Boxer's fracture is also known as brawler's fracture. It is usually caused by the impact of a clenched fist with a skull or a hard, immovable object, such as a wall or a door. The knuckle of the little finger tends to lead the rest of the knuckles in a hard punch, and the knuckle compresses and snaps the neck of the metacarpal bone. To prevent it in the future it is recommended that you punch with the tightest possible clenched fist.