EE WAS OPERATING A SMALL BOBCAT FRONT END LOADER. WHILE DOING SO THE EE WAS HAVING TO FREQUENTLY TWIST HIS TORSO TO LOOK OVER HIS SHOULDER TO SEE WHERE HE WAS GOING AS HE BACKED THE FRONT END LOADER. THIS REPEATED TWISTING AGGREVATED A PREVIOUS SHOULDER INJURY. THE EE REPORTED THE INJURY 12/08/03. HE WAS PLACED ON MODIFIED DUTY ON 12/15/03.