EE WAS UNLOADING BELT STRUCTURE FROM BELT SKID. WHILE RAISING UP; PICKING UP A STAND HE TURNED TO THE LEFT TO PLACE STAND NEXT TO BELT & HIS LEFT KNEE POPPED & GAVE OUT. HE STOOD UP & FLEXED H IS LEG BACK & FORTH. WHEN HE CLIMBED OVER THE BELT HE FELT A SHARP PAIN. THE KNEE BEGAN SWELLING & PAIN WAS FELT WHEN HE WOULD PUT WEIGHT ON IT. HIS KNEE WAS ICED & HE WAS TAKEN TO ER.