THE EMPLOYEE REPORTED WHILE STANDING IN THE CARGO AREA OF A FORD TRACTOR, THE OPERATOR DROVE OVER A ROUGH AREA OF THE ROADWAY. THE EMPLOYEE LOST HIS BALANCE STRIKING THE SIDE OF THE CARGO AREA WITH HIS SELF-RESCUER. CONTUSIONS TO THE UPPER HIPS AND A SPRAINED LOWER BACK RESULTED. THE EE SAW THE COMPANY DOCTOR ON 1-16-02 AND AGAIN ON 2-14-02 AND PLACED ON RESTRICTED DUTY.