A laboratory study examining biofidelity of a novel surrogate neck model in inverted head impact experiments

Contemporary headgear assessment techniques apply physical surrogate necks, borrowed from automotive crashworthiness mannequins, despite oft-cited limitations that broadly amount to doubts on their fidelity. Previously, we presented a prototype surrogate neck designed for assessing headgear in direct and oblique head impact leading to simultaneous neck flexion-extension and lateral bending. This study extends the past work by testing the neck in impact-induced axial compression described in previously published cadaver studies. Axial compression is an important impact mode for neck validation because of complicated neck mechanics and buckling that influence energy managed by the head. Inverted head first impacts were simulated with the head contacting a rigid impact surface at its vertex (0°), 15° anterior, and 15° posterior (-15°) in the sagittal plane. Neck forces and neck moments (at the lowest cervical level) were the bases on which buckling mechanics were studied as well as assessing biofidelity using CORAplus and a Bland-Altman analysis. Our neck exhibited buckling characteristics and statistical similarity to cadaveric data for axial force and sagittal moment at 0°. When the impact angle was -15° and 15°, the sagittal moment, time until peak, and time until buckling were statistically similar. CORAplus scores indicated that our neck had 'good biofidelity' across impact surface angles. Bland-Altman analysis of peaks complimented the CORAplus scores. These findings suggest the prototype neck exhibits buckling kinetics comparable to cadaver studies.