Cushioning the blow
WHIPLASH is one of the most common injuries resulting from automobile crashes, affecting about 1 million Americans each year. But adjusting your car’s head restraint properly can minimize the risk of injury, according to a new study. Using a computer model, researchers at the Medical College of Wisconsin have shown that positioning the head restraint very close to the back of the head -- no more than 2.4 inches away from it -- provides the best protection.
Brian Stemper, an assistant professor of neurosurgery at the college and lead author of the study, says that researchers have only recently begun to learn more about how whiplash injuries occur. More recent video and computer analysis shows that, as a vehicle is struck from behind, the chest initially moves forward while the head is stationary. This sheering motion between head and chest causes injury to the ligaments and discs of the spine.
Positioning the head restraint to within 2.4 inches minimizes the sheering motion and keeps the ligament stretch within a range that would prevent injury, reported the study, published in the journal Accident Analysis and Prevention. “You want to raise it so the center of the back of your head can contact it,” Stemper says. “And you want to minimize the distance.”
Unfortunately, he adds, studies show that most people don’t have their head restraint positioned correctly. “Most of the time people don’t adjust their head restraint at all.”
