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.