Approximately 20% of car-to-car accidents in the U.S. are believed to be rear-end collisions, and approximately 10% of the whiplash injuries resulting from rear-end impacts require longer term therapy. Thus, the societal cost of whiplash injuries is a common problem worldwide, so its prevention is a hot topic globally. However, whiplash injuries involve a very wide range of symptoms, such as surgical symptoms, neurological symptoms, audiological symptoms, otorhinolaryngological symptoms, sense-ofbalance symptoms, teeth-occlusion symptoms, etc. Whiplash injuries have such subtle characteristics that patients themselves complain of various symptoms in addition to these diverse symptoms, even in the absence of objective medical evidence, at times.

We have developed an AM 50%-tile finite-element model of the whole human body, called THUMS (Total HUman Model for Safety), to study the mechanisms of human-body injury during a collision. In this research, the same model was utilized to study the mechanisms of injury to the cervical vertebrae region from whiplash during a collision. We developed a cervical spine model that newly incorporates spinal cord, nerve roots, cerebrospinal fluid (CSF), spinal dura mater, etc., and then verified the accuracy of this model by means of cadaver test data. Its validity was examined on the basis of various hypotheses studied to date:​ the myalgia hypothesis, the theory of nerve-root pressure caused by compression of the spinal cord and nerve roots, the theory of facet joint impingement, the theory of the shear deformation of facet joints and ligaments, etc. Also, whiplash symptoms resulting from the leakage of CSF (i.e., the low intracranial pressure syndrome), which recently has attracted attention in Japan, also are evaluated with respect to the existence of spinal dura mater spinalis injury.