Whiplash injuries resulting from rear impacts are one of the most important injury categories with regard to long-term consequences. Most rear impacts lead to no injury or to symptoms that are temporary. Impacts where the duration of symptoms differs need to be separated in analyses in order to isolate representative rear impact conditions in which more long-lasting whiplash injuries occur.
The aim of this study was to evaluate the influence of crash severity on symptoms duration of Whiplash Associated Disorders, WAD, separated for males and females, and for different grades of WAD (1-3) according to Quebec Task Force.
Since 1995, approximately 60 000 vehicles on the Swedish market have been equipped with crash pulse recorders measuring the acceleration time history in rear impacts. With the inclusion criteria of single rear-end crashes with a recorded crash pulse, and front seat occupants with no previous long-term AIS1 neck injury, 207 front-seat occupants in 150 crashes remained to be analyzed in this study, where the change of velocity and the crash pulse were measured.
A correlation was found between duration of symptoms and crash severity measured as mean acceleration and change of velocity. The risk of WAD symptoms for more than one month was found to be 20% at a change of velocity of approximately 8 km/h and at a mean acceleration approximately 5 g. A correlation was also found between grades of WAD and crash severity measured as mean acceleration and change of velocity. Out of all crashes with a recorded crash pulse only one out of 207 occupants sustained WAD symptoms for more than one month at mean acceleration below 3.0 g. Given the same crash severity, females had a higher risk of initial WAD symptoms than males.