Changes of the Cervical Spine in Response to Head-first Impact in Rugby: A Finite Element Analysis

Abstract

Objectives: To examine the effects of (1) trunk constraint and (2) the entry angle on the cervical spine in response to a headfirst impact. Materials: The AM50 Total HUman Model for Safety (THUMS ®) v4.02, pedestrian finite element model, was subjected to headfirst impacts. Methods: The impact speed was 3.2 m/s. The following patterns were simulated: entry angle (0° , 15°to the sagittal plane) and trunk constraint (constraint, unconstraint). Results: As a result of headfirst impact, the upper cervical spine was extended and the lower cervical spine was markedly flexed when the trunk was constrained. The mean stress applied to the cervical spine was significantly increased when the trunk was constrained, as indicated by the Mann-Whitney U test. Conclusions: In a headfirst impact, the mean stress on the cervical spine increases significantly when the trunk is constrained. In order to reduce the risk of cervical spine injuries, it is desirable not to bind with teammates before a headfirst impact.