[Whiplash trauma of the cervical vertebrae in traffic: biomechanical and expert-opinion aspects]

Abstract

The indirect injury mechanisms of the cervical spine should be subdivided into "non-contact injury" of the cervical spine, without head impact, by definition (hyperflexion or hyperextension), sometimes also called whiplash injury mechanism, and bending mechanism due to head contact, i.e. "contact injury" (hyperflexion, hyperextension, lateral bending, axial compression). The term "whiplash" is, in strict biomechanical terms, very often incorrect since it implies a biphasic motion (hyperextension and hyperflexion, or vice versa); in traffic collisions, however, its second phase is insignificant. The terms used for the injuries themselves should be taken from the classic morphology (fracture, luxation, distorsion etc.). The severity of the injury alone offers no hint as to the mechanical severity of the collision, which is established only by a mathematical reconstruction of the collision dynamics also taking into account such criteria as collision angle, seat belts, head restraint position etc. Significant cervical spine injury due to non-contact mechanism is very rare if car damage is only minor; however, head contact inducing cervical bending can lead to severe cervical injuries even with minor car damage. In the latter case the patient should not be treated as a malingerer. Moreover, if more than two vehicles are involved the reconstruction of the accident is greatly facilitated if the lesion can be proven to be a "contact" or "non-contact" injury (legal implications, insurance payments). The (rare) severe cervical spine injuries in seat belt wearers are not caused by the restraining effect of the belt but by bending and injuring of the neck due to head contact which often is not completely avoidable (justification of mandatory seat belt law).