EMPLOYEE WAS MOVING THE CUTTING EDGE FROM LOADER TO KEEP FROM BLOCKING THE DRIVEWAY FOR INCOMING TRUCKS. AFTER HE MOVED THE CUTTING EDGE (WEIGHT APPROX. 80 LBS) HE FELT DISCOMFORT IN HIS LOWER BACK. HE WORKED ABOUT TWO HOURS IN LOADER. WHEN HE STEPPED DOWN FROM LOADER, HE HAD SEVER PAIN IN HIS LOWER BACK & COULD NOT STAND UP RIGHT OR WALK WITHOUT A LIMP.