If the bone breaks in such a way that bone fragments stick out through the skin or a wound penetrates down to the broken bone, the fracture is called an "open" or compound fracture. For example, when a pedestrian is struck by the bumper of a moving car, the broken shinbone may protrude through a tear in the skin and other soft tissues.
Because open fractures often involve more damage to the surrounding muscles, tendons, and ligaments than closed fractures, they have a higher risk for complications and take a longer time to heal.
This type of fracture is particularly serious because once the skin is broken, infection in both the wound and the bone can occur.