WHILE CHANGING A TAKE-UP CABLE ON THE 11 BELT TAKE-UP, THE EMPLOYEE SLIPPED AND FELL ON HIS KNEES. EMPLOYEE VISITED MED WORKS AND WAS RELEASED TO FULL DUTY ON 5-7-01. EMPLOYEE CONTINUED TO HAV E DISCOMFORT, RETURNED TO MED WORKS AND AN MRI WAS SCHEDULED. THE MRI REVEALED A TORN CARTILAGE WHICH WILL REQUIRE ORTHOSCOPIC CORRECTION (5-25-01) AND LIGHT DUTY(5-29-01).