Surface strain and stress analysis of the mid-cervical vertebrae bony compartments: A biomechanical pilot study

OBJECTIVE: This study provides preliminary information on stress distribution over the cervical spine in static physiologic loading conditions with the strain-gage technique. Limited numbers of in vitro studies have been conducted to investigate strain and stress patterns on the bony structure of the functional cervical spine unit by various techniques. METHODS: In this pilot biomechanical study, strain gages were applied to the vertebral bodies and bilateral laminar sides of the C4, C5 and C6 levels in an occiput-T1 human cadaver model. Three different loading tests (axial compression, flexion and extension compressions) were conducted under static physiologic loading conditions. RESULTS: The anterior vertebral body experienced compressive stress with axial compressive and flexion loadings and tensile stress with extension loading. Laminar stresses were tensile pattern during axial compressive loading while tensile and compressive stresses were equal during flexion and extension loadings. CONCLUSION: The vertebral bodies adapt to each of the loadings with an expected compressive or tensile mechanic pattern as a one side fixed elastic beam in sagittal plane.