Background
Methods
FE model of the lumbar spine and the posterior dynamic stabilization system
Material | Element type | Young’s modulus (MPa) | Poisson’s ratio | Area (mm2) |
---|---|---|---|---|
Bone
| ||||
Cortical | 8-node SOLID185 | Ex=11300 | ν xy=0.484 | - |
Ey=11300 | ν xz=0.203 | - | ||
Ez=22000 | ν yz=0.203 | |||
Gx=3800 | ||||
Gy=5400 | ||||
Gz=5400 | ||||
Cancellous | 8-node SOLID185 | Ex=140 | ν xy=0.45 | - |
Ey=140 | ν xz=0.315 | |||
Ez=200 | ν yz=0.315 | |||
Gx=48.3 | ||||
Gy=48.3 | ||||
Gz=48.3 | ||||
Posterior element | 8-nodeSOLID185 | 3500 | 0.25 | - |
Disc
| ||||
Nucleus pulposus | 8-node SOLID185 | 1.66 | 0.499 | - |
Ground Substance | 8-node SOLID185 | 5.36 | 0.45 | - |
d=1.12e-007 | C10=0.42 | C01=0.105 | ||
Annulus fibers
| 2-node LINK10 | |||
Outermost | 550 | - | 0.76 | |
Second | 495 | - | 0.5928 | |
Third | 412.5 | - | 0.4712 | |
Innermost | 357.5 | - | 0.3572 | |
Endplate
| 8-node SOLID185 | 24 | 0.4 | - |
Ligament
| 2-node LINK10 | |||
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 |
Decompression and stabilization of the lumbar spine
Components | Element type | Young's modulus (MPa) | Poisson's ratio |
---|---|---|---|
Titanium | 8-node SOLID185 | 110000 | 0.28 |
PCU spacer | 8-node SOLID185 | 68.4 | 0.4 |
PET cord | 8-node SOLID185 | 1500 | 0.4 |
Boundary and loading conditions
Results
Range of motion at the bridged level
L2/3 | L3/4 | |||||||
---|---|---|---|---|---|---|---|---|
ROM (Degree) | Flexion | Extension | Rotation | Bending | Flexion | Extension | Rotation | Bending |
INT
| 4.66 | 3.42 | 1.75 | 4.74 | 4.8 | 3.37 | 2.05 | 5.08 |
DEC
| 4.48 | 3.03 | 1.75 | 4.74 | 5.36 | 4.7 | 2.14 | 5.1 |
IntDyWL
| 5.88 | 3.65 | 1.83 | 5.4 | 0.93 | 2.68 | 1.8 | 2.75 |
DecDyWL
| 5.81 | 3.65 | 1.78 | 5.39 | 0.89 | 2.66 | 1.95 | 2.9 |
DecDyNL
| 5.52 | 3.77 | 1.76 | 5.28 | 1.97 | 2.16 | 2.13 | 3.28 |
DecDyNL0.8
| 5.52 | 3.7 | 1.76 | 5.19 | 1.97 | 2.47 | 2.12 | 3.43 |
Disc stress (KPa)
| ||||||||
INT
| 998.45 | 741 | 332 | 1316 | 944.39 | 687 | 372 | 1229.8 |
DEC
| 946.33 | 677.64 | 311.59 | 1318.4 | 1047.7 | 1446 | 438.63 | 1292.9 |
IntDyWL
| 1343 | 803.04 | 347 | 1588 | 440 | 592.36 | 522 | 793 |
DecDyWL
| 1323.2 | 792.27 | 337.29 | 1585.7 | 435.47 | 618.55 | 608.98 | 867.54 |
DecDyNL
| 1236.2 | 822.5 | 324.51 | 1531.1 | 558.48 | 579.08 | 397.79 | 780.8 |
DecDyNL0.8
| 1235.9 | 804.68 | 324.22 | 1500.2 | 558.36 | 607.8 | 404.13 | 859.36 |
Facet contact force (N)
| ||||||||
INT L
| 0.00 | 86.44 | 0.00 | 15.52 | 0.00 | 109.61 | 0.00 | 26.75 |
INT R
| 0.00 | 86.44 | 117.81 | 10.29 | 0.00 | 109.61 | 110.68 | 0.00 |
DEC L
| 0.00 | 67.85 | 0.00 | 14.15 | 0.00 | 77.13 | 0.00 | 32.87 |
DEC R
| 0.00 | 67.85 | 102.47 | 10.48 | 0.00 | 77.13 | 106.24 | 0.00 |
IntDyWL L
| 0.00 | 98.73 | 0.00 | 32.76 | 7.32 | 65.88 | 0.00 | 35.81 |
IntDyWL R
| 0.00 | 98.73 | 124.72 | 14.77 | 7.32 | 65.92 | 123.06 | 24.97 |
DecDyWL L
| 0.00 | 99.07 | 0.00 | 34.20 | 0.00 | 21.96 | 0.00 | 15.79 |
DecDyWL R
| 0.00 | 99.07 | 120.79 | 17.32 | 0.00 | 21.96 | 102.52 | 17.23 |
DecDyNL L
| 0.00 | 104.66 | 0.00 | 38.18 | 0.00 | 13.24 | 0.00 | 11.80 |
DecDyNL R
| 0.00 | 104.66 | 112.35 | 18.34 | 0.00 | 13.24 | 114.98 | 0.00 |
DecDyNL0.8 L
| 0.00 | 101.51 | 0.00 | 33.71 | 0.00 | 15.92 | 0.00 | 14.64 |
DecDyNL0.8 R
| 0.00 | 101.51 | 112.41 | 17.47 | 0.00 | 15.92 | 115.14 | 0.00 |