Intervertebral Disc Shape Variation and its Relationship to Degeneration Using Principal Components Analysis of a Population of MR Images

2012 ◽  
Author(s):  
John M. Peloquin ◽  
Jonathon H. Yoder ◽  
Nathan T. Jacobs ◽  
Sung M. Moon ◽  
Alexander C. Wright ◽  
...  
Keyword(s):  
Stress Distribution ◽  
Intervertebral Disc ◽  
Material Properties ◽  
Three Dimensional ◽  
Low Back ◽  
Shape Variation ◽  
Mr Images ◽  
Physiological Basis ◽  
Prevalent Disease ◽  
Components Analysis

Degeneration of the intervertebral disc (IVD) is implicated in low back pain, which is a costly and prevalent disease. Since the IVD is a mechanically active organ, it is important to consider its mechanical behavior as one factor in the degenerate pathology. Strain can be measured directly by imaging methods, but the stress distribution within the disc must be calculated. The stress distribution for a particular strain state is dependent on the IVD’s material properties and its geometry. While the material properties of the tissues comprising IVD have been extensively studied, its three-dimensional geometry remains incompletely characterized. Prior whole-disc models have been constructed from single IVDs. While this approach ensures that the geometry has a physiological basis, it is uncertain the degree to which results from a single IVD shape can be generalized to the entire population.

scholarly journals Computational Shape Models Characterize Shape Change of the Left Atrium in Atrial Fibrillation

2014 ◽  
Vol 8s1 ◽  
pp. CMC.S15710 ◽  
Author(s):  
Joshua Cates ◽  
Erik Bieging ◽  
Alan Morris ◽  
Gregory Gardner ◽  
Nazem Akoum ◽  
...  
Keyword(s):  
Atrial Fibrillation ◽  
Left Atrium ◽  
Shape Change ◽  
Three Dimensional ◽  
Shape Variation ◽  
Mr Images ◽  
Significant Group ◽  
Empirical Observation ◽  
Shape Models ◽  
Statistical Shape

Shape change of the left atrium (LA) and LA appendage in atrial fibrillation (AF) patients is hypothesized to be linked to AF pathology and to play a role in thrombogenesis; however, many aspects of shape variation in the heart are poorly understood. To date, studies of the LA shape in AF have been limited to empirical observation and summary metrics, such as volume and its likeness to a sphere. This paper describes a more comprehensive approach to the study of the LA shape through the use of computationally derived statistical shape models. We describe practical approaches that we have developed to extract shape parameters automatically from the three-dimensional MR images of the patient. From these images and our techniques, we can produce a more comprehensive description of LA geometric variability than that has been previously possible. We present the methodology and results from two examples of specific analyses using shape models: (1) we describe statistically significant group differences between the normal control and AF patient populations ( n = 137) and (2) we describe characteristic shapes of the LA appendage that are associated with the risk of thrombogenesis determined by transesophageal echocardiography ( n = 203).

Mechanics Characteristic Research of Human Lumbar Spine Based on the Changed Gradient for 3-D Printer

2014 ◽  
Vol 988 ◽  
pp. 449-452
Author(s):  
Bo Zhang ◽  
Heng Zhi Cai ◽  
Gang Zhou ◽  
Ya Jun Zhang ◽  
Jian Zhuang
Keyword(s):  
Lumbar Spine ◽  
Intervertebral Disc ◽  
Material Properties ◽  
Geometric Model ◽  
Three Dimensional ◽  
Artificial Joint ◽  
Human Lumbar Spine ◽  
Mechanics Characteristic ◽  
Spine Model ◽  
Gradient Change

According to the spinal anatomy data, three-dimensional geometric model of human lumbar spine L3-L5 segment is established in this paper. In the model, the vertebra is divided into cortical bone, cancellous bone, endplate and other structures. The connection between the vertebrae and intervertebral disc is simulated as contact joint. The material properties of lumbar parts of the structure are not the same, the elastic modulus is changing in the analysis. Based on the model, the deformation of the lumbar spine under different size of axial force and lateral torque is simulated. The simulation result shows the variation regularity of the deformation of vertebrae and intervertebral disc under the condition of different pressure. This research provides a quantitative reference for spinal bio-mechanics. The human spine model with a gradient change sets the foundation for processing field of artificial joint using the 3D printing technology.

Three-Dimensional Finite Element Analysis of Intervertebral Disc: Effects of In Vivo Loading Conditions and Endplate Calcification on Glucose Distributions

2010 ◽  
Author(s):  
Alicia R. Jackson ◽  
Chun-Yuh Huang ◽  
Wei Yong Gu
Keyword(s):  
Intervertebral Disc ◽  
Three Dimensional ◽  
The Body ◽  
Low Back ◽  
Element Analysis ◽  
Dimensional Finite Element ◽  
Three Dimensional Finite Element ◽  
Ivd Degeneration ◽  
In Vivo Loading

Degeneration of the intervertebral disc (IVD) of the spine is a common condition which has been implicated as a factor leading to low back pain. Poor nutritional supply is believed to be a primary contributor to IVD degeneration. Because the disc is the largest avascular structure in the body, cells must rely on transport of important nutrients, such as glucose and oxygen, from the surrounding vasculature in order to maintain cell viability in the disc tissue. Due to difficulty in obtaining data in vivo, theoretical modeling is a useful tool to supplement experimental results and predict in vivo conditions.

A Non-Linear Model to Describe the Material Properties of Single Lamellae in the Human Annulus Fibrosus

2011 ◽  
Author(s):  
Tina M. Nagel ◽  
Ramesh Raghupathy ◽  
Arin M. Ellingson ◽  
David J. Nuckley ◽  
Victor H. Barocas
Keyword(s):  
Low Back Pain ◽  
Back Pain ◽  
Intervertebral Disc ◽  
Linear Model ◽  
Material Properties ◽  
Annulus Fibrosus ◽  
Intervertebral Disc Degeneration ◽  
Low Back ◽  
Property Data ◽  
Fundamental Understanding

Roughly three out of four people experience low back pain [1]. Causes are generally unknown, but low back pain is often attributed to intervertebral disc degeneration. To understand low back pain better, much research has focused on a fundamental understanding of the disc. Physiologically analogous material properties may support improved modeling and understanding of disease progression. Unfortunately, to date, few material property data have been collected in a realistic environment.

scholarly journals Effect of Seepage on Change in Stress Distribution Scenario in Static and Seismic Behaviour of Earthen Dams

2018 ◽  
Vol 23 (1) ◽  
pp. 121-136 ◽  
Author(s):  
N. Nandi ◽  
Roy Chowdhury ◽  
S.C. Dutta
Keyword(s):  
Stress Distribution ◽  
Material Properties ◽  
Loading Condition ◽  
Seismic Analysis ◽  
Three Dimensional ◽  
Free Vibration Analysis ◽  
Mode Shapes ◽  
Earthen Dam ◽  
Element Analysis ◽  
Earthen Dams

AbstractThe present study makes an effort to understand the damage of earthen dams under static and seismic loading condition. To make the investigation more realistic, behaviour of earthen dams considering the occurrence of a phreatic line indicating the submerged zone due to seepage within the dam body is considered. In case of earthen dams, homogeneous or nonhomogeneous, the consideration of the occurrence of a phreatic line or seepage line through the dam body is an important part of the earthen dam design methodology. The impervious material properties in the submerged zone below the phreatic line due to seepage may differ a lot in magnitudes as compared to the value of the same materials lying above this line. Hence, to have the exact stress distribution scenarios within the earthen dam, the different material properties above and below the phreatic line are considered in this present study. The study is first carried out by two-dimensional as well as three-dimensional finite element analysis under static loading condition. The work is further extended to observe the effect of seepage due to the consideration of the phreatic line on dynamic characteristics of earthen dams. Free vibration analysis and seismic analysis based on the Complete Quadratic Combination (CQC) method by considering twodimensional and three-dimensional modeling are carried out to present the frequencies, mode shapes and the stress distribution pattern of the earthen dam.

Melatonin: Protection of the Intervertebral Disc

2019 ◽  
Vol 2 (3) ◽  
pp. 1-9
Author(s):  
Russel J Reiter ◽  
Sergio Rosales-Corral ◽  
Ramaswamy Sharma
Keyword(s):  
Intervertebral Disc ◽  
Molecular Mechanisms ◽  
Intervertebral Discs ◽  
Lumbar Pain ◽  
Low Back ◽  
Work Time ◽  
Protective Actions ◽  
Aging Populations ◽  
Definition Of ◽  
Endogenous Melatonin

     Low back pain (lumbar pain) due to injury of or damage to intervertebral discs is common in all societies.  The loss of work time as a result of this problem is massive.  Recent research suggests that melatonin may prevent or counteract intervertebral disc damage. This may be especially relevant in aging populations given that endogenous melatonin, in most individuals, dwindles with increasing age. The publications related to melatonin and its protection of the intervertebral disc are reviewed herein, including definition of some molecular mechanisms that account for melatonin’s protective actions. 

Pavement Damage Due to Conventional and New Generation of Wide-Base Super Single Tires

2005 ◽  
Vol 33 (4) ◽  
pp. 210-226 ◽  
Author(s):  
I. L. Al-Qadi ◽  
M. A. Elseifi ◽  
P. J. Yoo ◽  
I. Janajreh
Keyword(s):  
Carrying Capacity ◽  
Material Properties ◽  
Three Dimensional ◽  
Fe Analysis ◽  
Load Carrying Capacity ◽  
Inflation Pressure ◽  
3D Finite Element ◽  
Load Carrying ◽  
Pavement Damage ◽  
New Generation

Abstract The objective of this study was to quantify pavement damage due to a conventional (385/65R22.5) and a new generation of wide-base (445/50R22.5) tires using three-dimensional (3D) finite element (FE) analysis. The investigated new generation of wide-base tires has wider treads and greater load-carrying capacity than the conventional wide-base tire. In addition, the contact patch is less sensitive to loading and is especially designed to operate at 690kPa inflation pressure at 121km/hr speed for full load of 151kN tandem axle. The developed FE models simulated the tread sizes and applicable contact pressure for each tread and utilized laboratory-measured pavement material properties. In addition, the models were calibrated and properly validated using field-measured stresses and strains. Comparison was established between the two wide-base tire types and the dual-tire assembly. Results indicated that the 445/50R22.5 wide-base tire would cause more fatigue damage, approximately the same rutting damage and less surface-initiated top-down cracking than the conventional dual-tire assembly. On the other hand, the conventional 385/65R22.5 wide-base tire, which was introduced more than two decades ago, caused the most damage.

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