EE using 10lb sledge hammer while changing the teeth on a dragline bucket. The 1st 3 teeth came off. The 4th tooth was stuck, so he tapped harder. He felt something hit his leg, but did not hurt. Hit tooth again. Felt something warm on leg, it was blood on pant leg at knee. Taken to ER and X-rays done, showed piece of metal in leg. Unsuccessful to remove it, Dr put 3 stitches.