Multi-level Validation of a Male Neck Finite Element Model with Active Musculature.

Computational models of the human neck have been developed to human response in impact scenarios; however, the assessment and validation of such models is often limited to a small number of experimental data sets despite being used to evaluate the efficacy of safety systems and potential for injury risk in motor vehicle collisions. In the present study, a full neck model with active musculature was developed from previously validated motion segment models of the cervical spine. Tissue mechanical properties were implemented from experimental studies, and were not calibrated in any way. The neck model was assessed with experimental studies at three levels of increasing complexity: ligamentous cervical spine in axial rotation, axial tension, frontal impact, and rear impact; post mortem human subject rear sled impact; and human volunteer frontal and lateral sled tests using an open-loop muscle control strategy. The neck model demonstrated good correlation with the experiments ranging from quasi-static to dynamic, assessed using kinematics, kinetics and tissue level response. The contributions of soft tissues, neck curvature and muscle activation were associated with higher stiffness neck response, particularly for low severity frontal impact. Experiments presenting single-value data limited assessment of the model, while complete load history data and cross correlation enabled improved evaluation of the model over the full loading history. Tissue-level metrics exhibited higher variability and therefore lower correlation, also demonstrating a high dependence on the local tissue geometry. Thus, it is critical to assess models at the gross kinematic and the tissue levels.