A HIGH ACCURACY CT BASED FEM MODEL OF THE LUMBAR SPINE TO DETERMINE ITS BIOMECHANICAL RESPONSE

Abstract Lumbar Lordotic correction (LLC), the gold standard treatment for Sagittal Spinal malalignment (SMA), and its effect on sagittal balance have been critically discussed in recent studies. This paper assesses the biomechanical response of the spinal components to LLC as an additional factor for the evaluation of LLC. Human lumbar spines (L2L5) were loaded with combined bending moments in Flexion (Flex)/Extension (Ex) or Lateral Bending (LatBend) and Axial Rotation (AxRot) in a physiological environment. We examined the dependency of AxRot range of motion (RoM) on the applied bending moment. The results were used to validate a Finite Element (FE) model of the lumbar spine. With this model, the biomechanical response of the intervertebral discs (IVD) and facet joints under daily motion was studied for different sagittal spinal alignment (SA) postures, simulated by a motion in Flex/Ex direction. Applied bending moments decreased AxRot RoM significantly (all P<0.001). A stronger decline of AxRot RoM for Ex than for Flex direction was observed (all P<0.0001). Our simulated results largely agreed with the experimental data (all R2>0.79). During daily motion, the IVD was loaded higher with increasing lumbar lordosis (LL) for all evaluated values at L2L3 and L3L4 and posterior Annulus Stress (AS) at L4L5 (all P<0.0476). The results of this study indicate that LLC with large extensions of LL may not always be advantageous regarding the biomechanical loading of the IVD. This finding may be used to improve the planning process of LLC treatments.

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A FEM Model Analysis of Human Lumbar Spine With Bi-Level Artificial Disc Replacement

Volume 2: Automotive Systems, Bioengineering and Biomedical Technology, Fluids Engineering, Maintenance Engineering and Non-Destructive Evaluation, and Nanotechnology ◽

10.1115/esda2006-95658 ◽

2006 ◽

Author(s):

A. Faizan ◽

A. Kiapour ◽

V. K. Goel ◽

A. Ivanov ◽

A. Biyani ◽

...

Keyword(s):

Finite Element ◽

Lumbar Spine ◽

Bending Moment ◽

Element Model ◽

Good Alternative ◽

Disc Replacement ◽

Artificial Disc ◽

Fem Model ◽

Artificial Disc Replacement ◽

Human Lumbar Spine

A finite element model of human lumbar spine (L3-S1 segment) was used to analyze biomechanical effects of the bi-level CHARITE artificial disc replacement (2LCHD) at L4-L5 and L5-S1 levels. The mechanical behavior and range of motion in implanted and intact models were compared using the finite element analyses and a hybrid loading protocol. In 2LCHD model the changes at L3-L4 level decreased by 25% also the model showed smooth changes in motion at implanted levels. In flexion there was an increase in facet loads at lower levels of 2LCHD however the bending moment in this model was less than intact model because of hybrid loading; in contrast, the facet loads in implanted model decreased in extension. It was observed that the bi-level disc replacement won’t affect much the kinematics of the spine and can be proposed as a good alternative for treatment in cases that disc degeneration occurs at more than one level of spine.

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Tangent Stiffness Matrix of Spatial Beam Element Considering Bend and Torsion Coupling Effect

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.1021.73 ◽

2014 ◽

Vol 1021 ◽

pp. 73-78

Author(s):

Liang Du ◽

Peng Lan ◽

Nian Li Lu

Keyword(s):

Stiffness Matrix ◽

Coupling Effect ◽

Beam Element ◽

High Accuracy ◽

Fem Model ◽

Tangent Stiffness ◽

Tangent Stiffness Matrix ◽

Spatial Beam ◽

Element Pattern ◽

Couple Effect

Based on the spatial beam-column differential equations, the slope deflection equations considering second-order and bend-torsion coupling effect are established. The additional moment caused by torsion and bend deflection are taken into account. Then the finite element pattern of spatial beam-column considering the couple effect of torsion and bend is given. The tangent stiffness matrix and relevant program for nonlinear analysis are further obtained. By the nonlinear calculation and stability analysis of single component which has high accuracy or precise solution, the precision of the FEM model given in this paper is verified by comparing the results with that given in references.

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A New 1,000 kV Electron Microscope

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100061318 ◽

1967 ◽

Vol 25 ◽

pp. 260-261

Author(s):

M. Nishigaki ◽

S. Katagiri ◽

H. Kimura ◽

B. Tadano

Keyword(s):

Electron Microscope ◽

High Voltage ◽

Basic Research ◽

Chromatic Aberration ◽

High Accuracy ◽

Biological Specimen ◽

Voltage Electron ◽

High Voltage Electron Microscope ◽

High Voltage Electron

The high voltage electron microscope has many advantageous features in comparison with the ordinary electron microscope. They are a higher penetrating efficiency of the electron, low chromatic aberration, high accuracy of the selected area diffraction and so on. Thus, the high voltage electron microscope becomes an indispensable instrument for the metallurgical, polymer and biological specimen studies. The application of the instrument involves today not only basic research but routine survey in the various fields. Particularly for the latter purpose, the performance, maintenance and reliability of the microscope should be same as those of commercial ones. The authors completed a 500 kV electron microscope in 1964 and a 1,000 kV one in 1966 taking these points into consideration. The construction of our 1,000 kV electron microscope is described below.

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Impairment Tutorial: Recurrent Radioculpathy: Recurrent Radioculpathy and Apportionment

Guides Newsletter ◽

10.1001/amaguidesnewsletters.2002.julaug03 ◽

2002 ◽

Vol 7 (4) ◽

pp. 8-10

Author(s):

Christopher R. Brigham ◽

Leon H. Ensalada

Keyword(s):

Lumbar Spine ◽

Range Of Motion ◽

Disk Herniation ◽

Fourth Edition ◽

Recurrent Injury ◽

Injury Model ◽

Whole Person ◽

Spinal Region

Abstract Recurrent radiculopathy is evaluated by a different approach in the AMA Guides to the Evaluation of Permanent Impairment (AMA Guides), Fifth Edition, compared to that in the Fourth Edition. The AMA Guides, Fifth Edition, specifies several occasions on which the range-of-motion (ROM), not the Diagnosis-related estimates (DRE) method, is used to rate spinal impairments. For example, the AMA Guides, Fifth Edition, clarifies that ROM is used only for radiculopathy caused by a recurrent injury, including when there is new (recurrent) disk herniation or a recurrent injury in the same spinal region. In the AMA Guides, Fourth Edition, radiculopathy was rated using the Injury Model, which is termed the DRE method in the Fifth Edition. Also, in the Fourth Edition, for the lumbar spine all radiculopathies resulted in the same impairment (10% whole person permanent impairment), based on that edition's philosophy that radiculopathy is not quantifiable and, once present, is permanent. A rating of recurrent radiculopathy suggests the presence of a previous impairment rating and may require apportionment, which is the process of allocating causation among two or more factors that caused or significantly contributed to an injury and resulting impairment. A case example shows the divergent results following evaluation using the Injury Model (Fourth Edition) and the ROM Method (Fifth Edition) and concludes that revisions to the latter for rating permanent impairments of the spine often will lead to different results compared to using the Fourth Edition.

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