It results from this that a great many grooves exist without any solution of continuity of the bone. Undoubtedly we may see rather shallow grooves of the diaphyses which consist of abrasions without fissures, but this is exceptional, and usually a fracture by contact accompanies the grooving of the bone. As we have before pointed out, it changes many of the splinters into secondary projectiles, which increase in number, and by their comminution extend the field of damage. In such a case there is no change of shape of the bullet, the reduction of the splinters into fragments is shown by their transformation into dust, which is gently projected into the soft parts. They are found lying around the aperture of entry into the bone.
Most free splinters come from the bony aperture of exit.
With them are sometimes found splinters that have been set free from the lateral walls where large splinters have been subdivided. These free splinters, therefore, cannot exist in contact fractures or in incomplete perforations . This is an important dictum which surgeons should bear in mind. The higher the velocity of the projectile causing them, the shorter they are. We must not forget that this musculo-cutaneous canal extends from the aperture of exit in the bone to the aperture of exit in the skin.