It is common knowledge that whiplash-associated disorders are soft-tissue-related. Rear-end crashes account for a majority of trauma. Specific objective diagnoses have eluded clinicians because of the soft tissue nature of the disorder. Sophisticated tools such as magnetic resonance images (MRI) are inconclusive. The disorder is recognized in the Western world with significant societal impact and staggering economic costs. An increased level of awareness towards safety from the vehicle user coupled with the above factors and an interest by the automotive community to improve vehicle component designs have accelerated research in the area of whiplash-associated disorders from various perspectives. One of the main emphases has been to clearly delineate the mechanisms of the disorder. Consequently, the objective of this article is to describe the postulated mechanisms of injury and biomechanical studies attempting to prove the hypotheses. Results indicate that structures such as the facet joint are involved in chronic pain, and the kinematics of this joint are such that it undergoes characteristic motions during the early stages of rear impact acceleration. The presence of the transient nonphysiologic reverse curve, i.e. upper head-neck flexion is attributed to headaches, and the concomitant existence of lower cervical extension (particularly the inferior facet joints) during the early stages of rear impact acceleration are attributed to the mechanism of neck pain in whiplash. These studies have provided a fundamental basis for understanding the mechanism of the two most common complaints in whiplash, headache and neck pain. (Author/publisher).
Abstract