scholarly journals Comparison of biphasic material properties of equine articular cartilage from stress relaxation indentation tests with and without tension-compression nonlinearity

2018 ◽  
Vol 4 (1) ◽  
pp. 485-488
Author(s):  
Thomas Reuter ◽  
Christof Hurschler
Keyword(s):  
Articular Cartilage ◽  
Stress Relaxation ◽  
Material Properties ◽  
Collagen Matrix ◽  
Biomechanical Properties ◽  
Resolution Parameter ◽  
Marquardt Algorithm ◽  
Mesh Resolution ◽  
Indentation Tests ◽  
Order Of Magnitude

AbstractThe mechanical parameters of articular cartilage estimated from indentation tests depend on the constitutive model adopted to analyze the data. In this study, we present a 3D-FE-based method to determine the biomechanical properties of equine articular cartilage from stress relaxation indentation tests (ε = 6 %, t = 1000 s) whereby articular cartilage is modeled as a biphasic material without (BM) and with tension-compression nonlinearity (BMTCN). The FEmodel computation was optimized by exploiting the axial symmetry and mesh resolution. Parameter identification was executed with the Levenberg-Marquardt-algorithm. The R² of the fit results varies between 0.695 and 0.930 for the BMmodel and between 0.877 and 0.958 for the BMTCN-model. The differences of the R² occur from the more exact description of the initial stress relaxation behaviour by the fiber modulus from the BMTCN-model. The fiber modulus defines the collagen matrix of cartilage. Furthermore, for both models the determined values of Young’s modulus and permeability were in the same order of magnitude.

Comparison of biphasic material properties of equine articular cartilage estimated from stress relaxation and creep indentation tests

2021 ◽  
Vol 7 (2) ◽  
pp. 363-366
Author(s):  
Thomas Reuter ◽  
Christof Hurschler
Keyword(s):  
Articular Cartilage ◽  
Stress Relaxation ◽  
Material Properties ◽  
Soft Tissues ◽  
Sensitivity Analyses ◽  
Creep Model ◽  
Fe Model ◽  
Relaxation Model ◽  
Marquardt Algorithm ◽  
Indentation Tests

Abstract Mechanical parameters of hard and soft tissues are explicit markers for quantitative tissue characterization. In this study, we present a comparison of biphasic material properties of equine articular cartilage estimated from stress relaxation (ε = 6 %, t = 1000 s) and creep indentation tests (F = 0.1 N, t = 1000 s). A biphasic 3D-FE-based method is used to determine the biomechanical properties of equine articular cartilage. The FE-model computation was optimized by exploiting the axial symmetry and mesh resolution. Parameter identification was executed with the Levenberg- Marquardt-algorithm. Additionally, sensitivity analyses of the calculated biomechanical parameters were performed. Results show that the Young’s modulus E has the largest influence and the Poisson’s ratio of ν ≤ 0.1 is rather insensitive. The R² of the fit results varies between 0.882 and 0.974 (creep model) and between 0.695 and 0.930 (relaxation model). The averaged parameters E and k determined from the creep model yield higher values in comparison to the relaxation model. The differences can be traced back to the experimental settings and to the biphasic material model.

scholarly journals Biphasic parameter identification of 3D scaffold-free cartilage transplants (SFCT) from stress relaxation compression tests using an optimized 3D FE-based method with tension-compression nonlinearity

2021 ◽  
Vol 7 (2) ◽  
pp. 355-358
Author(s):  
Thomas Reuter ◽  
Igor Ponomarev
Keyword(s):  
Articular Cartilage ◽  
Stress Relaxation ◽  
Tissue Characterization ◽  
Soft Tissues ◽  
Biomechanical Properties ◽  
Cartilage Defects ◽  
Fe Model ◽  
Compression Tests ◽  
3D Scaffold ◽  
Mesh Resolution

Abstract Cartilage constructs produced by SFCTtechnology provide promising opportunities to restore cartilage defects. Mechanical parameters of soft tissues are explicit markers for quantitative tissue characterization. In this study, we present a biphasic 3D-FE-based method to determine the biomechanical properties of SFCT from stress relaxation compression tests (ε = 20 %, t = 3400 s) whereby cartilaginous tissue is modeled as a biphasic material with tension-compression nonlinearity (BMTCN). The FE-model computation was optimized by exploiting the axial symmetry and mesh resolution. The R² of the fit results varies between 0.970 and 0.983. The Young’s and fiber modulus determined from SFCT are 37-times and 5-times lower than from native articular cartilage, respectively. Permeability, on the other hand, is 11-times higher than from native articular cartilage.

scholarly journals In Situ Microindentation for Determining Local Subchondral Bone Compressive Modulus

2010 ◽  
Vol 132 (9) ◽  
Author(s):  
Mack G. Gardner-Morse ◽  
Nelson J. Tacy ◽  
Bruce D. Beynnon ◽  
Maria L. Roemhildt
Keyword(s):  
Articular Cartilage ◽  
Subchondral Bone ◽  
Reference Values ◽  
Material Properties ◽  
Indentation Test ◽  
Lateral Compartment ◽  
Polyurethane Foams ◽  
Compressive Modulus ◽  
Sprague Dawley ◽  
Indentation Tests

Alterations to joint tissues, including subchondral bone, occur with osteoarthritis. A microindentation technique was developed to determine the local compressive modulus of subchondral bone. This test, in conjunction with a cartilage indentation test at the same location, could evaluate changes of these material properties in both tissues. The accuracy of the technique was determined by applying it to materials of known moduli. The technique was then applied to rat tibial plateaus to characterize the local moduli of the subchondral bone. An established nanoindentation method was adopted to determine the modulus of subchondral bone following penetration of the overlying articular cartilage. Three cycles of repeated loadings were applied (2.452 N, 30 s hold). The slope of the load-displacement response during the unloading portion of the third cycle was used to measure the stiffness. Indentation tests were performed on two polyurethane foams and polymethyl-methacrylate for validation (n=15). Regression analysis was used to compare the moduli with reference values. Subchondral bone moduli of tibial plateaus from Sprague-Dawley rats (n=5) were measured for central and posterior locations of medial and lateral compartments. An analysis of variance was used to analyze the effects of compartment and test location. The measured moduli of the validation materials correlated with the reference values (R2=0.993, p=0.05). In rat tibial plateaus, the modulus of the posterior location was significantly greater than the center location (4.03±1.00 GPa and 3.35±1.16 GPa respectively, p=0.03). The medial compartment was not different from the lateral compartment. This method for measuring the subchondral bone in the same location as articular cartilage allows studies of the changes in these material properties with the onset and progression of osteoarthritis.

scholarly journals Bi-Component T2 Mapping Correlates with Articular Cartilage Material Properties

2020 ◽  
pp. 110215
Author(s):  
Matthew M. Grondin ◽  
Fang Liu ◽  
Michael F. Vignos ◽  
Alexey Samsonov ◽  
Wan-Ju Li ◽  
...  
Keyword(s):  
Articular Cartilage ◽  
Material Properties ◽  
T2 Mapping

scholarly journals A composite scaffold of Wharton’s jelly and chondroitin sulphate loaded with human umbilical cord mesenchymal stem cells repairs articular cartilage defects in rat knee

2021 ◽  
Vol 32 (4) ◽  
Author(s):  
Zhong Li ◽  
Yikang Bi ◽  
Qi Wu ◽  
Chao Chen ◽  
Lu Zhou ◽  
...  
Keyword(s):  
Stem Cells ◽  
Articular Cartilage ◽  
Composite Scaffold ◽  
Biomechanical Properties ◽  
Cartilage Defects ◽  
Human Umbilical Cord ◽  
Composite Scaffolds ◽  
Articular Cartilage Defects

AbstractTo evaluate the performance of a composite scaffold of Wharton’s jelly (WJ) and chondroitin sulfate (CS) and the effect of the composite scaffold loaded with human umbilical cord mesenchymal stem cells (hUCMSCs) in repairing articular cartilage defects, two experiments were carried out. The in vitro experiments involved identification of the hUCMSCs, construction of the biomimetic composite scaffolds by the physical and chemical crosslinking of WJ and CS, and testing of the biomechanical properties of both the composite scaffold and the WJ scaffold. In the in vivo experiments, composite scaffolds loaded with hUCMSCs and WJ scaffolds loaded with hUCMSCs were applied to repair articular cartilage defects in the rat knee. Moreover, their repair effects were evaluated by the unaided eye, histological observations, and the immunogenicity of scaffolds and hUCMSCs. We found that in vitro, the Young’s modulus of the composite scaffold (WJ-CS) was higher than that of the WJ scaffold. In vivo, the composite scaffold loaded with hUCMSCs repaired rat cartilage defects better than did the WJ scaffold loaded with hUCMSCs. Both the scaffold and hUCMSCs showed low immunogenicity. These results demonstrate that the in vitro construction of a human-derived WJ-CS composite scaffold enhances the biomechanical properties of WJ and that the repair of knee cartilage defects in rats is better with the composite scaffold than with the single WJ scaffold if the scaffold is loaded with hUCMSCs.

scholarly journals Ovariectomy alters the structural and biomechanical properties of ovine femoro-tibial articular cartilage and increases cartilage iNOS

2005 ◽  
Vol 13 (12) ◽  
pp. 1066-1075 ◽  
Author(s):  
M.A. Cake ◽  
R.C. Appleyard ◽  
R.A. Read ◽  
M.M. Smith ◽  
G.A.C. Murrell ◽  
...  
Keyword(s):  
Articular Cartilage ◽  
Biomechanical Properties

scholarly journals Material properties and effect of preconditioning of human sclera, optic nerve, and optic nerve sheath

2021 ◽  
Author(s):  
Joseph Park ◽  
Andrew Shin ◽  
Somaye Jafari ◽  
Joseph L. Demer
Keyword(s):  
Optic Nerve ◽  
Mechanical Behavior ◽  
Material Properties ◽  
Biomechanical Properties ◽  
Ocular Tissues ◽  
Tangent Moduli ◽  
Nonlinear Mechanical ◽  
Human Eyes ◽  
Range Of Variation ◽  
Great Stress

AbstractThe optic nerve (ON) is a recently recognized tractional load on the eye during larger horizontal eye rotations. In order to understand the mechanical behavior of the eye during adduction, it is necessary to characterize material properties of the sclera, ON, and in particular its sheath. We performed tensile loading of specimens taken from fresh postmortem human eyes to characterize the range of variation in their biomechanical properties and determine the effect of preconditioning. We fitted reduced polynomial hyperelastic models to represent the nonlinear tensile behavior of the anterior, equatorial, posterior, and peripapillary sclera, as well as the ON and its sheath. For comparison, we analyzed tangent moduli in low and high strain regions to represent stiffness. Scleral stiffness generally decreased from anterior to posterior ocular regions. The ON had the lowest tangent modulus, but was surrounded by a much stiffer sheath. The low-strain hyperelastic behaviors of adjacent anatomical regions of the ON, ON sheath, and posterior sclera were similar as appropriate to avoid discontinuities at their boundaries. Regional stiffnesses within individual eyes were moderately correlated, implying that mechanical properties in one region of an eye do not reliably reflect properties of another region of that eye, and that potentially pathological combinations could occur in an eye if regional properties are discrepant. Preconditioning modestly stiffened ocular tissues, except peripapillary sclera that softened. The nonlinear mechanical behavior of posterior ocular tissues permits their stresses to match closely at low strains, although progressively increasing strain causes particularly great stress in the peripapillary region.

scholarly journals Variability of Mechanical Properties of Collagen Membranes used in Dentistry

2018 ◽  
Vol 55 (4) ◽  
pp. 488-493
Author(s):  
Loredana Santo ◽  
Fabrizio Quadrini ◽  
Denise Bellisario ◽  
Antonella Polimeni ◽  
Anna Santarsiero
Keyword(s):  
Stress Relaxation ◽  
Tensile Tests ◽  
Mechanical Analysis ◽  
Mechanical Tests ◽  
Static Behavior ◽  
Density Measurements ◽  
Dynamic Mechanical ◽  
Dependent Behavior ◽  
Order Of Magnitude ◽  
Collagen Membranes

The aim of this study is proposing a combination of measurements to assess the functional variability of collagen membranes used in Guided Bone Regeneration (GBR) and Guided Tissue Regeneration (GTR) techniques. As far as clinical applications are concerned, a proper qualification is critical when deciding, among commercially available collagen membranes, upon the most appropriate one for each specific clinical case. Two commercially available collagen membranes, namely Collprotect� and Jason�, were considered for the experimentation. After thickness and density measurements, the quasi-static behavior was studied for both membranes by means of conventional mechanical tests, i.e. tear and tensile tests, whereas their time-dependent behavior was evaluated by means of stress relaxation tests and dynamic mechanical analysis. Collagen membranes showed an elevated among samples variability. The variability within the same kind of membrane is of the same order of magnitude of the between membrane kinds variability. All the membranes showed strong time dependence both in stress relaxation and in dynamic mechanical tests. This fact should be taken under consideration for the membrane final application.

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