Paulon, G. | Search bioRxiv

bioRxiv2023

Effects of Firefighter Helmets on Cervical Intervertebral Kinematics: An OpenSim-Based Biomechanical Study

The assessment of cervical intervertebral kinematics can serve as the basis for understanding any degenerative changes in the cervical spine due to the prolonged wear of a heavyweight, imbalanced firefighting helmet. Therefore, this study aimed to analyze cervical intervertebral kinematics using OpenSim musculoskeletal modeling platform in order to provide much-needed insights of how the inertial properties of firefighter helmet affect cervical spinal mobility. A total of 36 firefighters (18 males and 18 females) were recruited to perform static and dynamic neck flexion, extension, and left and right lateral bending tasks for three conditions: 1) no-helmet, 2) US-style helmet with a comparatively superior center of mass (COM), and 3) European-style helmet with relatively higher mass but an inferior COM. Three custom-made OpenSim head-neck models were created to calculate cervical intervertebral kinematics for each helmet condition. Results showed that the helmet use significantly (p<0.001) affects neck and cervical spinal kinematics. Especially, the superior COM placement in the US-style helmet, despite its lighter weight, caused more pronounced kinematic changes and quicker attainment of peak flexion and extension angles compared to the European-style helmet across all cervical joints. Moreover, results also revealed discrepancies between OpenSim-derived neck and cervical range-of-motion and those reported in previous in-vivo studies. In conclusion, the present study underscores the importance of designing firefighter helmets with a lower profile (less superior COM) to enhance neck range of motion and minimize potential neck injuries.

bioengineering↗

bioRxiv2023

Development and Validation of an MRI-Derived Head-Neck Finite Element Model

PurposeThis study aimed to develop and validate a magnetic resonance imaging (MRI)-based biofidelic head-neck finite element (FE) model comprised of scalp, skull, CSF, brain, dura mater, pia mater, cervical vertebrae, and discs, 14 ligaments, and 42 neck muscles. MethodsWe developed this model using head and neck MRI images of a healthy male participant and by implementing a novel meshing algorithm to create finer hexahedral mesh structures of the brain. The model was validated by replicating four experimental studies: NBDLs high acceleration profile, Itos frontal impact cervical vertebrae study, Alshareefs brain sonomicrometry study, and Nahums impact study. ResultsThe results showed reasonable geometrical fidelity. Our simulated brain displacement and cervical disc strain results were close to their experimental counterparts. The intracranial pressure and brain stress data of our head-only model (excluding neck structures and constraining the base of the skull) were similar to Nahums reported results. As neck structures were not considered in Nahums study, the FE results of our head-neck model showed slight discrepancies. Notably, the addition of neck structures (head-neck model) reduced brain stress values and uncovered the brains intracranial pressure dynamics, which the head-only model failed to capture. Nevertheless, the FE simulation results showed a good agreement (r > 0.97) between the kinematic responses of the head-neck model and NBDLs experimental results. ConclusionThe developed head-neck model can accurately replicate the experimental results and has the potential to be used as an efficient computational tool for brain and head injury biomechanics research. Statements and DeclarationsThis work was primarily supported by the U.S. Department of Homeland Security (70RSAT21CB0000023). The MRI data acquisition was supported by the Texas Tech Neuroimaging Center.

bioengineering↗