PHTLS Kinematics of Trauma 4 â Questions and Answers
Question 1: A motorcyclist traveling at 55 mph strikes a guardrail and is ejected. Which injury pattern should be the highest priority concern based on kinematics?
- Isolated extremity fractures
- Multisystem trauma including head, thorax, and abdomen (Correct answer)
- Soft tissue lacerations only
- Cervical strain without bony injury
Correct answer: Multisystem trauma including head, thorax, and abdomen
Ejection from a motorcycle at highway speed subjects the rider to multiple high-energy impacts, making multisystem trauma the expected injury pattern.
Question 2: In a frontal vehicle collision, the 'down-and-under' pathway most commonly results in which injuries?
- Aortic transection and rib fractures
- Knee, femur, and hip injuries from dashboard impact (Correct answer)
- Cervical spine hyperextension
- Abdominal organ rupture from steering wheel
Correct answer: Knee, femur, and hip injuries from dashboard impact
The down-and-under pathway drives the knees into the dashboard, transmitting force up through the femur and into the hip joint.
Question 3: A 250-lb patient and a 125-lb patient are both involved in identical crashes at 40 mph. Which statement best describes the energy involved?
- Both patients have the same kinetic energy because speed is equal
- The heavier patient has twice the kinetic energy (Correct answer)
- The lighter patient has twice the kinetic energy due to less resistance
- Kinetic energy is unaffected by mass in vehicle collisions
Correct answer: The heavier patient has twice the kinetic energy
Kinetic energy equals œmv², so doubling the mass doubles the kinetic energy when velocity is held constant.
Question 4: Which anatomical region is at greatest risk during a lateral (T-bone) vehicle collision on the driver's side?
- Posterior thorax and lumbar spine
- Ipsilateral clavicle, ribs, pelvis, and head (Correct answer)
- Contralateral knee and ankle
- Bilateral lower extremities
Correct answer: Ipsilateral clavicle, ribs, pelvis, and head
A lateral impact directly compresses the side of the vehicle into the driver, causing ipsilateral clavicle, rib, pelvic, and head injuries.
Question 5: A patient was struck by a vehicle while walking. The paramedic notes the bumper height corresponds to the patient's mid-thigh. What is the FIRST injury expected in the classic pedestrian-vs-vehicle pattern?
- Head strike on the hood
- Torso impact with the windshield
- Femur/tibia fracture at bumper level (Correct answer)
- Spinal injury from ground impact
Correct answer: Femur/tibia fracture at bumper level
The initial impact of the bumper against the lower extremity at bumper height is the first of three phases in a pedestrian collision.
Question 6: Which factor most significantly increases the severity of a blast injury in an enclosed space compared to an open field?
- Longer duration of the positive pressure wave
- Reflection and amplification of the pressure wave off walls (Correct answer)
- Increased fragmentation from structural materials
- Greater thermal exposure from the fireball
Correct answer: Reflection and amplification of the pressure wave off walls
Enclosed spaces cause blast waves to reflect off walls and compound, dramatically increasing peak overpressure exposure to victims.
Question 7: A patient fell from a 20-foot ladder onto concrete. Using the energy of motion principles, what finding on scene best predicts injury severity?
- Patient's age and pre-existing conditions only
- The height of the fall and the stopping distance on impact (Correct answer)
- Whether the patient was wearing a hard hat
- The number of bystanders who witnessed the fall
Correct answer: The height of the fall and the stopping distance on impact
Fall height determines the velocity at impact, and stopping distance (hard concrete vs. soft surface) determines the deceleration force applied to the body.
PHTLS Kinematics of Trauma 4
A motorcyclist traveling at 55 mph strikes a guardrail and is ejected.
Which injury pattern should be the highest priority concern based on kinematics?