Abdominal Injuries: General or unspecified injuries involving organs in the abdominal cavity.Wounds, Nonpenetrating: Injuries caused by impact with a blunt object where there is no penetration of the skin.Multiple Trauma: Multiple physical insults or injuries occurring simultaneously.Injury Severity Score: An anatomic severity scale based on the Abbreviated Injury Scale (AIS) and developed specifically to score multiple traumatic injuries. It has been used as a predictor of mortality.Accidents, Traffic: Accidents on streets, roads, and highways involving drivers, passengers, pedestrians, or vehicles. Traffic accidents refer to AUTOMOBILES (passenger cars, buses, and trucks), BICYCLING, and MOTORCYCLES but not OFF-ROAD MOTOR VEHICLES; RAILROADS nor snowmobiles.Seat Belts: Restraining belts fastened to the frame of automobiles, aircraft, or other vehicles, and strapped around the person occupying the seat in the car or plane, intended to prevent the person from being thrown forward or out of the vehicle in case of sudden deceleration.Thoracic Injuries: General or unspecified injuries to the chest area.Wounds, Penetrating: Wounds caused by objects penetrating the skin.Child Restraint Systems: Devices used to protect and restrain infant and child automotive passengers.Abbreviated Injury Scale: Classification system for assessing impact injury severity developed and published by the American Association for Automotive Medicine. It is the system of choice for coding single injuries and is the foundation for methods assessing multiple injuries or for assessing cumulative effects of more than one injury. These include Maximum AIS (MAIS), Injury Severity Score (ISS), and Probability of Death Score (PODS).Wounds and Injuries: Damage inflicted on the body as the direct or indirect result of an external force, with or without disruption of structural continuity.Laparotomy: Incision into the side of the abdomen between the ribs and pelvis.Wounds, Gunshot: Disruption of structural continuity of the body as a result of the discharge of firearms.Wounds, Stab: Penetrating wounds caused by a pointed object.Brain Injuries: Acute and chronic (see also BRAIN INJURIES, CHRONIC) injuries to the brain, including the cerebral hemispheres, CEREBELLUM, and BRAIN STEM. Clinical manifestations depend on the nature of injury. Diffuse trauma to the brain is frequently associated with DIFFUSE AXONAL INJURY or COMA, POST-TRAUMATIC. Localized injuries may be associated with NEUROBEHAVIORAL MANIFESTATIONS; HEMIPARESIS, or other focal neurologic deficits.Athletic Injuries: Injuries incurred during participation in competitive or non-competitive sports.Spinal Cord Injuries: Penetrating and non-penetrating injuries to the spinal cord resulting from traumatic external forces (e.g., WOUNDS, GUNSHOT; WHIPLASH INJURIES; etc.).Reperfusion Injury: Adverse functional, metabolic, or structural changes in ischemic tissues resulting from the restoration of blood flow to the tissue (REPERFUSION), including swelling; HEMORRHAGE; NECROSIS; and damage from FREE RADICALS. The most common instance is MYOCARDIAL REPERFUSION INJURY.Retrospective Studies: Studies used to test etiologic hypotheses in which inferences about an exposure to putative causal factors are derived from data relating to characteristics of persons under study or to events or experiences in their past. The essential feature is that some of the persons under study have the disease or outcome of interest and their characteristics are compared with those of unaffected persons.