scholarly journals Biaxial Tensile Testing and Constitutive Modeling of Human Supraspinatus Tendon

2012 ◽  
Vol 134 (2) ◽  
Author(s):  
Spencer E. Szczesny ◽  
John M. Peloquin ◽  
Daniel H. Cortes ◽  
Jennifer A. Kadlowec ◽  
Louis J. Soslowsky ◽  
...  
Keyword(s):  
Constitutive Model ◽  
Collagen Fiber ◽  
Supraspinatus Tendon ◽  
Angle Distribution ◽  
Fiber Angle ◽  
Biaxial Tensile ◽  
Uniaxial Testing ◽  
Biaxial Tensile Testing ◽  
Transverse Stresses ◽  
Fiber Organization

The heterogeneous composition and mechanical properties of the supraspinatus tendon offer an opportunity for studying the structure-function relationships of fibrous musculoskeletal connective tissues. Previous uniaxial testing has demonstrated a correlation between the collagen fiber angle distribution and tendon mechanics in response to tensile loading both parallel and transverse to the tendon longitudinal axis. However, the planar mechanics of the supraspinatus tendon may be more appropriately characterized through biaxial tensile testing, which avoids the limitation of nonphysiologic traction-free boundary conditions present during uniaxial testing. Combined with a structural constitutive model, biaxial testing can help identify the specific structural mechanisms underlying the tendon’s two-dimensional mechanical behavior. Therefore, the objective of this study was to evaluate the contribution of collagen fiber organization to the planar tensile mechanics of the human supraspinatus tendon by fitting biaxial tensile data with a structural constitutive model that incorporates a sample-specific angular distribution of nonlinear fibers. Regional samples were tested under several biaxial boundary conditions while simultaneously measuring the collagen fiber orientations via polarized light imaging. The histograms of fiber angles were fit with a von Mises probability distribution and input into a hyperelastic constitutive model incorporating the contributions of the uncrimped fibers. Samples with a wide fiber angle distribution produced greater transverse stresses than more highly aligned samples. The structural model fit the longitudinal stresses well (median R2 ≥ 0.96) and was validated by successfully predicting the stress response to a mechanical protocol not used for parameter estimation. The transverse stresses were fit less well with greater errors observed for less aligned samples. Sensitivity analyses and relatively affine fiber kinematics suggest that these errors are not due to inaccuracies in measuring the collagen fiber organization. More likely, additional strain energy terms representing fiber-fiber interactions are necessary to provide a closer approximation of the transverse stresses. Nevertheless, this approach demonstrated that the longitudinal tensile mechanics of the supraspinatus tendon are primarily dependent on the moduli, crimp, and angular distribution of its collagen fibers. These results add to the existing knowledge of structure-function relationships in fibrous musculoskeletal tissue, which is valuable for understanding the etiology of degenerative disease, developing effective tissue engineering design strategies, and predicting outcomes of tissue repair.

Continuity and Affine Fiber Kinematics in Biaxial Tension of the Supraspinatus Tendon

2011 ◽  
Author(s):  
Spencer E. Szczesny ◽  
John Peloquin ◽  
Sarah Ilkhani-Pour ◽  
Daniel H. Cortes ◽  
Jennifer A. Kadlowec ◽  
...  
Keyword(s):  
Boundary Condition ◽  
Material Properties ◽  
Biaxial Tension ◽  
Supraspinatus Tendon ◽  
Recent Analysis ◽  
Uniaxial Tensile ◽  
Angle Distribution ◽  
Fiber Angle ◽  
Uniaxial Tensile Testing

The human supraspinatus tendon (SST) exhibits strong heterogeneity in fiber alignment and material properties [1,2]. The relationship between fiber angle distribution and material properties has been previously described by a structurally based continuum model [3], which provided new quantitative structure-function relationships to explain the observed SST heterogeneity; however, in some locations and testing directions, the model predictions were not consistent with a continuum assumption [3]. More recent analysis of the change in fiber angle during loading showed that samples with less aligned fibers have less affine kinematics in uniaxial tensile loading [4]. That is, in uniaxial tensile testing, where the transverse edges freely contract, the fiber strain did not match the tissue strain. Because the SST is somewhat transversely constrained by surrounding rotator cuff structures in vivo and has distributed fibers to support multidirectional loading, the freely contracting edges of uniaxial tension may not appropriately constrain the tendon. Therefore, the objective of this study was to evaluate SST stress-strain behavior and affine deformation under biaxial tension. Specifically, if behaving as a continuum, we expected that applying a fixed boundary condition in the transverse direction would produce a higher apparent modulus, a smaller toe-region, and more affine fiber realignment than a free boundary condition.

scholarly journals Diet‐induced Vascular Remodeling Produces a Shift in Collagen Fiber Angle Distribution in a Mouse Model of Atherosclerosis

2015 ◽  
Vol 29 (S1) ◽  
Author(s):  
Shana Watson ◽  
Piaomu Liu ◽  
Edsel Pena ◽  
Michael Sutton ◽  
John Eberth ◽  
...  
Keyword(s):  
Mouse Model ◽  
Vascular Remodeling ◽  
Collagen Fiber ◽  
Angle Distribution ◽  
Fiber Angle

The Structure and Mechanical Properties of the Mitral Valve Leaflet-Strut Chordae Transition Zone

2004 ◽  
Vol 126 (2) ◽  
pp. 244-251 ◽  
Author(s):  
Ling Chen ◽  
Frank C-P. Yin, M.D., Ph.D. ◽  
Karen May-Newman, Ph.D.
Keyword(s):  
Mechanical Properties ◽  
Mitral Valve ◽  
Transition Zone ◽  
Collagen Fiber ◽  
Constitutive Law ◽  
Angle Distribution ◽  
Valve Leaflet ◽  
Biaxial Testing ◽  
Mitral Valve Leaflet ◽  
Fiber Angle

Biaxial testing, histological measurements and theoretical continuum mechanics modeling were employed to investigate the structure and mechanical properties of the mitral valve leaflet-strut chordae transition zone (LCT). The results showed that geometry changes and collagen fiber angle distribution contribute to variations in mechanical properties in the LCT zone. A simple three-coefficient exponential constitutive law was able to simulate the variation in stress-stretch behavior in the LCT zone by spatially varying a single coefficient and incorporating collagen fiber angle and degree of alignment. This quantitative information can greatly improve the predictions from biomechanical valve models by incorporating regional variations of structure and properties in the mitral leaflet-chordae tendineae system. These data provide the foundation for a computational model for studying stress distributions before and following chordal rupture, which may indicate the underlying reasons for the development of valve insufficiency in patients.

scholarly journals Comparison of Aortic Collagen Fiber Angle Distribution in Mouse Models of Atherosclerosis Using Second-Harmonic Generation (SHG) Microscopy

2016 ◽  
Vol 22 (1) ◽  
pp. 55-62 ◽  
Author(s):  
Shana R. Watson ◽  
Piaomu Liu ◽  
Edsel A. Peña ◽  
Michael A. Sutton ◽  
John F. Eberth ◽  
...  
Keyword(s):  
Second Harmonic Generation ◽  
Harmonic Generation ◽  
Fiber Orientation ◽  
Collagen Fiber ◽  
Second Harmonic ◽  
Western Diet ◽  
Chow Diet ◽  
Angle Distribution ◽  
Lesion Development ◽  
Fiber Angle

AbstractCharacterization of collagen fiber angle distribution throughout the blood vessel wall provides insight into the mechanical behavior of healthy and diseased arteries and their capacity to remodel. Atherosclerotic plaque contributes to the overall mechanical behavior, yet little is known experimentally about how collagen fiber orientation is influenced by atherogenesis. We hypothesized that atherosclerotic lesion development, and the factors contributing to lesion development, leads to a shift in collagen fiber angles within the aorta. Second-harmonic generation microscopy was used to visualize the three-dimensional organization of collagen throughout the aortic wall and to examine structural differences in mice maintained on high-fat Western diet versus age-matched chow diet mice in a model of atherosclerosis. Image analysis was performed on thoracic and abdominal sections of the aorta from each mouse to determine fiber orientation, with the circumferential (0°) and blood flow directions (axial ±90°) as the two reference points. All measurements were used in a multiple regression analysis to determine the factors having a significant influence on mean collagen fiber angle. We found that mean absolute angle of collagen fibers is 43° lower in Western diet mice compared with chow diet mice. Mice on a chow diet have a mean collagen fiber angle of ±63°, whereas mice on a Western diet have a more circumferential fiber orientation (~20°). This apparent shift in absolute angle coincides with the development of extensive aortic atherosclerosis, suggesting that atherosclerotic factors contribute to collagen fiber angle orientation.

scholarly journals Peripapillary and Posterior Scleral Mechanics—Part I: Development of an Anisotropic Hyperelastic Constitutive Model

2009 ◽  
Vol 131 (5) ◽  
Author(s):  
Michaël J. A. Girard ◽  
J. Crawford Downs ◽  
Claude F. Burgoyne ◽  
J.-K. Francis Suh
Keyword(s):  
Mechanical Properties ◽  
Finite Element ◽  
Optic Nerve ◽  
Constitutive Model ◽  
Optic Nerve Head ◽  
Collagen Fiber ◽  
Fiber Concentration ◽  
Fiber Alignment ◽  
Fiber Organization ◽  
Collagen Fiber Alignment

The sclera is the white outer shell and principal load-bearing tissue of the eye as it sustains the intraocular pressure. We have hypothesized that the mechanical properties of the posterior sclera play a significant role in and are altered by the development of glaucoma—an ocular disease manifested by structural damage to the optic nerve head. An anisotropic hyperelastic constitutive model is presented to simulate the mechanical behavior of the posterior sclera under acute elevations of intraocular pressure. The constitutive model is derived from fiber-reinforced composite theory, and incorporates stretch-induced stiffening of the reinforcing collagen fibers. Collagen fiber alignment was assumed to be multidirectional at local material points, confined within the plane tangent to the scleral surface, and described by the semicircular von Mises distribution. The introduction of a model parameter, namely, the fiber concentration factor, was used to control collagen fiber alignment along a preferred fiber orientation. To investigate the effects of scleral collagen fiber alignment on the overall behaviors of the posterior sclera and optic nerve head, finite element simulations of an idealized eye were performed. The four output quantities analyzed were the scleral canal expansion, the scleral canal twist, the posterior scleral canal deformation, and the posterior laminar deformation. A circumferential fiber organization in the sclera restrained scleral canal expansion but created posterior laminar deformation, whereas the opposite was observed with a meridional fiber organization. Additionally, the fiber concentration factor acted as an amplifying parameter on the considered outputs. The present model simulation suggests that the posterior sclera has a large impact on the overall behavior of the optic nerve head. It is therefore primordial to provide accurate mechanical properties for this tissue. In a companion paper (Girard, Downs, Bottlang, Burgoyne, and Suh, 2009, “Peripapillary and Posterior Scleral Mechanics—Part II: Experimental and Inverse Finite Element Characterization,” ASME J. Biomech. Eng., 131, p. 051012), we present a method to measure the 3D deformations of monkey posterior sclera and extract mechanical properties based on the proposed constitutive model with an inverse finite element method.

India Ink Pinprick Experiments on Surface Organization of Cricoarytenoid Joints

1986 ◽  
Vol 29 (4) ◽  
pp. 544-548 ◽  
Author(s):  
Joel C. Kahane ◽  
Alice R. Kahn
Keyword(s):  
Articular Cartilage ◽  
Collagen Fiber ◽  
Collagen Fibers ◽  
Articular Surfaces ◽  
India Ink ◽  
Age Related ◽  
Cricoarytenoid Joint ◽  
Mechanical Factors ◽  
Fiber Organization

Collagen fiber organization in the articular surfaces of the cricoarytenoid joint (CAJ) was studied using a pinpricking technique used in biomechanical research in orthopedics. Four male human formalin preserved specimens (3 months to 20 years) and 6 male freshly autopsied specimens (19 to 30 yrs) were studied. Specimens were dissected using the stereomicroscope. Distinctive patterns of articular cartilage slits reflect the orientation of collagen fibers in the cricoid and arytenoid articular surfaces. The orientation of the collagen fibers reinforces the articular surfaces along the principle path of CAJ motion. No age related differences were found. This suggests that the orientation of collagen fibers in the CAJ articular surfaces is prenatally determined rather than significantly influenced by postnatal mechanical factors.

On the implementation of FEA for the design and development of a new biaxial tensile test fixture for uniaxial testing machine: a validation for cruciform test specimens

2019 ◽  
Vol 41 (9) ◽  
Author(s):  
Luis Fernando Puente Medellín ◽  
Víctor Alfonso Ramírez Elías ◽  
Antonio de Jesús Balvantín García ◽  
Perla Iris Vázquez Gómez ◽  
José Angel Diosdado De la Peña
Keyword(s):  
Tensile Test ◽  
Testing Machine ◽  
Design And Development ◽  
Test Fixture ◽  
Biaxial Tensile Test ◽  
Biaxial Tensile ◽  
Uniaxial Testing

Matrix composition modulates vitamin D3’s effects on 3D collagen fiber organization by MCF10A cells

2021 ◽  
Author(s):  
Nafis Hasan ◽  
Yang Zhang ◽  
Irene Georgakoudi ◽  
Carlos Sonnenschein ◽  
Ana M. Soto
Keyword(s):  
Vitamin D3 ◽  
Collagen Fiber ◽  
Matrix Composition ◽  
3D Collagen ◽  
Mcf10a Cells ◽  
Fiber Organization
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