EMPLOYEE WAS USING 12 LB HAMMER TO DRIVE STEEL WEDGES BEHIND LIP OF GRIZZLY WHEN HAMMER GLANCED OFF HITTING HIS LEFT LOWER LEG. SOME IMMEDIATE SWELLING AND REDNESS DID OCCUR, BUT MEDICAL CARE WAS NOT DEEMED NECESSARY. THERE WAS NO MAJOR PROBLEM UNTIL WEDNESDAY APRIL 16, WHEN SWELLING RE-OCCURRED AND SEVERE DISCOLORATION STARTED.