Biofidelic whole cervical spine model with muscle force replication for whiplash simulation.

Whiplash has been simulated using volunteers, whole cadavers, mathematical models, anthropometric test dummies, and whole cervical spines. Many previous in vitro whiplash models lack dynamic biofidelity. The goals of this study were to (1) develop a new dynamic whole cervical spine whiplash model that will incorporate anterior, lateral and posterior muscle force replication, (2) evaluate its performance experimentally and (3) compare the results with in vivo data. To evaluate the new model, rear-impact whiplash simulations were performed using the incremental trauma approach at maximum measured T1 horizontal accelerations of 3.6 g, 4.7 g, 6.6 g, and 7.9 g. The kinematic response of the new model, e.g., peak head-T1 extension and peak intervertebral rotations, were compared with the corresponding in vivo data. The average peak head-T1 extension was within the in vivo corridor during the 3.6 g whiplash simulation (9.1 kph delta V). The peak in vivo intervertebral rotations obtained during a 4.6 g whiplash simulation of a young volunteer were within, or only marginally in excess of, the 95% confidence limits of the average peak intervertebral rotations measured during the 4.7 g whiplash simulation of the present study. Thus, the new whole cervical spine model with muscle force replication produced biofidelic dynamic responses to simulated whiplash. The new model is capable of generating important biomechanical data that may help improve our understanding of whiplash injuries and injury mechanisms.