Autopsy & forensics

Types of injuries

Motor vehicle deaths

Last author update: 1 August 2012
Last staff update: 26 August 2019

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PubMed search: "Motor vehicle" death forensic

Lindsey Harle, M.D.
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Cite this page: Harle L. Motor vehicle deaths. website. Accessed March 22nd, 2023.
Types of collisions
Frontal impact:
  • Most common (80%); occurs when two vehicles collide head on, or when a single vehicle hits a stationary object head on
  • Vehicle occupants continue moving forward due to kinetic energy; impacting the windshield and dashboard
  • Drivers show trauma of the anterior head due to impact with windshield or visor; may show skull fractures, atlantooccipital dislocation, neck fractures, diffuse axonal injury
  • Drivers may have chest injuries due to impact with the steering wheel, with sternal and rib fractures, pulmonary contusions and lacerations (due to rib fractures), cardiac laceration / contusion, aortic dissection, hepatic and splenic lacerations
  • May show pattern impact injury of the steering wheel
  • Drivers may show wrist or forearm fractures if hands were positioned on wheel at time of impact
  • Drivers may have patellar or femoral fractures due to impact with dashboard; or ankle fractures
  • "Dicing injuries" to the left face and left arm: small abrasions / lacerations on driver due to shattering of the driver side window
  • Front seat passengers: injuries similar to driver, but no steering wheel impact
  • Dicing injuries of the right face and right arm due to shattering of passenger side window
  • Unrestrained rear passengers may be thrown to front compartment of vehicle

Side impact:
  • Usually due to one vehicle impacting the side of another vehicle
  • All injuries seen in frontal impact collisions can occur
  • Injuries should be more severe on side of impact; individuals on impacted side should have more severe injuries than those on the opposite side

Rear impact:
  • May cause "acceleration" injuries (e.g. whiplash) which tend to be less severe

  • Tend to be more severe; many different injury patterns can occur
  • May cause traumatic asphyxia if individual is ejected and becomes trapped beneath vehicle
  • May see pattern injury from seatbelts; pattern should correspond to position of individual in car (e.g. driver vs. passenger)
  • Seatbelts can produce mesenteric, omental, or bowel contusions / lacerations
Suicidal motor vehicle accidents
  • Vehicle directly collides with fixed object or another vehicle
  • No signs of braking at scene
  • Decedent may have history of suicidal ideation or suicide attempts
Pedestrian deaths
Factors influencing injury pattern:
  • Vehicle speed: high speed impact may cause pedestrian to be thrown over vehicle
  • Braking may result in pedestrian being "picked up" by vehicle or being thrown forward
  • Type of vehicle: larger vehicles that hit pedestrian above their center of gravity tend to knock them down rather than pick them up
  • Size / age of pedestrian: impact below pedestrian’s center of gravity causes them to be lifted and thrown

Injuries sustained by pedestrians:
  • Tire / tread marks: on skin or clothing; can link pedestrian to vehicle
  • Pattern injuries: in addition to tire marks, can include impressions of bumper, headlights, or other parts of vehicle; can be used to link pedestrian to vehicle
  • Bumper fractures: occur when bumper strikes pedestrian's lower extremities; may not be associated with overlying cutaneous injury
  • Measure distance from heel to estimate bumper height
  • Contusion pockets: collections of blood in subcutaneous tissue or muscle; due to impact with hood or bumper
  • "Stretch" lacerations of inguinal folds: due to overstretching of body at hip joint; appear yellow and dry
  • Suicidal pedestrian deaths: need witness information and decedent history of suicidal ideation to corroborate
Motorcycle deaths
Types of injury:
  • Head trauma: most common lethal injury; may occur even in individuals wearing a helmet
  • Basilar skull fracture is most common
  • Motorcycle passengers tend to fall backwards, producing lacerations and fractures of posterior head
  • Brush abrasions ("road rash") on exposed skin
  • Traumatic asphyxia: may occur if motorcycle lands on individual
Bicycle deaths
  • Most bicycle accidents produce only minor trauma
  • Degree of injury is largely related to speed of the impact
  • Bicycle spoke injury: occurs when leg or foot passes through wheel spokes; causes crushing / avulsion of soft tissues; more common in children
Evidence to examine
  • Toxicology of driver, passenger, and pedestrian, to include carbon monoxide for vehicle occupants
  • Trace evidence: hair, blood, clothing fibers, glass chips, or paint chips can be used to link a car to a pedestrian death, or to determine a person's position in vehicle
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