EE WAS STANDING ON TOP STEP OF A 3-STEP WHEELED WORK PLATFORM WORKING ON A LHD. AS HE LEANED OVER ONTO LHD TIRE, IT REMOVED ENOUGH WEIGHT TO RELEASE THE WHEELS CAUSING THE PLATFORM TO MOVE AWA Y SLIGHTLY. THIS CAUSED THE EE TO LOSE HIS BALANCE AND FALL 2' TO THE FLOOR LANDING ON HIS LEFT HAND. POSSIBLE FRACTURE - CASTED AND RELEASED TO RESTRICTED DUTY NOT LIFTING OVER 10 LBS.