Abstract
Introduction. AIS1 neck injuries are the most common type of injury resulting from rear-end impacts. In 1998, Whiplash Protection System (WHIPS) was introduced in Volvo cars, comprising of an energy absorbing recliner mechanism for the front seats.
Method. Since 1999, rear-end impacts of Volvo cars in Sweden have been investigated on a regular basis, including one-year post accident follow-up. A total of 1,608 front seat occupants (above 14 years of age) have been analyzed regarding influencing factors on incidence of AIS1 neck injuries. The AIS1 neck injury reducing effect of WHIPS was calculated from a subset of 324 front seat occupants who had no prior neck problems and who had undergone a moderate severity rear end impact. Occupants in cars equipped with WHIPS are compared to those in Volvo cars of model year 1999 without WHIPS.
Results and Conclusions. Prior neck problems are a significant influential factor and should be taken into consideration. Sitting posture, such as turned head and increased head to head restraint distance significantly increases AIS1 neck injury rates. For the selection made in this study, the injury-reducing effect of WHIPS as compared to previous Volvo seats is 33% (p = 0.002) for initial neck symptoms and 53% (p = 0.01) for neck symptoms lasting longer than one year. The injury reducing effect is higher for women than for men.