EE WAS STEPPING DOWN OFF OF THE EUCLID DUMP TRUCK AFTER CHECKING THE ANTI FREEZE LEVEL IN THE ENGINE. HE STEPPED ONTO THE BUMPER AND THEN ONTO THE STEP AND LOST HIS FOOTING AND FELL ONTO THE G ROUND. HE STATED THAT HE WAS HAVING PROBLEMS WITH HIS KNEE AND IT WAS POSSIBLE HIS KNEE GAVE OUT.