Bones and Trauma

Bone Information After a determination of gender, age, height and race has been made, the next step is to study the bones to determine cause and manner of death. If the death is a homicide, accident or suicide, skeletal trauma is usually apparent.

X Rays The Medical Examiner will take x rays of the corpse to look for signs of trauma. Many skeletal injuries are the result of applied forces.

X-Rays of Broken Bones

Effects of Force on Bones How a bone breaks, depends on the type of force that was applied to the bone. There are 5 types of forces that may cause bone fractures: compression, shearing, bending, torsion and tension. Since a force is a push or pull, these 5 types involve one of these motions.

Compression A compression force pushes down on a bone. The fracture lines will be numerous, wide- reaching and radiate from the point of impact. This most likely compressed bone is the skull.

Result of a Compression Force from a Hammer

Result of Compression Forces from a baseball bat.

Shearing When a force is applied to one section of the bone while the rest of the bone is immobilized a shearing type of fracture occurs. Shearing can occur in an accident when someone is trying to stop themselves from falling or when a victim is dismembered with a sharp instrument such as a saw.

A deer leg cut off with a saw Example of a bone that sheared when the person tried to stop themselves from falling.

Bending This is the most common of the five forces. This force impacts the bone at a right angle causing a triangular break through the cross section. Breaks are usually clean in adults, but “green stick” in children. A parry fracture of the ulna bone is often seen in deaths from violent struggle.

Break caused by a bending force.

Green Stick Break Example of a bending force break.

Torsion Torsion is a twisting force. One end of the bone is twisted while the other end of the bone remains stationary. These forces occur in accidents such as skiing and child abuse cases.

Torsion arm fractures in children.

Tension A tension force pulls on the length of the bone. These forces usually cause dislocations, but a part of the bone may break away if the force is strong enough. These occur most often in accidents.

Examples of dislocated bones.

Traumas, Forces and Injuries Blunt Force Trauma- injury caused by blow from a wide instrument that has a flat or round surface. This trauma involves compression, shearing and bending forces. Examples: Falling on a hard surface, car accidents and a beating with a club. The corsets that were wore by women in the Victorian era were a slow form of blunt force trauma.

Examples of Blunt Force Trauma

Traumas, Forces and Injuries Projectile trauma- creates a wound that displaces bone with radiating fracture lines from point of impact. Compression force is the type of force associated with projectiles. Projectile trauma is generally caused by bullets.

Examples of Projectile Trauma

More examples of Projectile trauma

Traumas, Forces and Injuries Sharp Force Trauma- occurs when a compression or shearing force is applied in a narrow area. In death by strangulation the hyoid bone is fractured.

Hyoid Bone Fracture

The Importance of Understanding Forces An understanding of the types of trauma sustained by skeletal remains will help the Medical Examiner determine and/or confirm the cause and manner of death.