Finite Element Human Body Models to study Sex-differences in Whiplash Injury: Validation of VIVA+ passive response in rear-impact

Neck whiplash injury in rear impact is known to affect females more than males. However, there is a lack of female human body models (HBM) to study whiplash. This paper reports the low-speed passive head-neck kinematic response of a new lineup of models representing an average female and an average male, called VIVA+. The female model serves as the baseline model in the HBM lineup, and the male model is a morphed derivative from the base model. The head-neck kinematics of these two models were evaluated at multiple levels: from cervical spine functional spine unit (FSU) level to head-neck response to mini-sled rear impacts, and finally, whole-body response to rear-impacts. In general, the female FSU were more compliant in moment-rotation responses. In the head-neck mini-sled simulation, the female upper-cervical spine segments responded with more flexion than male segments, resulting in a more pronounced S-Curve formation. In the whole-body rear impact, although the head responded with rearward retraction and rotation and so also T1 with smaller magnitudes, these responses showed considerable differences when compared to the experiments. This could be attributed to the uncertainties in posture and anthropometrical characteristics of the post-mortem human subjects. These evaluations serve as the first step toward providing models to study sex-differences in whiplash injury risks.