fracture, breaking of a bone. A simple fracture is one in which there is no contact of the broken bone with the outer air, i.e., the overlying tissues are intact. In a comminuted fracture the bone is splintered. In greenstick fracture (common in children) one side of the bone is fractured and the other side bent. In multiple fracture there is more than one break. A compound fracture is one in which the broken bone is in contact with the air because there is a wound through the skin; the bone may project through the wound. The bones of older people are especially liable to fracture, although no age is exempt. Fractures are caused most often by injury, although certain pathological conditions may predispose a bone to fracture. Osteoporosis, the leaching of calcium from the bone, can cause spontaneous fractures, as can malnutrition and cancer. A person with a fracture should not be moved unless the broken bone has been splinted or otherwise immobilized (see first aid). Proper setting of bones and the application of a cast should be performed by a doctor. X rays aid in the repositioning of the bone as well as in determining the state of healing. Surgery that involves implanting metal pins or screws to join broken bones may be necessary; in certain cases traction devices are used to align bone fragments. Skull and jaw fractures require special treatment.