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Finite element analysis of biom echanics for degenerative spin e with lumbar disc herniation a fter posterior discectomy, inser tion of interspinous device, or i ntervertebral cage Kuo-Yuan Huang(lecturer), Hsuan-Teh Hu, Li-Hsing Kao, Ching-Sung Kuo


Overview of report • Motives and Objectives • Methods of Research (Construction of Finite Element Model)

• Results • Conclusion


Motives and Objectives Motives 1.Degenerative disc diseases increase with aging and of ten cause pain from disc herniation. If conservative trea tments failed to improve the symptom, then the decom pression surgery will be considered further. 2.Traditional internal fixation systems with pedicle screw or cage would decrease the range of motion and even l ead to the degeneration of adjacent discs. 3.Interspinous process device can improve the compress ion of spinal nerve and afford additional effect of stabili ty of the treated segments.


Motives and Objectives

Objectives This research explored the treated effect of degenerative disc disease with disc herniati on after following treatments:

• Discectomy • Laminotomy • Laminectomy with or without

• DIAM (Dynamic Interspinous Assisted Motion) • Cage (PEEK)


Methods of Research (Construction of FE Model) L3~S1 segments of the spine with l angle = 30째 L3 L4 L5

Lumbosacral angle = 30 째

lumbosacra


Construction of FE Model Laminotomy/Laminectomy (partial/full removal)

(top half and lower quarter of lamina were removed)


Construction of FE Model (Cage) PEEK cage is implanted at Disc L4-5 Cage and treated disc

Cage and bone graft


Construction of FE Model (DIAM) • 按一下以編輯母片文字樣式 – 第二層 – 第三層 • 第四層 – 第五層

Coefficient of Surface Contact 0.5

Elastic Modulus (MPa)

Possion ratio ν

DIAM core

20

0.45

DIAM truss

5000

0.2


Methods of Research (material hypothesis) By weakening to 60% and 80% of original strength of annulus fibrosus to simulate various grades of degenerative disc disease


Methods of Research Abbreviation of Analysis Items No treatment

intact model Surgery

D80

Surgery (DIAM)

(weakened to 80%) Surgery (Cage) Surgery (DIAM + Cage) Surgery D60

Surgery (DIAM)

(weakened to 60%) Surgery (Cage) Surgery (DIAM + Cage)


Methods of Research (Preload and Boundary conditions) •

Boundary: Surface points

on Sacroiliac Joints are fixed

Preload: 150N on upper endplate of Vertebra L3


Methods of Research (Applied Moment in Extension/Flexion) 1Nm

1Nm

1Nm

1Nm

1Nm

1 Nm moment applied on each vertebra

Extension

1Nm

Flexion


Methods of Research (Applied Moment in Lateral Bending/Axial Rotation) 1Nm 1Nm 1Nm 1Nm

1Nm

1Nm

Lateral Bending

Axial Rotation


Abbreviation of used terms L3 IVD 34 L4 DIAM

FLEX for Flexion

IVD 45 L5

EXT for Extension

IVD 5S

LAT for Lateral Bending

ROT for Axial Rotation

SED for strain energy density


Results (relative rotation angles in EXT) IVD45*

In IVD45, different treatments

4 3.5 3 2.5 2 1.5 1 0.5 0

(degree)

decrease the relative rotation

angles. Lower adjacent segment (IVD5S)has more range of motion. 3.5

4

IVD34

(degree)

D80

D60

IVD5S

3

3

Surgery with DIAM

2.5 2

Surgery with Cage

1.5 1 0.5 0

3.5

After Surgery

No treatment

D80

D60

Surgery with DIAM & Cage

2.5 (degree)

4

No treatment

2 1.5 1 0.5 0

No treatment

D80

D60


Results (relative rotation angles in FLEX ) 9 8

IVD45*

In IVD45, whatever treatments 7

(degree)

6 5

are used, as in EXT, it would

2

(DIAM or CAGE Or DAIM+CAGE) reduce the range of motion. 9 8

IVD34

1 0 9

No treatment

D80

D60

D80

D60

IVD5S

7

5 4

Surgery with Cage

3 2

6 (degree)

Surgery with DIAM

6 (degree)

3

8

After Surgery

7

5 4 3 2

Surgery with DIAM & Cage

1 0

4

No treatment

D80

D60

1 0

No treatment


Results (relative rotation angles in LAT ) 4

In IVD45, only DIAM

3.5 3

DIAM. In IVD34 or IVD5S,

1.5

(degree)

differs with CAGE or CAGE+

2.5

3.5

IVD34

0

3.5

After Surgery

No treatment

D80

D60

D80

D60

IVD5S

3

2 1.5

Surgery with Cage

1 0.5 No treatment

D80

D60

Surgery with DIAM & Cage

2.5 (degree)

Surgery with DIAM

2.5 (degree)

0.5

4

3

0

2

1

little change between them. 4

IVD45*

2 1.5 1 0.5 0

No treatment


Results (relative rotation angles in ROT) 3

Upper or lower adjacent

2.5

IVD45*

segment, little change among (degree)

2

1.5

DIAM, CAGE, and DIAM+CAGE 1

0.5

, except in IVD45, for CAGE 3

2.5

(degree)

After Surgery

Surgery with DIAM

2 1.5

Surgery with Cage

1 0.5 0

Surgery with DIAM & Cage

No treatment

D80

D60

No treatment

D80

D60

D80

D60

3 2.5

IVD5S

2 (degree)

IVD34 or CAGE+DIAM case.

0

1.5 1 0.5 0

No treatment


Results (strain energy density in EXT)

In IVD45,DIAM has larger

0.03 0.02 (mJ/mm^3)

SED than CAGE or CAGE+

IVD45*

0.02

DIAM. IVD5S(Lower) has larger SED (degenerative trend)than IVD34(Upper). IVD34 0.03

Surgery with Cage

0.01 0.01

D60

Surgery with DIAM & Cage

No treatment

D80

D60

D80

D60

0.03 0.02 (mJ/mm^3)

(mJ/mm^3)

0.02

D80

0

IVD5S

Surgery with DIAM

No treatment

0.01

After Surgery

0.02

0

0.01

0.02 0.01 0.01 0

No treatment


Results (strain energy density in FLEX)

There are little changes DIAM+CAGE, inIVD34,

0.03 0.02 (mJ/mm^3)

among DIAM, CAGE, and

IVD45*

After Surgery

IVD34

0.01

Surgery with Cage

0.01

0

No treatment

D80

D60

Surgery with DIAM & Cage

No treatment

D80

D60

D80

D60

IVD5S 0.03

Surgery with DIAM

0.02

0

0.01 0

0.02 (mJ/mm^3)

(mJ/mm^3)

0.02

0.01 0

IVD45, and IVD5S. 0.03

0.02

0.02 0.01 0.01 0 0

No treatment


Results (strain energy density in LAT)

IVD5S(Lower) has larger SED

IVD45* 0.05 0.04

, DIAM has larger SED than

0.02

(mJ/mm^3)

than IVD34(Upper). In IVD45

0.01

CAGE or CAGE+DIAM. 0.05 0.04

0 0.05

IVD34

0.04

After Surgery

0.04

D80

D60

D80

D60

IVD5S

0.02

Surgery with Cage

0.02 0.01

0.03 (mJ/mm^3)

(mJ/mm^3)

0.03

0.03 0.02 0.02 0.01

0.01 0

No treatment

0.04 Surgery with DIAM

0.03

0

0.03

No treatment

D80

D60

Surgery with DIAM & Cage

0.01 0 0

No treatment


Results (strain energy density in ROT) IVD45*

As in LAT, in IVD45, DIAM

0.05 (mJ/mm^3)

has larger SED than CAGE

0.06 0.04 0.03

or CAGE+DIAM. IVD5S(lower)

0.02 0.01 0

No treatment

is more likely to degenerate than -0.01

0.06 0.05

0.03 0.02

Surgery with Cage

0.01

-0.01

D60

Surgery with DIAM & Cage

D80

D60

IVD5S

0.04 (mJ/mm^3)

(mJ/mm^3)

Surgery with DIAM

D80

0.05

After Surgery

0.04

No treatment

D60

0.06

IVD34 IVD34(upper).

0

D80

0.03 0.02 0.01 0 -0.01

No treatment


Results (max. von-Mises stress in EXT) IVD45*

The difference between 4

various treatments is small. IVD5S(lower) has larger

(MPa)

3

1

stress than IVD34(upper). 4 3.5

(MPa)

2.5

Surgery with Cage

2 1.5 1 0.5 No treatment

D80

D60

Surgery with DIAM & Cage

No treatment

D80

D60

IVD5S

Surgery with DIAM

3

0

0

After Surgery

IVD34

(MPa)

4.5

2

4.5 4 3.5 3 2.5 2 1.5 1 0.5 0

No treatment

D80

D60


Results (max. von-Mises stress in FLEX) IVD45*

D60 has less max. vonin IVD34 or IVD5S. 4.5

0

3 2.5 2 1.5 1 0.5 No treatment

No treatment

D80

D60

IVD5S

3.5 (MPa)

2

IVD34

4

0

3

1

D80

D60

After Surgery Surgery with DIAM Surgery with Cage Surgery with DIAM & Cage

(MPa)

5

4 (MPa)

Mises stress than D80

5

5 4.5 4 3.5 3 2.5 2 1.5 1 0.5 0

No treatment

D80

D60


Results (max. von-Mises stress in LAT)

In IVD45, DAIM has larger than CAGE or CAGE+

(MPa)

max. von-Mises stress DIAM. 7

(MPa)

4

Surgery with Cage

3 2 1 No treatment

D80

D60

Surgery with DIAM & Cage

No treatment

D80

D60

D80

D60

IVD5S 7

Surgery with DIAM

5

0

7 6 5 4 3 2 1 0

After Surgery

IVD34

6 5 (MPa)

6

IVD45*

4 3 2 1 0

No treatment


Results (max. von-Mises stress in ROT) 8

IVD5S has larger stress

7

IVD45*

6

value than IVD34, it means (MPa)

5 4 3

Lower adjacent disc is more 2

likely to degenerate than upper IVD34 adjacent disc. 8 7

Surgery with Cage

4 3 2

Surgery with DIAM & Cage

1 0

7

No treatment

D80

D60

No treatment

D80

D60

IVD5S

6 5 (MPa)

(MPa)

5

0 8

After Surgery Surgery with DIAM

6

1

4 3 2 1 0

No treatment

D80

D60


Conclusion (relative rotation angle) • DIAM decreases the movements of treated seg-ment in EXT/FL EX, while no significant changes in LAT/ROT. • CAGE remarkably decreases the movements of treated segmen

t in EXT/FLEX/LAT/ROT motions, and increases the change in a djacent segments.

• DIAM+CAGE decreases the movements of treated segment, wh ile there is little change in LAT/ROT, and adjacent segments nea r the intact model in EXT/FLEX .


Conclusion (Strain Energy Density) • DIAM apparently decreases the SED of treated segment i n EXT, while no significant changes in FLEX/LAT/ROT. • CAGE obviously decreases the SED of treated segment i n EXT/LAT/ROT motions, while little change in FLEX. • DIAM+CAGE evidently decrease the SED of treated segm ent in EXT/FLEX/LAT/ROT motions. • The SED of adjacent segments alter scarcely in above thr ee cases(DIAM/CAGE/DIAM+CAGE).


Conclusion (max. von-Mises stress) • Adjacent segments alter scarcely in DIAM/CAGE /DIAM +CAGE cases, with changes less than 2%. • DIAM decreases max. von-Mises stress in IVD45 in EXT/ FLEX, while little change in LAT/ROT. • CAGE decreases max. von-Mises stress in IVD45 more in EXT/LAT/ROT than DIAM. • DIAM+CAGE change more in IVD45 in EXT than only CA GE.


Thanks for Your Attention !!



2013 pasmiss meeting slides 102 7 31 ( revised )