Blunt force trauma

Definition: Trauma caused to a body part by a blunt instrument or surface through physical impact, injury, or attack.

Significance: By examining the types of injuries incurred by a victim of blunt force trauma, forensic scientists may be able to determine the cause of the accident or crime that resulted in the injuries as well as what type of instrument caused the injuries.

“Blunt force trauma” is a general term that covers trauma to the body from a variety of sources. Blunt force trauma, also known as blunt trauma, results when the body is struck by an object or when the body strikes an object. When a forensic scientist is asked to investigate blunt force trauma, it is usually to determine what instrument or event caused the injuries—for example, to determine whether the injuries resulted from a beating as opposed to a fall. Blunt force trauma to the body is not always life-threatening (unless organs or blood vessels rupture), but blunt force trauma to the head may cause death. Injuries that indicate blunt force trauma include lacerated blood vessels (including major vessels such as the aorta), lacerated or crushed organs, hematomas, contusions, crushed or fractured bones, and severed spinal cord.

Causes

Blunt force trauma is often caused by motor vehicle accidents in which the body is slammed into a steering wheel or dashboard. This slamming action, caused by the rapid deceleration of the vehicle, may cause contusions or rupturing of internal organs. Another common type of blunt force trauma is an accidental fall. The many other possible causes of blunt force trauma include assault by another person (through clubbing with an object, hitting, kicking, or punching) and sporting accidents.

When blunt force trauma is caused by a beating or clubbing, the type of weapon used by the assailant can often be identified by the characteristics of the wound. If the wound shows characteristics that can identify only a class of instrument (as opposed to the specific type of instrument) as the weapon, such as a bone fracture showing smooth, curved lines that could have been made by any smooth weapon, these are called “class characteristics” of the weapon. At times, however, a specific weapon can be identified by the distinctive marks it has left on skin, bone, or other tissues. For instance, a hammer that had individualized marks of wear on it before it was used to inflict wounds could leave those specific marks on the victim. These are called “individual characteristics” of the weapon.

A single weapon can also cause a variety of wounds. For example, if a shovel is used as a weapon, it may cause a large flat wound if the back of the shovel is used. The same shovel wielded so that its side or blade struck the victim would produce a sharp, linear wound.

In addition to examination of the victim’s injuries, blood spatter analysis can provide clues as to the type of weapon used in a situation involving blunt force trauma, the strength of the person wielding the weapon, and the relative spacing of the victim and the attacker.

Injuries

Abdominal trauma is the most common type of blunt force trauma, and the liver, spleen, and small intestine can be affected. This often happens during a car accident, which may cause organ rupture.

Abrasions, or scrapes, are also often seen in cases of blunt force trauma. These injuries result when the skin is forcefully rubbed away by a rough surface, such as asphalt. Abrasions are usually only surface injuries. Lacerations may also occur; these can be either external or internal injuries, damaging the skin and penetrating into other tissues deeper within the body, such as muscles or organs.

In addition to other head injuries, such as skull fracture, that can result from blunt force trauma, the brain can also be damaged by the force of the blow. This can cause damage to the nerve cells deep inside the brain, even when there is no breaking of the skin.

Contusions, or bruises, from blunt force trauma can be either internal or external injuries. Bruises happen when blood vessels are damaged and begin to leak blood into surrounding tissues. Bruising on the skin surface shows up as swelling of the tissues and dark shades of color (blue, red, or purple). The amount of discoloration can vary with a person’s age and weight: Older people and those who are heavier may show more bruising than younger and less heavy people. Deep bruising caused by extreme blunt force can occur so far inside the body that nothing shows on the surface; such injuries can be seen only with the aid of technologies such as magnetic resonance imaging (MRI). Contusions of the brain may not be noticeable at all from surface injuries; they may manifest themselves only through neurological symptoms such as confusion and weakness.

Bibliography

DiMaio, Vincent J. M., and Suzanna E. Dana. Handbook of Forensic Pathology. 2d ed. Boca Raton, Fla.: CRC Press, 2007.

Ferllini, Roxana, ed. Forensic Archaeology and Human Rights Violations. Springfield, Ill.: Charles C Thomas, 2007.

Moore, Ernest E., Kenneth L. Mattox, and David V. Feliciano. Trauma Manual. 4th ed. New York: McGraw-Hill, 2003.

Shkrum, Michael J., and David A. Ramsay. Forensic Pathology of Trauma: Common Problems for the Pathologist. Totowa, N.J.: Humana Press, 2007.

Wilson, William C., Christopher M. Grande, and David B. Hoyt, eds. Trauma: Critical Care. Vol. 2. New York: Informa Healthcare, 2007.