MEMBER WAS STEPPING OUT OF MANTRIP TO THROW SWITCH AT NO.5 HEAD WHEN HE SLIPPED & FELL TWISTING HIS LT. KNEE. EE CONTINUED TO WORK HE HAD SURGERY ON KNEE 11/22/02 ON HIS SCHEDULED DAYS OFF. HE RETURNED TO WORK ON HIS NEXT SCHEDULED SHIFT. I WAS INFORMED ON 11/25/02 ABOUT HIS SURGERY.