THREE EMPLOYEES WERE CHANGING LOWER CHECK PLATES ON JAW CRUSHER. ONE WAS USING A PRY BAR TO LINE UP HOLES FOR BOLTS. THE BAR SLIPPED & HIS LEFT KNEE POPPED. PRY BAR DID NOT HIT KNEE. EMPLOYEE TOOK IT EASY OVER THE WEEKEND, BUT ON MONDAY HIS KNEE STARTED SWELLING. HE WAS TAKEN TO THE DOCTOR. AN MRI CONFIRMED TORN MEDIAL MENISCUS AND OUTPATIENT SURGERY SCHEDULED.