Whiplash syndrome - Kinematic factors influencing pain patterns

Study Design. The overall, local, and segmental kinematic responses of inta ct human cadaver head-neck complexes undergoing an inertia-type rear-end im pact were quantified. Hish-speed, high-resolution digital video data of ind ividual facet joint motions during the event were statistically evaluated. Objectives. To deduce the potential for various vertebral column components to be exposed to adverse strains that could result in their participation as pain generators, and to evaluate the abnormal motions that occur during this traumatic event. Summary of Background Data. The vertebral column is known to incur a nonphy siologic curvature during the application of an inertial-type rear-end impa ct. No previous studies, however, have quantified the local component motio ns (facet joint compression and sliding) that occur as a result of rear-imp act loading. Methods. Intact human cadaver head-neck complexes underwent in ertia-type rear-end impact with predominant moments in the sagittal plane. High-resolution digital video was used to track the motions of individual f acet joints during the event. Localized angular motion changes at each vert ebral segment were analyzed to quantify the abnormal curvature changes. Fac et joint motions were analyzed statistically to obtain differences between anterior and posterior strains. Results. The spine initially assumed an S-curve, with the upper spinal leve ls in flexion and the lower spinal levels in extension. The upper C-spine f lexion occurred early in the event (approximately 60 ms) during the time th e head maintained its static inertia. The lower cervical spine facet joints demonstrated statistically greater compressive motions in the dorsal aspec t than in the ventral aspect, whereas the sliding anteroposterior motions w ere the same. Conclusions. The nonphysiologic kinematic responses during a whiplash impac t may induce stresses in certain upper cervical neural structures or lower facet joints, resulting in possible compromise sufficient to elicit either neuropathic or nociceptive pain. These dynamic alterations of the upper lev el (occiput to C2) could impart potentially adverse forces To related neura l structures, with subsequent development of a neuropathic pain process. Th e pinching of the lower facet joints may lead to potential for local tissue injury and nociceptive pain.