WAS PARKING MY TRAILER AND HAD UNHOOKED IT GO IN TO MOVE IT FORWARD SO I COULD PUT MY TRAILER LOCK ON LEFT THE DOOR OPEN LIKE I HAVE DONE COUNTLESS TIMES PUT THE TRUCK IN PARK AND GOT OUT STARTED TO WALK BACK WHEN THE ENGINE ACCELERATED AND THE TRUCK STARTED TO MOVE BACKWARDS TURNED TO JUMP IN TO HIT THE BREAK WHEN THE DOOR KNOCKED ME DOWN THE FRONT TIRE HIT MY KNEE AND LEG AND THE DOOR CAUGHT A POST RIPPING IT FORWARD