Clinical and kinematic responses to neck injuries in low-speed reverse motor vehicle collision tests: a human volunteer study.

BACKGROUND

Whiplash-associated disorders (WAD) are commonly attributed to rapid cervical acceleration–deceleration during motor vehicle collisions; however, the clinical significance of low-speed reverse collisions remains uncertain.

METHODS

This prospective experimental study evaluated clinical, radiological, neurophysiological, and biomechanical responses in twelve healthy adult volunteers (6 males, 6 females; mean age 31.2 ± 8.5 years) exposed to controlled reverse collisions at an impact speed of 8 km/h. Assessments included pre- and post-collision X-ray and MRI imaging, electromyography and nerve conduction studies, self-reported pain evaluation, and kinematic analysis of cervical motion, neck torque, and the Neck Injury Criterion (NIC).

RESULTS

No structural cervical spine injuries were identified on imaging, although subtle straightening of cervical lordosis was observed in two participants. Electromyography and nerve conduction studies demonstrated statistically significant changes in selected parameters; however, all values remained within normal physiological ranges, with no findings indicative of clinically meaningful nerve injury. Self-reported pain was mild and transient, most frequently involving the cervical and lumbar regions immediately after collision and declining substantially within one week. Kinematic analysis showed that 50% of participants exceeded 30 N·m in peak neck torque, whereas all NIC values remained well below established injury thresholds.

CONCLUSION

In healthy adults, low-speed reverse collisions produced measurable biomechanical loads and transient musculoskeletal responses without evidence of clinically significant cervical spine injury. These findings support the use of integrated multimodal assessment—including imaging, neurophysiological testing, pain reporting, and kinematic indices—to differentiate benign biomechanical adaptations from true injury in low-velocity collision contexts. Further longitudinal studies are warranted to evaluate individual variability and the persistence of subtle cervical alignment changes.