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. Author manuscript; available in PMC: 2017 Mar 21.
Published in final edited form as: J Biomech. 2016 Feb 8;49(5):780–785. doi: 10.1016/j.jbiomech.2016.01.035

Table 3.

Mean ± standard deviation (SD) of diagonal stiffness terms of disc specimens without posterior elements.

Test Series Frequency Preload
Frequency (Hz) 0.01 0.0115
Preload (N) mean 642±132 0 250 500
Fx/Dx (kN/mm) 0.17±0.07 0.06±0.01 0.11±0.01 0.15±0.02
Fy/Dy (kN/mm) 0.21±0.07 0.08±0.01 0.14±0.02 0.19±0.02
Fz/Dz (kN/mm) 3.3±0.7 0.41±0.08 1.7±0.1 2.5±0.2
Mx/Rx (Nm/deg) 2.8±2.2 0.92±0.11 1.9±0.6 2.7±0.8
Mz/Rz (Nm/deg) 2.4±1.0 0.85±0.14 1.7±0.2 2.2±0.2

Preload for specimens in the frequency test series was set to 0.4 MPa (mean = 642±132 N). Coordinate directions are x: posterior-anterior shear or lateral bending, y: lateral shear or flexion-extension and z: compression-tension or axial rotation.