EE's were replacing broken links on the Dozer. EE was using a sledgehammer to drive the pin into the link. EE swung,immediately felt like he had been hit by a rock in the scrotum. EE observed blood,felt sore and went home. On 3/24 ee felt like something was in the scrotum area,co,sent ee for medical attention.EE had surgery on 3/31/15 to remove the metal splinter from his scrotum.