The injury bug has been nipping at the USC Trojans all spring, as wide receivers and tight ends have missed time with nagging injuries. But during Thursday's practice it took a big bite out of the Trojans' running back depth, as tailback Tre Madden tore a ligament in his knee and will be out for the 2012 season, according to a school news release. It happened on a run in which Madden was untouched and but went to the ground after attempting to make a cut in the open field.