March 16, 2000 (Atlanta) -- It's stating the obvious to say that people involved in car crashes not only want to survive the accident, but walk away from it, too.
But, according to statistics from the National Spinal Cord Injury Database, since 1991, motor vehicle crashes have accounted for about 36% of all new spinal cord injuries in the U.S., and car wrecks remain the No. 1 cause of spinal injury.
A new study from the University of Pittsburgh Medical Center shows that using a seatbelt in combination with an airbag can significantly decrease the risk of spinal injury in an auto accident.
"There appears to be a 35-42% reduction in the probability that you would sustain a spinal injury when you're wearing both a seatbelt and have an airbag," lead author Michael A. Catino, MD, tells WebMD. Catino presented his study this week at a meeting of the American Association of Orthopaedic Surgeons in Orlando, Fla.
Catino's study contained nearly 7,200 people who were admitted to Pennsylvania trauma centers with spinal injuries after a car accident from 1990 to 1997. The accident injuries were put into four categories: use of air bags only, seat belts only, seat belts and air bags, and no protective devices.
Using the seat belts and air bags category as the baseline, Catino and colleagues found the incidence of spinal injury in an auto accident is 35% greater if only an air bag is deployed, 37% greater if no protective device was used, and 42% greater if only a seat belt is used.
The disparity in the numbers, Catino says, could in part come from the fact that the sample sizes of each group were vastly different. "It's a small study," he tells WebMD. "But, on the flipside, could you make an argument that the seatbelt or the shoulder restraint [alone] makes injury to the cervical spine more common? I mean it's certainly possible." However, Catino says he can't claim that his study has definitively shown that and more investigation is needed.
"All we're able to show is that with the use of both devices, there appears to be a decreased risk of sustaining a spinal injury compared to the other protective devices used alone," Catino says.
Catino emphasizes that using both a seat belt and an airbag are not the only precautions to follow. National Highway Traffic Safety Administration (NHTSA) recommendations should be heeded, he advises. These include maintaining 10 inches from the sternum to the steering wheel, always transporting children in rear-facing child seats in the back seat (because in the front seat their head is too close to the airbag), and always transporting children less than 12 years of age in the back seat as well.
Ricardo Martinez, MD, the former administrator of the NHTSA, tells WebMD there are lots of studies focusing on benefits to the head, chest, and abdominal area from airbags or seatbelts. But, if a person chooses to rely on just one of those, it's a "trade-off."
"It's well known that you get more cervical spine strain with a lap-shoulder belt, but what you get is less chest and less abdominal injuries. ... Most of the studies show that there is a decrease in chest and head injury with the airbags, and if you look -- that's where the benefits are. ... Some studies actually show a greater percentage of lower extremity injuries because people are surviving who may have otherwise died," Martinez says. Martinez is now vice president of health affairs for WebMD.
He says the "gold standard" in the study is the airbag-seatbelt combination. "The head and chest operate independently, and that often creates a neck injury. So, just holding back the chest with a lap shoulder belt doesn't keep the head from going forward and putting stress on the spine, and just having the airbag doesn't keep the head and the chest back together. ... So, restraining the chest and then using the airbag for the head and chest together is probably the best combination, that's the message they're making," Martinez tells WebMD.
- Motor vehicle crashes are the No. 1 cause of spinal cord injuries, accounting for 36% of all such injuries.
- People who use a seatbelt in combination with an airbag can significantly reduce their risk of spinal injury from a car accident.
- To ensure that air bags are the most effective, drivers should maintain 10 inches between the sternum and the steering wheel, and children under 12 should sit in the back seat.