Chondrocyte Death in Articular Cartilage Due to Excessive Mechanical Loading in the Axial and Transverse Directions

2002 ◽  
Author(s):  
Chih-Tung Chen ◽  
Peter A. Torzilli
Keyword(s):  
Articular Cartilage ◽  
Mechanical Loading ◽  
Impact Load ◽  
Impact Loads ◽  
Cyclic Loads ◽  
Matrix Degradation ◽  
Secondary Osteoarthritis ◽  
Load Duration ◽  
Chondrocyte Death ◽  
Traumatic Impact

Chondrocyte injury and death in articular cartilage can cause matrix degradation and is a risk factor for secondary osteoarthritis [1,3–5]. Chondrocyte death can occur due to excessive mechanical loading, such as with a single high traumatic impact load (≥20 MPa), repeated sub-impact loads (≥5 MPa), or extensive cyclic loads (≥1 MPa) [1–5]. Several recent studies have shown that chondrocyte death depends not only on the stress magnitude [2] but also on the stress rate [3], strain rate [5] and load duration [1–2].

Mechanical Loading Reduces Chondrocyte Death After Single Impact Trauma: Porcine Knee Model

2012 ◽  
Author(s):  
Lauren L. Vernon ◽  
David G. Wilensky ◽  
Chong Wang ◽  
Lee D. Kaplan ◽  
Chun-Yuh C. Huang
Keyword(s):  
Articular Cartilage ◽  
Mechanical Loading ◽  
Motor Vehicle ◽  
Degenerative Changes ◽  
Matrix Composition ◽  
Single Impact ◽  
Knee Model ◽  
Chondrocyte Death ◽  
Porcine Knee

Osteoarthritis often results from degenerative changes induced by trauma such as joint impact injuries sustained during athletics, combat, or motor vehicle accidents. Articular cartilage, avascular in nature, relies of synovial nutrition [1] and lacks sufficient regenerative capabilities [2]. Acute cartilage injuries have been shown to induce cell death [3, 4, 5], leading to reduced chondrocyte density and degenerative changes to the cartilage matrix composition; over time the tissue becomes compromised and loses its ability to maintain and restore itself. It has been demonstrated, that mechanical loading can affect local perfusion and diffusion through the matrix thereby altering the flow of nutrients and metabolites [2, 6]. Furthermore, mechanical loading modulates the chondrocyte biosynthesis of extracellular matrix that is required in the cartilage repair process. In this study, a two part in-vitro porcine knee model was utilized to investigate articular cartilage response immediately following a single impact injury under cyclic mechanical loading conditions.

Impact Testing of Concrete Using a Drop-Weight Impact Machine

2015 ◽  
Vol 1106 ◽  
pp. 225-228 ◽  
Author(s):  
Stanislav Rehacek ◽  
Petr Hunka ◽  
David Citek ◽  
Jiri Kolisko ◽  
Ivo Simunek
Keyword(s):  
Positive Impact ◽  
Impact Load ◽  
Impact Testing ◽  
Impact Loads ◽  
Test Machine ◽  
Impact Machine ◽  
Drop Weight ◽  
Weight Test ◽  
Load Tests ◽  
Drop Weight Test

Fibre-reinforced composite materials are becoming important in many areas of technological application. In addition to the static load, such structures may be stressed with short-term dynamic loads or even dynamic impact loads during their lifespan. Impact loading of structural components produces a complex process, where both the characteristics of the design itself and the material parameters influence the resultant behavior. It is clear that fibre reinforced concrete has a positive impact on increasing of the resistance to impact loads. Results of two different impact load tests carried out on drop-weight test machine are presented in this report.

Evaluation and prediction of material fatigue characteristics under impact loads: review and prospects

2022 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Xintian Liu ◽  
Que Wu ◽  
Shengchao Su ◽  
Yansong Wang
Keyword(s):  
Mechanical Properties ◽  
Design Methodology ◽  
Mechanical Performance ◽  
Impact Load ◽  
Impact Loads ◽  
Content Type ◽  
Material Fatigue ◽  
Mechanical Properties Of Materials ◽  
Fatigue Characteristics ◽  
Properties Of Materials

PurposeThe properties of materials under impact load are introduced in terms of metal, nonmetallic materials and composite materials. And the application of impact load research in biological fields is also mentioned. The current hot research topics and achievements in this field are summarized. In addition, some problems in theoretical modeling and testing of the mechanical properties of materials are discussed.Design/methodology/approachThe situation of materials under impact load is of great significance to show the mechanical performance. The performance of various materials under impact load is different, and there are many research methods. It is affected by some kinds of factors, such as the temperature, the gap and the speed of load.FindingsThe research on mechanical properties of materials under impact load has the characteristics as fellow. It is difficult to build the theoretical model, verify by experiment and analyze the data accumulation.Originality/valueThis review provides a reference for further study of material properties.

scholarly journals Wnt/β-catenin signaling contributes to articular cartilage homeostasis through lubricin induction in the superficial zone

2019 ◽  
Vol 21 (1) ◽  
Author(s):  
Fengjun Xuan ◽  
Fumiko Yano ◽  
Daisuke Mori ◽  
Ryota Chijimatsu ◽  
Yuji Maenohara ◽  
...  
Keyword(s):  
Articular Cartilage ◽  
Mechanical Loading ◽  
Cartilage Degeneration ◽  
Mrna Levels ◽  
Superficial Zone ◽  
Gain Of Function ◽  
Wnt Ligands ◽  
Signaling Activation ◽  
Signaling Activity

Abstract Background Both loss- and gain-of-function of Wnt/β-catenin signaling in chondrocytes result in exacerbation of osteoarthritis (OA). Here, we examined the activity and roles of Wnt/β-catenin signaling in the superficial zone (SFZ) of articular cartilage. Methods Wnt/β-catenin signaling activity was analyzed using TOPGAL mice. We generated Prg4-CreERT2;Ctnnb1fl/fl and Prg4-CreERT2;Ctnnb1-ex3fl/wt mice for loss- and gain-of-function, respectively, of Wnt/β-catenin signaling in the SFZ. Regulation of Prg4 expression by Wnt/β-catenin signaling was examined in vitro, as were upstream and downstream factors of Wnt/β-catenin signaling in SFZ cells. Results Wnt/β-catenin signaling activity, as determined by the TOPGAL reporter, was high specifically in the SFZ of mouse adult articular cartilage, where Prg4 is abundantly expressed. In SFZ-specific β-catenin-knockout mice, OA development was significantly accelerated, which was accompanied by decreased Prg4 expression and SFZ destruction. In contrast, Prg4 expression was enhanced and cartilage degeneration was suppressed in SFZ-specific β-catenin-stabilized mice. In primary SFZ cells, Prg4 expression was downregulated by β-catenin knockout, while it was upregulated by β-catenin stabilization by exon 3 deletion or treatment with CHIR99021. Among Wnt ligands, Wnt5a, Wnt5b, and Wnt9a were highly expressed in SFZ cells, and recombinant human WNT5A and WNT5B stimulated Prg4 expression. Mechanical loading upregulated expression of these ligands and further promoted Prg4 transcription. Moreover, mechanical loading and Wnt/β-catenin signaling activation increased mRNA levels of Creb1, a potent transcription factor for Prg4. Conclusions We demonstrated that Wnt/β-catenin signaling regulates Prg4 expression in the SFZ of mouse adult articular cartilage, which plays essential roles in the homeostasis of articular cartilage.

Mechanics Behavior Analysis on Laser Cladding under Repeated Impacting Load

2010 ◽  
Vol 154-155 ◽  
pp. 1100-1103
Author(s):  
Ru Shu Peng ◽  
De Wen Tang ◽  
Qiong Liu
Keyword(s):  
Behavior Analysis ◽  
Stress Wave ◽  
Laser Cladding ◽  
Impact Load ◽  
Joint Surface ◽  
Impact Loads ◽  
Repeated Impact ◽  
Hardness Change

On the property of repeated impact load, the attrition, hardening and plasticity warp of the laser cladding sampling were researched by using stress wave spread theory. Results show that under repeated impact loads, stress wave occurs on the metallurgical joint surface of the coat and the basis, forming stretch wave that causes coat slitting and angle splitting. The micro-pits failure and deep exfoliation occur on the coat surface because of the stress centralization. The accumulation of impact load energy cause hardness change and plasticity warp.

Cartilage (including meniscus)

2016 ◽  
Author(s):  
Peter M. van der Kraan ◽  
Esmeralda N. Blaney Davidson
Keyword(s):  
Growth Factors ◽  
Articular Cartilage ◽  
Chemical Composition ◽  
Cellular Differentiation ◽  
Matrix Composition ◽  
Current Status ◽  
Mechanical Stimuli ◽  
Matrix Degradation ◽  
Growth Factor Signalling

This chapter provides an overview of tissues unique to synovial joints, articular cartilage, and meniscus. The development and cellular and (bio)chemical composition are described, as well as the role of mechanical stimuli. In addition, the role of growth factors in cartilage and meniscus homeostasis, cellular differentiation, and chondrocyte hypertrophy are discussed. Furthermore, the involvement of aggrecanases and matrix metalloproteinases in cartilage and meniscus matrix degradation and osteoarthritis are described. Finally, the current status of repair of articular cartilage and meniscus is provided. This chapter reflects the changes in cellular differentiation, growth factor signalling, and altered matrix composition that contribute to osteoarthritis.

A Case for Avoiding Hydraulic Shock Suppressors (Snubbers) in the Vibratory Environments

2018 ◽  
Author(s):  
Kshitij P. Gawande ◽  
Phillip Wiseman ◽  
Alex Mayes
Keyword(s):  
Dynamic Load ◽  
Impact Load ◽  
Pressure Vessels ◽  
Mechanical Equipment ◽  
Internal Dynamic ◽  
Impact Loads ◽  
Hydraulic Shock ◽  
Dynamic Events ◽  
Piping Systems ◽  
The Impact

Whenever undesirable dynamic events occur within power plant, refinery, or process piping systems, specialty supports and restraints have the task of protecting the mechanical equipment and connecting piping from damaging loads and displacements. The array of components that may be affected include, but are not limited to, piping systems, pumps, valve assemblies, pressure vessels, steam generators, boilers, and heat exchangers. In particular, the dynamic events can be classified into two distinct types that originate from either internal events or external events. The internal dynamic load generating events include plant system start-up and shut-down, pressure surges or impacts from rapid valve closures such as steam and water hammer, boiler detonations, pipe rupture, and operating vibratory displacements that may be either low frequency or high frequency vibrations. The external dynamic load generating events include wind loads, earthquake, airplane impact to supporting structures and buildings, and explosions. Most of the aforementioned dynamic load generating events can be defined quite simply as impact loads, i.e., forces and moments that are applied over very short periods of time, for example, less than one second. While earthquake loads may be applied over a total time period of an hour or so, the peak loads and resulting displacements occur on a more sinusoidal basis of peak-to-peak amplitudes. One of the most common specialty restraint components utilized in the piping industry to absorb and transfer the dynamic load resulting from impact events is the hydraulic shock suppressor, otherwise known as the snubber. The snubber is a formidable solution to protecting plant piping systems and equipment from impact loading while not restricting the thermal displacements during routine operations. In the dynamic events that may be characterized by an impact type loading, snubbers provide an instantaneous, practically rigid, axial connection between the piping or other component to be secured and the surrounding structure whether it be concrete or steel (for example). In this way, the kinetic energy can be transmitted and harmlessly dissipated. In the vibratory environment, however, neither the impact load scenario nor the rapid translations are imposed upon snubbers, thereby presenting the competing intended application of the snubber to protect against impact loads versus, in many cases, the improper selection of the snubber to dampen vibratory (other than seismic) loads. The details of the hydraulic shock suppressor design are reviewed and discussed to exemplify why a case can and should be made against the use of snubbers in piping systems within an operating vibratory environment.

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