Nucleotomy Alters Mechanical Function Following Cyclic Loading and Unloaded Recovery of Human Discs

2012 ◽  
Author(s):  
Brent L. Showalter ◽  
Ian S. MacLean ◽  
Dawn M. Elliott ◽  
Neil R. Malhotra
Keyword(s):  
Cyclic Loading ◽  
Critical Role ◽  
Mechanical Effect ◽  
Low Back ◽  
Spinal Motion ◽  
Axial Cyclic Loading ◽  
Spinal Mechanics ◽  
Acute Changes ◽  
Cyclic Studies ◽  
Herniated Discs

The intervertebral disc plays a critical role in supporting loads, permitting spinal motion, and dissipating energy. Unfortunately, it is also commonly degenerated, resulting in altered spinal mechanics and low back pain. Nucleotomy is a common treatment for herniated discs and is also used experimentally to simulate degeneration.[1] The procedure, which involves a posterior annular incision and removal of a portion of the nucleus pulposus (NP), has also been shown to alter disc mechanics. These changes include acute changes of decreased NP pressure, decreased disc height, and increased neutral zones.[2, 3] Cyclic studies have shown that trans-endplate nucleotomy permanently alters creep mechanical properties of sheep discs.[4] However, the effects of annular nucleotomy on the cyclic properties of human discs have not yet been studied. This work studied the mechanical effect of annular nucleotomy on human discs subjected to physiological axial cyclic loading.

scholarly journals A Finite Element Study on Compressive Resistance Degradation of Square and Circular Steel Braces under Axial Cyclic Loading

2021 ◽  
Vol 11 (13) ◽  
pp. 6094
Author(s):  
Hubdar Hussain ◽  
Xiangyu Gao ◽  
Anqi Shi
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Cyclic Loading ◽  
Slenderness Ratio ◽  
Hysteretic Behavior ◽  
Element Analysis ◽  
Section Shape ◽  
Axial Cyclic Loading ◽  
Global Buckling ◽  
Parametric Studies

In this study, detailed finite element analysis was conducted to examine the seismic performance of square and circular hollow steel braces under axial cyclic loading. Finite element models of braces were constructed using ABAQUS finite element analysis (FEA) software and validated with experimental results from previous papers to expand the specimen’s matrix. The influences of cross-section shape, slenderness ratio, and width/diameter-to-thickness ratio on hysteretic behavior and compressive-tensile strength degradation were studied. Simulation results of parametric studies show that both square and circular hollow braces have a better cyclic performance with smaller slenderness and width/diameter-to-thickness ratios, and their compressive-tensile resistances ratio significantly decreases from cycle to cycle after the occurrence of the global buckling of braces.

Fatigue Failure Model for Composite Laminates under Multi-Axial Cyclic Loading

2000 ◽  
Vol 183-187 ◽  
pp. 945-950 ◽  
Author(s):  
Chong Soo Lee ◽  
W. Hwang ◽  
Hyun Chul Park ◽  
Kyung Seop Han
Keyword(s):  
Cyclic Loading ◽  
Fatigue Failure ◽  
Composite Laminates ◽  
Failure Model ◽  
Axial Cyclic Loading

scholarly journals Effective stress regime around a jacked steel pile during installation ageing and load testing in chalk

2018 ◽  
Vol 55 (11) ◽  
pp. 1577-1591 ◽  
Author(s):  
R.M. Buckley ◽  
R.J. Jardine ◽  
S. Kontoe ◽  
B.M. Lehane
Keyword(s):  
Cyclic Loading ◽  
Effective Stress ◽  
Test Site ◽  
Static Tension ◽  
Load Testing ◽  
Stress Regime ◽  
Effective Stresses ◽  
Axial Cyclic Loading ◽  
Tension Testing ◽  
Static And Cyclic Loading

This paper reports experiments with 102 mm diameter closed-ended instrumented Imperial College piles (ICPs) jacked into low- to medium-density chalk at a well-characterized UK test site. The “ICP” instruments allowed the effective stress regime surrounding the pile shaft to be tracked during pile installation, equalization periods of up to 2.5 months, and load testing under static tension and one-way axial cyclic loading. Installation resistances are shown to be dominated by the pile tip loads. Low installation shaft stresses and radial effective stresses were measured that correlated with local cone penetration test (CPT) tip resistances. Marked shaft total stress reductions and steep stress gradients are demonstrated in the vicinity of the pile tip. The local interface shaft effective stress paths developed during static and cyclic loading displayed trends that resemble those seen in comparable tests in sands. Shaft failure followed the Coulomb law and constrained interface dilation was apparent as the pile experienced drained loading to failure, although with a lesser degree of radial expansion than with sands. Radial effective stresses were also found to fall with time after installation, leading to reductions in shaft capacity as proven by subsequent static tension testing. The jacked, closed-ended, piles’ ageing trends contrast sharply with those found with open piles driven at the same site, indicating that ageing is affected by pile tip geometry and (or) installation method.

scholarly journals Reducing Lumbar Load with Active Corset

2018 ◽  
Vol 30 (5) ◽  
pp. 740-751 ◽  
Author(s):  
Michihiro Yoshida ◽  
Takayuki Tanaka ◽  
Yoshio Tsuchiya ◽  
Takashi Kusaka ◽  
◽  
...  
Keyword(s):  
Low Back Pain ◽  
Back Pain ◽  
Lumbar Spine ◽  
Mechanical Effect ◽  
Constant Force ◽  
Low Back ◽  
Bending Angle ◽  
Lumbar Load

This study describes the effect of Active Corset on the lumbar spine. Active Corset is assist tools used to prevent low back pain. It tightens the waist optimally according to the lumbar load during work. This study aimed to clarify the mechanical effect of tightening of the pelvis on lumbar joints and determine the mechanism leading to reduction of the lumbar load. Moreover, this study examined the phenomena commonly occurring among the subjects with reduced lumbar load by tightening of the pelvis. First, we will present some examples of currently used assist tools and demine the utility of the Active Corset among the various tools used. Next, the mechanism of the Active Corset will be described. Further, we will present a hypothesis about reducing the lumbar load by tightening the pelvis. After describing the change in the joint bending angle on tightening, we will describe reduction of burden from the antigravity torque around the lumbar joint. Finally, we will compare active tightening using Active Corset with tightening using a constant force and describe the advantage of active tightening.

The Role of Agarose Mechanical Response on the Matrix Synthesis of Nucleus Pulposus Cells: A Pilot Study

2009 ◽  
Author(s):  
Arzu Tasci ◽  
Ladina Ettinger ◽  
Stephen Ferguson ◽  
Philippe Büchler
Keyword(s):  
Cyclic Loading ◽  
Mechanical Response ◽  
Low Back ◽  
Limited Capacity ◽  
Nucleus Pulposus Cells ◽  
Matrix Synthesis ◽  
Biosynthetic Activity ◽  
The Matrix ◽  
Ivd Degeneration

Low back pain is the most common spinal disorder and its main cause is intervertebral disc (IVD) degeneration. IVD has a major role of withstanding loads generated in the spine during daily activities. However, it has a limited capacity for self-repair. Since it has an avascular structure, the pathways it uses for regeneration is quite complex and not yet well understood. The mechanical stimulation studies on the cell seeded constructs revealed that cells regulate their biosynthetic activity with cyclic loading [1,2]. The mechanical properties of the scaffold might play an important role in the transmission of mechanical signals to the embedded cells. The objective of this study is to investigate the effect of agarose concentration on the amount of extracellular matrix synthesis in IVD cell seeded constructs under static culture and cyclic loading conditions.

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