Side Impact Causes Multiplanar Cervical Spine Injuries

Abstract

Side impact may cause neck and upper extremity pain, paresthesias, and impaired neck motion. No studies have quantified the cervical spine mechanical instability and injury threshold acceleration due to side impact. The goals of the present study were to identify and quantify cervical spine soft tissue injury and the injury threshold acceleration for side impact, and to compare these results with previous findings. Six human cervical spine specimens (C0-T1) underwent 3.5, 5, 6.5, and 8 g impacts. Pre- and postimpact flexibility tests were performed. Soft tissue injury was defined as a significant increase (p < 0.05) in the average intervertebral flexibility above the baseline 2 g impact. The injury threshold was the lowest T1 horizontal peak acceleration that caused the injury. The injury threshold acceleration was 6.5 g, with injuries occurring at C4-C5 through C7-T1 in flexion, axial rotation, or left lateral bending. After 8 g, three-plane injury was observed at C4-C5 and C6-C7, whereas two-plane injury occurred at C3-C4 in flexion and left lateral bending and at C5-C6 and C7-T1 in axial rotation and left lateral bending. Side impact caused multiplanar injuries at C3-C4 through C7-T1 and significantly greater injury at C6-C7, as compared with head-forward rear impact.