EMPLOYEE WAS BACKING OFF A PORTABLE WORK PLATFORM USED TO WORK ON LHD'S IN MAIN SHOP. HIS FOOT CAUGHT ON THE BOTTOM STEP CAUSING HIM TO FALL FROM THE BOTTOM STEP TO SHOP FLOOR. HE PUT HIS RT H AND & ARM OUT TO BREAK FALL & JAMMED RT SHOULDER. EMPLOYEE HAD SURGERY ON 2/3/03.