Table 1 Material properties used in the FE model

Bone

Ex = 11300

v xy = 0.484

[22]

Cortical

8-node SOLID185

Ey = 11300

v xz = 0.203

Ez = 22000

v yz = 0.203

Gx = 3800

Gy = 5400

Gz = 5400

Cancellous

8-node SOLID185

Ex = 140

v xy = 0.45

[22]

Ey = 140

v xz = 0.315

Ez = 200

v yz = 0.315

Gx = 48.3

Gy = 48.3

Gz = 48.3

Posterior bone

8-node SOLID185

3500

0.25

-

[22]

Disc

[22]

Nucleus pulposus

8-node FLUID80

1666.7

-

-

[22]

Ground Substance

8-node SOLID185

C₁₀ = 0.42

-

-

C₀₁ = 0.105

Annulus fibers

2-node LINK10

[23]

Outermost

550

-

0.76

Second

495

-

0.5923

Third

412.5

-

0.4712

Innermost

357.5

-

0.3572

Cartilaginous Endplates

8-node SOLID185

24

0.4

-

[22]

Ligaments

2-node LINK10

[25]

ALL

7.8

-

24

PLL

10

-

14.4

TL

10

-

3.6

LF

15

-

40

ISL

10

-

26

SSL

8

-

23

CL

7.5

-

30

Latero (PEEK)

8-node SOLID185

6500

0.2

Latero-plate (Titanium alloy)

8-node SOLID185

110000

0.3

SynFix-LR (PEEK)

8-node SOLID185

6500

0.2

Locking screw (Titanium alloy)

8-node SOLID185

110000

0.3

Stabilis (Titanium alloy)

8-node SOLID185

110000

0.3

SynCage-Open (Titanium alloy)

8-node SOLID185

110000

0.3

-

Pedicle screw (Titanium alloy)

8-node SOLID185

110000

0.3