Clinical and Kinematic Responses to Neck Injuries in Low-Speed Reverse Motor Vehicle Collision Tests: A Human Volunteer Study

Abstract Research question/objective: Low-speed motor vehicle collisions (MVCs), especially in reverse driving scenarios, frequently lead to neck pain complaints despite the absence of radiological evidence of injury. This raises concerns about ex-post moral hazard and overtreatment. To evaluate the clinical, neurophysiological, and biomechanical responses to low-speed reverse MVCs in healthy adults, and assess the potential for cervical spine injury. Methodology: This prospective experimental study involved 12 healthy adults who participated in controlled low-speed rear-end collisions while driving in reverse. Six vehicle combinations were used with alternating full and offset frontal impacts. Pre- and post-collision assessments included cervical spine X-rays, MRI, electromyography (EMG), and nerve conduction velocity (NCV) tests. Head-neck-trunk motions were captured via markerless 3D motion analysis, and biomechanical parameters such as torque, impulse, and Neck Injury Criterion (NIC) were calculated. Pain levels were self-reported using a numeric rating scale. Two-way repeated measures ANOVA was used for statistical analysis. Results: No participant exhibited clinically significant radiologic or neurophysiological abnormalities. Post-collision MRI revealed cervical lordosis straightening in 75% of subjects, with no evidence of structural damage. EMG/NCV changes were statistically significant but within physiological norms. Pain reports decreased from 58.3% immediately post-collision to 25.0% after one week. Torque exceeded 30 N·m in 50% of participants, but all NIC values remained well below the 15 m²/s² injury threshold. Conclusions: Low-speed reverse collisions generate transient biomechanical loads and symptoms but do not result in clinically significant cervical spine injuries. Multimodal assessments, including high-resolution MRI, neurophysiological testing (EMG/NCS), pain scales, and kinematic indicators such as NIC and torque thresholds, highlight the need for objective evaluation to distinguish benign responses from true injury, aiding both clinical and medicolegal decisions.