lmfr kinetics

Kinetics of Trauma

• There are several forms of kinetics of trauma.

• We are only going to discuss kinetics of blunt trauma in this course.

Objectives

• The student will understand the mathmatics of kinetic energy.

• The student will understand the different types of blunt trauma.

• The student will understand where and how crumple zones were developed.

• The student will understand how different vehicles are affected by kinetic energy.

Kinetics of Blunt Trauma

• Inertia “A body in motion will remain in motion unless

acted upon by an outside force.” “A body at rest will remain at rest unless acted

upon by an outside force.”• Conservation of Energy

“Energy can neither be created nor destroyed. It is only changed from one form to another.”

• Kinetic versus Potential Energy


• Kinetic Energy Energy in Motion

Double Weight = Double Energy Double Speed = Quadruple Energy

SPEED IS THE GREATESTDETERMINANT

2

)()( 2speedVelocityweightMassKE


• Force

Emphasizes the importance of rate at which an object changes speed (acceleration or deceleration)

onAcceleratiMassForce


• Blunt Closed injury Indirect injury to underlying structures Transmission of energy into the body• Tearing of muscle, vessels and bone• Rupture of solid organs• Organ injury

– Ligamentum teres

Blunt Trauma: Automobile Crashes

• Restraints Seatbelts

• Occupant slows with the vehicle• Shoulder and Lap belts MUST be worn together

– Injuries if worn separately Airbags (SRS)

• Reduce blunt chest trauma• Cause: Hand, Forearm, & Facial Injury• Check for steering wheel deformity• Side Airbags

Child Safety Seats• Infants and Small Children: Rear facing• Older Child: Forward facin


• Types of Impact Frontal: 32% Lateral: 15% Rotational: 38%• Left & Right – Front & Rear

Rear-end: 9% Rollover: 6%


• Lateral Impact 15% of MVC’s but 22% of deaths Upper extremity injury Rib, clavicle, humerus, pelvis, femur fracture Lateral compression• Ruptured diaphragm, Spleen fracture, Aortic injury

• Rotational Vehicle struck at oblique angle Less serious injuries unless strike a secondary object

• Rear-end Seat propels the occupant forward Head is forced backwards

• Stretching of neck muscles and ligaments• Hyperextension & hyperflexion

• Rollover Multiple points of impact Ejection or partial ejection Less injury with restraints

• Vehicular Mortality from injuries to the body Head: 48% Internal (Torso): 37% Spinal & Chest fracture: 8% Extremity fracture: 2% All Other: 5%

Recreational Vehicle Accidents

• Lack structure and restraint system• Types of Vehicles

Snowmobiles Personal watercraft ATV’s Motorcycles

• Modern technology of vehicles have addressed some issues of kinetic energy in MVCs. The idea is to transfer the energy to anything other than the passenger.

• Examples:– Seat belts– Air bags– Crumple zones in vehicles– Safety zones (cell) in vehicles

• The idea is to address kinetic energy is to develop crumple (crush) zones that slow down energy (much like brakes on a car) before it reaches the passengers of a vehicle.

• The larger the crumple zone the less energy transferred to the passengers.

• Crumple zone were invented by Mercedes in 1952 and first used in their vehicles.

• The older U.S. cars were more ridged in the body of the vehicle. This caused less damage to the vehicle. But this caused more energy being transferred to the passengers. Resulting in more deaths.

• We started seeing crumple zones and safety zones in U.S. vehicles in the late 1970’s.

• That’s why you are seeing a lot of damage to vehicles in slower speeds. They have developed better crumple zones to absorb more energy and stronger safety zones for passengers of vehicles.

• If you have a small vehicle vs. a large vehicle, you still have a lot of kinetic energy and MOI.

• If you have a vehicle traveling at a high rate of speed vs. a stationary object you still have a lot of kinetic energy and MOI.

• If you have a patient on a recreational vehicle without restraint devices vs. anything. You still have elevated MOI.

• Smaller vehicles obviously have smaller crumple zones, resulting more energy getting to the passengers.

• Side impacts in all vehicles result in more energy getting to the passengers, possibly causing greater injuries to the passengers.

An example of vehicles before crumple zones with little damage to the vehicle, but poor

outcome for the passenger

Not much damage to the vehicle, but a fatal injuries to the passenger

The 1959 Mercedes-Benz 220S/220SE. The first crumple zone vehicle.

Example of vehicle safety technology

Excellent example of small vehicle vs. large vehicle. Sometimes it doesn’t matter how much

safety equipment you have on the vehicle.

Another example of bigger vs. smaller. Possibly a better outcome for the

passenger.

Example of small vehicle safety equipment

Example of how energy is transferred through out the vehicle to slow energy down.

Other example of crumple zones.

What it looks like when a vehicle “crumples on impact”

An example of energy being displaced through out the vehicle.

Good example of the safety cell collapsing to absorb energy, but a lot of intrusion into the passenger area.

An example of a vehicle struck in the side. You can see why the passenger struck from the side has less

protection and more potential for injury.

Automobile CrashesCrash Evaluation

• Cause of Crash Weather & visibility? Alcohol involved? Skid marks?

• Auto Interior Starring of windshield? Steering wheel

deformity? Dash deformity? Intrusion? Air bags deployed? Seat belt on the patient?

• Collision Questions How did collision

occur? Direction? Speed? Similar/Different sized? Secondary collisions?I.E. patient hitting the seatbelt, steering wheel, windshield, flying debris etc.

• Serious injuries can occur with high and low speed collision.

• Types of Impact Frontal Angular Sliding Ejection, this is a result of almost all motorcycle

crashes• Initial Bike/Object Collision• Rider/Object• Rider/Ground

Blunt Trauma: Motorcycle / ATV Crashes

In these cases, the motorcyclist always loses and gets ejected.

• Remember the types of injuries the patient can acquire with impacts with anything in the vehicle.– Tearing of internal organs from sudden de-

acceleration– Broken bones from transferred energy– Bursting injuries to organs from de-acceleration– Head injuries un-restrained objects flying around

in the vehicle

lmfr kinetics

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