EMPLOYEE WAS IN THE PROCESS OF HAVING HIS TRUCK LOADED WITH REFUSE. WHILE BEING LOADED HE STEPPED UP APPROX 18 INCHES ON THE FRONT OF THE CAB TO VIEW THE LOADING. WHEN HE STEPPED DOWN, HE TWIS TED AND FELT A SHARP PAIN IN HIS LOWER BACK. THE FOLLOWING DAY HE WAS TAKEN TO FAMILY CLINIC AND DIAGNOSED WITH STRAIN OF THE LUMBAR REGION. PHYSICAL THERAPY.