Load-sharing and kinematics of the human cervical spine under multi-axial transverse shear loading: combined experimental and computational investigation
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Date
2021-06
Authors
Whyte, Tom
Barker, Jeffrey
Cronin, Duane
Dumas, Genevieve
Nolte, Lutz-Peter
Cripton, Peter
Journal Title
Journal ISSN
Volume Title
Publisher
National Library of Medicine
Abstract
The cervical spine experiences shear forces during everyday activities and injurious events yet
there is a paucity of biomechanical data characterizing the cervical spine under shear loading.
This study aimed to 1) characterise load transmission paths and kinematics of the subaxial
cervical spine under shear loading, and 2) assess a contemporary finite element cervical spine
model using this data.
Subaxial functional spinal units (FSUs) were subjected to anterior, posterior and lateral shear
forces (200 N) applied with and without superimposed axial compression preload (200 N) while
monitoring spine kinematics. Load transmission paths were identified using strain gauges on the
anterior vertebral body and lateral masses and a disc pressure sensor.
Experimental conditions were simulated with cervical spine finite element model FSUs
(GHBMC M50 version 5.0). The mean kinematics, vertebral body strains and disc pressures
were compared to experimental results.
The shear force-displacement response typically demonstrated a toe region followed by a linear
response, with higher stiffness in the anterior shear direction relative to lateral and posterior
shear. Compressive axial preload decreased posterior and lateral shear stiffness and increased
anterior shear stiffness. Load transmission patterns and kinematics suggest the facet joints play a
key role in limiting anterior shear while the disc governs motion in posterior shear. The main
cervical spine shear responses and trends are faithfully predicted by the GHBMC finite element
cervical spine model.
These basic cervical spine biomechanics and the computational model can provide insight into
mechanisms for facet dislocation in high severity impacts, and tissue distraction in low severity
impacts.
Description
This preprint has not undergone peer review or any post-submission improvements or corrections. The Version of Record of this article is published in Journal of Biomechanical Engineering, and is available online at https://doi.org/10.1115/1.4050030
Keywords
cervical spine, biomechanics, ex vivo, shear, compression, load-sharing, kinematics