Biomechanics of Cervical Spine Ligaments

Abstract The purpose of the present study was to determine the geometrical and biomechanical properties of human cervical spine ligaments from the axis to the first thoracic level. A total of 33 human cadavers were used. Geometrical data included the length and cross-sectional area measurements. Biomechanical properties included force, deflection, stiffness, energy, stress, strain, and Young’s modulus of elasticity. These data were obtained for the anterior longitudinal ligament, posterior longitudinal ligament, joint capsules, ligamentum flavum, and interspinous ligament. Geometrical characteristics were determined using cryomicrotomy techniques and biomechanical properties were obtained using in situ failure tensile testing. Force-deformation responses of each ligament type and at each spinal level were normalized. The joint capsules and ligamentum flavum exhibited the highest area of cross-section (p < 0.005). The longitudinal ligaments responded with the highest length measurements. The strain parameters were higher for the ligaments of the posterior complex, i.e., interspinous ligament, joint capsules, and ligamentum flavum, than for the ligaments of the anterior complex, i.e., the anterior and posterior longitudinal ligaments. In contrast, the failure stress and Young’s modulus of elasticity were higher for the anterior and posterior longitudinal ligaments compared to the ligaments of the posterior complex. These findings delineate the relative contribution of the anterior and posterior ligaments in the human cervical spine.