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.
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