WHILE REPLAICNG A CUTTING EDGE PLATE ON THE UNDERSIDE OF A VOLVO L70D FRONT END LOADER BUCKET, EE ON ONE KNEE BENDING FOREARD AND SUPPORTING THE CUT EDGE PLATE WITH HIS RIGHT HAND. HE TWISTED HIS UPPER BODY TO THE RIGHT TO REACH FOR AN INSTALLATION BOLT WITH HIS LEFT HAND, CAUSING A SHARP PAIN TO HIS LOWER BACK. EE WAS PLACED ON LIGHT DUTY BY DR 3-2-04.