EE WAS WORKING ON 777 HAUL TRUCK. HE WAS GOING UNDER TO CHECK ON A BROKEN COOLING LINE. HE STEPPED ON THE STEAMER LINE THAT ANOTHER EE WAS USING AT THE TIME. THE LINE ROLLED CAUSING HIM TO TWI ST HIS KNEE. THE RESULT WAS A MEDIAL MENISCAL TEAR. FIRST DAY MISSED WAS 07-11-2002. NOT REPORTABLE UNTIL THEN.