You would think that the increased safety measures in motor vehicles these days would mean fewer injuries after accidents. But, in fact, the number of spine fractures has actually gone up. With the use of both a seat belt and an air bag, it seems like the opposite should be true. Why is that?
In this study, researchers take a look at the effect of combined seatbelt use and air bags on passengers in the front seat of automobiles. They report that in other studies, the use of these safety measures has reduced the number of deaths and bodily injuries. The use of an air bag without a seat belt results in more cervical neck spine and thoracic (upper back) fractures.
After studying crash data from police reports and hospital records, the authors found that the use of an air bag with the seatbelt produced more spinal fractures. But the severity of the fractures was less. The study took place in Wisconsin. Here’s how the numbers broke out:
Taking a closer look at the information available, it looks like more people are using the air bags without a seat belt. The study only included motor vehicle accidents (MVA) where the victims were not ejected. That’s because these patients are known to have a different pattern of injury compared with people who are thrown from the car. Only drivers or passengers over the age of 16 were included.
Since the researchers had access to the patients’ hospital records, it was possible to analyze and compare information on age, sex, severity of accident, type of vehicle, and use of seat belt and/or air bags. They found that spine fractures occurred more often in male truck drivers in a rural location.
Patients with spine fractures were more likely to be wearing only a seatbelt. Those who wore a seatbelt and had air bags that deployed had fewer spine fractures. The number of spine fractures was equal among patients who used only an air bag or who used no safety measures (no seat belt and no air bag).
Statistical analysis of the data showed that seat belt use alone increases the risk of spine fracture. The combined use of a seat belt and an air bag reduced the risk of cervical and thoracic spinal fractures but did not affect the number of lumbrosacral fractures. Relying only on an air bag (no seat belt) increased the risk of a severe thoracic fracture.
The authors could not say for sure why the overall rate of spinal fractures increased with the increased use of safety equipment. They suggested it’s possible that improved imaging technology reveals smaller, more minor fractures than in the past. The fact that the number of severe fractures has not increased suggests this might be the case.
Based on the results of this study, drivers and passengers are encouraged to wear their seat belts even when the vehicle has air bags installed. The risk of a spine fracture (and especially a severe one at that) is less with both safety measures in place. The use of seat belt alone or air bag alone is not advised.