Table 1: Mechanical properties of materials.

MaterialYoung modulus 
(MPa)
Poisson coefficient Element typeNumber of elements

Outer vertebral endplates120000.3Tetrahedron3578
Intermediate vertebral endplates60000.3Tetrahedron2244
Centre of the vertebral endplates20000.3Tetrahedron831
Walls of the vertebral body120000.3Tetrahedron37205
Cancellous bone (inside vertebrae)1000.2Tetrahedron44954
Posterior vertebra30000.3Tetrahedron47134
Cartilage500.4Wedge3086
Annulus fibrosus4.20.45Hexahedron8288
Nucleus pulposus*Incompressible materialTetrahedron14410
Annulus fiber layers 13600.3Truss**592
Annulus fiber layers 24080.3Truss**592
Annulus fiber layers 34550.3Truss**592
Annulus fiber layers 45030.3Truss**592
Annulus fiber layers 55500.3Truss**296

LigamentYoung modulus 
(MPa)
Transition strain (%) Element typeNumber of elements

Anterior longitudinal ligament7.812.0Wedge**9046
20.0
Posterior longitudinal ligament10.011.0Wedge**3844
50.0
Ligamentum flavum15.06.2Tetrahedron**3042
19.0
Intertransverse ligament10.018.0Tetrahedron**6678
59.0
Capsular ligament7.525.0Membrane**3220
33.0
Interspinous ligament8.020.0Tetrahedron**2856
15.0
Supraspinous ligament10.014.0Tetrahedron**2657
12.0
Iliolumbar ligament7.812.0Wedge**816
20.0

* = 0.0343 MPa; = 0.1369 MPa. An elastic analysis with Young modulus of 1.0 MPa and Poisson ratio of 0.49 was carried out with similar results and a volume change less than 0.6%.
**Only tension.