Trojans without their typical stable of high-quality options behind Matt Barkley. CBSSports.com's Bruce Feldman's take:

Senior Curtis McNeal -- a 1,000-yard rusher in 2011 -- is the obvious No. 1 tailback, with rising sophomore D.J. Morgan likely the No. 2 option. But Morgan averaged less than four yards per his 42 carries last year, and no other Trojan runner took more than 19 handoffs.

As long as McNeal stays healthy and Morgan improves, Madden may not be missed--but if they don't, Thursday's news could prove even worse than it appears at first.

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