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Updated: Oct 7, 2025
A Contusive Model of Unilateral Cervical Spinal Cord Injury Using the Infinite Horizon Impactor
Published on: July 24, 2012
Cervical spine injury response to direct rear head impact
Marie-Hélène Beauséjour1, Yvan Petit2, Éric Wagnac2
1Department of Mechanical Engineering, École de technologie supérieure, 1100 Notre-Dame Street West, H3C 1K3, Montreal, Quebec, Canada; Research Center, Hôpital du Sacré-Coeur de Montréal, 5400 Boulevard Gouin, H4J 1C5, Montreal, Quebec, Canada; International Laboratory on Spine Imaging and Biomechanics, France and Canada; Laboratoire de Biomécanique Appliquée-Université Gustave-Eiffel, Aix-Marseille Université, UMR T24, 51 boulevard Pierre Dramard, 13015 Marseille, France.
Background:
Direct rear head impact can occur during falls, road accidents, or sports accidents. They induce anterior shear, flexion and compression loads suspected to cause flexion-distraction injuries at the cervical spine. However, post-mortem human subject experiments mostly focus on sled impacts and not direct head impacts.
Methods:
Six male cadavers were subjected to a direct rear head impact of 3.5 to 5.5 m/s with a 40 kg impactor. The subjects were equipped with accelerometers at the forehead, mouth and sternum. High-speed cameras and stereography were used to track head displacements. Head range of motion in flexion-extension was measured before and after impact for four cadavers. The injuries were assessed from CT scan images and dissection.
Findings:
Maximum head rotation was between 43 degrees and 78 degrees, maximum cranial-caudal displacement between -12 mm and - 196 mm, and antero-posterior displacement between 90 mm and 139 mm during the impact. Four subjects had flexion-distraction injuries. Anterior vertebral osteophyte identification showed that fractures occurred at adjacent levels of osteophytic bridges. The other two subjects had no anterior osteophytes and suffered from C2 fracture, and one subject also had a C1-C2 subluxation. C6-C7 was the most frequently injured spinal level.
Interpretation:
Anterior vertebral osteophytes appear to influence the type and position of injuries. Osteophytes would seem to provide stability in flexion for the osteoarthritic cervical spine, but to also lead to stress concentration in levels adjacent to the osteophytes. Clinical management of patients presenting with osteophytes fracture should include neck immobilization and careful follow-up to ensure bone healing.
