EMPLOYEE STATED THAT HE STEPPED OVER A BEAM APPROXIMATELY 4"" HIGH FROM WALKING LEVEL AND AS HE PUT HIS WT ON HIS RT FOOT, HIS ANKLE TURNED CAUSING HIM TO LOSE HIS BALANCE AND FALL ON CONCRETE FLOOR. EE STATED HIS ANKLE HURT. AT FIRST EE THOUGHT IS WAS AN ANKLE SPRAIN. EE RETURNED TO WK ON 2/15/01 BUT HAD TO RETURN TO DR ON 2/16/01.