TRUCK DRIVER WAS DESCENDING THE FRONT LADDER OF THE TRUCK. HIS FOOT SLIPPED OR HE MIS-JUDGED THE STEP AND FELL ABOUT 4 FEET TO THE GROUND, LANDING ON HIS FEET. WORKED THE REMAINING SHIFT BUT H AD TO BE SEEN AT DOCTOR THE NEXT DAY BECAUSE OF PAIN & STIFFNESS IN THE LEFT KNEE. LOST TIME. *NOTE* THIS OPERATOR WAS FACING THE LADDER PROPERLY WHEN THIS OCCURRED.*