Note: The article has a picture of what happens when a shifter gets impaled in a leg. If you are queasy, don’t click. If you click, don’t complain.
During my career as a trauma surgeon taking care of patients injured in motor vehicle collisions (MVCs), I have all too frequently heard, “he would have died had he been wearing his seat belt.” Late one Friday night, I heard those words from the family of Mr. Smith. Whenever presented the opportunity to lay to rest misguided beliefs, I take off the white coat, stand on the bully pulpit and start preaching.
In a MVC, there are actually three collisions that occur and are governed by Newton’s laws. Newton’s first law states that objects at rest (or in motion) remain at rest (or in motion) unless acted upon by a force. Newtons third law says that for every action (force) there is an equal and opposite reaction (force). To understand how these laws apply to a MVC and the occupants, the simplified example of a vehicle striking an immovable concrete barrier will be used. When the vehicle strikes the concrete barrier, the vehicle in motion will come to a complete rest because the concrete barrier will deliver an equal and opposite force. The vehicle striking the concrete barrier is the fist collision. In Mr. Smith’s case, he lost control of his pickup truck and had a right frontal offset collision with a bridge abutment.
The second collision is the occupant versus the vehicle. Just as the vehicle comes to a complete stop, so must the occupant. The unrestrained occupant will stay in motion until striking the interior of the vehicle. A restrained occupant almost simultaneously (understanding seatbelt laxity and deformability of the human body) decelerates with the vehicle as the front of the vehicle collapses striking the barrier. The length of time the occupant takes to come to a stop is called the crash pulse. Another to way to describe the crash pulse is the time it takes to decelerate. The longer the crash pulse, the likelihood of survivability increases and injury decreases. Air bags augment the three point belt lengthening the crash pulse and decreasing contact with injury-producing contact surfaces such as the steering wheel and windshield. Mr. Smith was not wearing his seatbelt so he stayed in motion until he struck the interior of the vehicle. Since the collision was a right frontal offset, he went to to the right of the steering wheel. Mr. Smith’s face struck the windshield on the passenger side, his chest and abdomen the dash, and his thigh the shifter knob.
The third collision are the internal organs of the occupant. In summary, the vehicle hits the barrier, coming to a stop, and then the occupant comes to stop. Imagine the chest wall hitting the seatbelt, then the airbag and finally the steering wheel (if severe enough of an impact). The heart continues in forward motion decelerating until it strikes the back of the chest wall. In Mr. Smiths collision, his heart was not injured but his spleen cracked when it decelerated and struck his abdominal wall. A multitude of variables and forces occur in a MVC, but just as crash impulse time plays a role, so does the area of distribution of force. The greater the area the deceleration force can be distributed, the chance for injury decreases. For example, consider the same deceleration force against an unrestrained occupant’s chest striking a pointed 1950s steering wheel versus a three-point seatbelt and airbag. When Mr. Smith’s leg struck the shifter knob, it impaled his leg.
Impalements are unusual, infrequent, quite spectacular, and always draw a crowd in the trauma bay. Mr. Smith was fortunate and only skin and muscle were injured. I was able to extract the shifter in the trauma bay and then I repaired his leg in the operating room.
No two real world accidents are the same and there are an infinite number of variables. Therefore, behavior behind the wheel should not based upon anecdotal evidence and “what if” scenarios. Rather, behavior should be based upon statistical analysis and probabilities of MVCs and crash testing.
Mr. Smith recovered from his facial fractures and lacerations, rib fractures, splenic laceration and impalement. He progressed well with physical therapy and was walking with crutches. Prior to discharge, I took off the white coat and stood up on the pulpit. As always, I put away the doctor talk and explained things in plain English. I told Mr. Smith that there have been tremendous advances in automotive and racing safety.
The days of not wearing a seat belt for fear of being trapped in your car and burned alive should be a long distant memory. In reality, only 0.5% of MVCs end in fire or submersion. To not wear your seatbelt for a 0.5% probability simply does not make sense. The more likely result of not wearing a seat belt is ejection from the vehicle. “Doc, you should see the car, it was crushed so bad, he would have died had he stayed in it.” I certainly have seen MVCs where the occupants survived because they were ejected. However, if you are ejected from a vehicle in a MVC, you are four times more likely to be killed as those who remain inside the vehicle. I am not rolling the dice at those odds.
The greatest single advancement in automotive safety has been the seat belt. Seat belts reduce serious injury and deaths in MVC by 50%. Airbags do augment the effectiveness of seat belts, but are not a substitute. Mr. Smith was very appreciative of my care and taking the time to talk to him about wearing his seat belt. But as I have learned all too often in life, entrenched beliefs are rarely altered by exposure to fact. Hopefully, you have already made up your mind and religiously click your seat belt every time you get in a vehicle.
Dr. Delaney is a trauma surgeon, lifelong automotive enthusiast, shade tree mechanic, race fan, and motor vehicle safety expert. During his career, he has seen injuries one just cannot make up, and many of them involve motor vehicle crashes. He has been telling these stories for years, and he thinks it’s time to write them down.