Study design: Digitized measurements of the intervertebral motions using cervical cineradiographs of 10 volunteers during direct impacts applied to their faces.
Objectives: To clarify the cervical spine motion during direct face impact and postulate some mechanisms of neck injuries.
Summary of background data: Neck injury occurs mostly in traffic or falling accidents. Hyperextension of the neck is considered the most common mechanism of the injury because most victims have lacerations or contusions on their faces.
Methods: A low-level backward impact load was applied to 10 healthy male volunteers' faces at the forehead and maxilla via a strap using a free-falling small mass. Cervical vertebral motion was recorded by radiograph cineradiography during the impact.
Results: The upper cervical spine showed a flexion motion for both conditions. Consequently, the cervical spine had an S-shaped curvature similar to that in cervical retraction. Intervertebral motions of the cervical spine were evaluated using an radiograph frame taken at the maximum cervical retraction. For the forehead load, intervertebral motion at C1-C2 was flexion, and motions of the lower cervical spine were extension. For the maxilla load, intervertebral motions from occiput-C1 through C4-C5 were flexion. The inflection point of the curvature was influenced by the impact location.
Conclusion: We detected a flexion motion of the upper or middle cervical spine during direct face impact. In an actual accident, if the cervical spine is forced into similar motion, we speculate that neck injury would occur in this retraction-like curvature of the cervical spine.