Preconditioning is Correlated With Altered Collagen Fiber Alignment in Ligament

2011 ◽  
Vol 133 (6) ◽  
Author(s):  
Kyle P. Quinn ◽  
Beth A. Winkelstein
Keyword(s):  
Collagen Fiber ◽  
Polarized Light ◽  
Peak Force ◽  
Principal Strain ◽  
Fiber Direction ◽  
Fiber Alignment ◽  
Tangent Stiffness ◽  
Vector Correlation ◽  
Fiber Organization ◽  
Collagen Fiber Alignment

Although the mechanical phenomena associated with preconditioning are well-established, the underlying mechanisms responsible for this behavior are still not fully understood. Using quantitative polarized light imaging, this study assessed whether preconditioning alters the collagen fiber alignment of ligament tissue, and determined whether changes in fiber organization are associated with the reduced force and stiffness observed during loading. Collagen fiber alignment maps of facet capsular ligaments (n = 8) were generated before and after 30 cycles of cyclic tensile loading, and alignment vectors were correlated between the maps to identify altered fiber organization. The change in peak force and tangent stiffness between the 1st and 30th cycle were determined from the force-displacement response, and the principal strain field of the capsular ligament after preconditioning was calculated from the fiber alignment images. The decreases in peak ligament force and tangent stiffness between the 1st and 30th cycles of preconditioning were significantly correlated (R ≥ 0.976, p < 0.0001) with the change in correlation of fiber alignment vectors between maps. Furthermore, the decrease in ligament force was correlated with a rotation of the average fiber direction toward the direction of loading (R = −0.730; p = 0.0396). Decreases in peak force during loading and changes in fiber alignment after loading were correlated (p ≤ 0.0157) with the average principal strain of the unloaded ligament after preconditioning. Through the use of a vector correlation algorithm, this study quantifies detectable changes to the internal microstructure of soft tissue produced by preconditioning and demonstrates that the reorganization of the capsular ligament’s collagen fiber network, in addition to the viscoelasticity of its components, contribute to how the mechanical properties of the tissue change during its preconditioning.

scholarly journals Quantitative mapping of collagen fiber alignment in thick tissue samples using transmission polarized-light microscopy

2016 ◽  
Vol 21 (7) ◽  
pp. 071111 ◽  
Author(s):  
Dmitry D. Yakovlev ◽  
Marina E. Shvachkina ◽  
Maria M. Sherman ◽  
Andrey V. Spivak ◽  
Alexander B. Pravdin ◽  
...  
Keyword(s):  
Light Microscopy ◽  
Collagen Fiber ◽  
Polarized Light ◽  
Polarized Light Microscopy ◽  
Tissue Samples ◽  
Fiber Alignment ◽  
Quantitative Mapping ◽  
Collagen Fiber Alignment

Collagen Fiber Alignment and Maximum Principal Strain in the Glenohumeral Capsule Predict Location of Failure During Uniaxial Extension

2011 ◽  
Author(s):  
Kelvin Luu ◽  
Carrie A. Voycheck ◽  
Patrick J. McMahon ◽  
Richard E. Debski
Keyword(s):  
Collagen Fiber ◽  
Glenohumeral Joint ◽  
Uniaxial Extension ◽  
Principal Strain ◽  
Fiber Alignment ◽  
Glenohumeral Ligament ◽  
Maximum Principal Strain ◽  
Inferior Glenohumeral Ligament ◽  
Glenohumeral Capsule ◽  
Collagen Fiber Alignment

The glenohumeral joint is frequently dislocated causing injury to the glenohumeral capsule (axillary pouch (AP), anterior band of the inferior glenohumeral ligament (AB-IGHL), posterior band of the inferior glenohumeral ligament (PB-IGHL), posterior (Post), and anterosuperior region (AS)). [1, 2] The capsule is a passive stabilizer to the glenohumeral joint and primarily functions to resist dislocation during extreme ranges of motion. [3] When unloaded, the capsule consists of randomly oriented collagen fibers, which play a pertinent role in its function to resist loading in multiple directions. [4] The location of failure in only the axillary pouch has been shown to correspond with the highest degree of collagen fiber orientation and maximum principle strain just prior to failure. [4, 5] However, several discrepancies were found when comparing the collagen fiber alignment between the AB-IGHL, AP, and PB-IGHL. [3,6,7] Therefore, the objective was to determine the collagen fiber alignment and maximum principal strain in five regions of the capsule during uniaxial extension to failure and to determine if these parameters could predict the location of tissue failure. Since the capsule functions as a continuous sheet, we hypothesized that maximum principal strain and peak collagen fiber alignment would correspond with the location of tissue failure in all regions of the glenohumeral capsule.

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.

Effect of Preconditioning on Collagen Fiber Recruitment: Inhomogeneous Properties of Rat Supraspinatus Tendon

2010 ◽  
Author(s):  
Kristin S. Miller ◽  
Lena Edelstein ◽  
Louis J. Soslowsky
Keyword(s):  
Mechanical Properties ◽  
Collagen Fiber ◽  
Insertion Site ◽  
Supraspinatus Tendon ◽  
Fiber Alignment ◽  
Rigorous Evaluation ◽  
Structural Alterations ◽  
Testing Protocol ◽  
Inhomogeneous Properties ◽  
Collagen Fiber Alignment

Cyclic preconditioning is a commonly accepted initial component of any tendon testing protocol. Preconditioning provides tendons with a consistent “history” and stress-strain results become repeatable allowing for rigorous evaluation and comparison. While it is widely accepted that preconditioning is important, changes that occur during preconditioning are not well understood. Micro-structural alterations, such as re-arrangement of collagen fibers, is one proposed mechanism of preconditioning [1,4]. However, this mechanism has not been examined. Therefore, the objective of this study is to locally measure: 1) fiber re-alignment during preconditioning, stress relaxation and tensile testing and 2) corresponding mechanical properties, to address mechanisms of preconditioning as well as tissue nonlinearity and inhomogeneity in the rat supraspinatus tendon. We hypothesize that 1) fiber re-alignment will be greatest in the toe region, but will also occur during preconditioning and 2) mechanical properties and initial collagen fiber alignment will be greater in the midsubstance location of the tendon compared to the tendon-to-bone insertion site.

Collagen Fiber Re-Alignment and Mechanical Properties in a Mouse Supraspinatus Tendon Model: Examining Changes With Age and Location

2012 ◽  
Author(s):  
Kristin S. Miller ◽  
Brianne K. Connizzo ◽  
Elizabeth Feeney ◽  
Louis J. Soslowsky
Keyword(s):  
Mechanical Properties ◽  
Collagen Fiber ◽  
Mechanical Load ◽  
Mechanical Test ◽  
Insertion Site ◽  
Supraspinatus Tendon ◽  
Tissue Response ◽  
Mechanical Stimuli ◽  
Fiber Alignment ◽  
Collagen Fiber Alignment

One postulated mechanism of tendon structural response to mechanical load is collagen fiber re-alignment. Recently, where collagen fiber re-alignment occurs during a tensile mechanical test has been shown to vary by tendon age and location in a postnatal developmental mouse supraspinatus tendon (SST) model [1]. It is thought that as the tendon matures and its collagen fibril network, collagen cross-links and collagen-matrix interactions develop, its ability to respond quickly to mechanical stimuli hastens [1]. Additionally, the insertion site and midsubstance of postnatal SST may develop differently and at different rates, providing a potential explanation for differences in fiber re-alignment behaviors at the insertion site and midsubstance at postnatal developmental time points [1]. However, collagen fiber re-alignment behavior, in response to mechanical load at a mature age and in comparison to developmental ages, have not been examined. Therefore, the objectives of this study are to locally measure: 1) fiber re-alignment during preconditioning and tensile mechanical testing and 2) to compare local differences in collagen fiber alignment and corresponding mechanical properties to address tissue response to mechanical load in the mature and postnatal developmental mouse SST. We hypothesize that 1) 90 day tendons will demonstrate the largest shift in fiber re-alignment during preconditioning, but will also re-align during the toe- and linear-regions. Additionally, we hypothesize that 2) mechanical properties and initial collagen fiber alignment will be greater in the midsubstance of the tendon compared to the tendon-to-bone insertion site at 90 days, 3) that mechanical properties will increase with age, and that 4) collagen fiber organization at the insertion site will decrease with age.

scholarly journals Non-Destructive Reflectance Mapping of Collagen Fiber Alignment in Heart Valve Leaflets

2019 ◽  
Vol 47 (5) ◽  
pp. 1250-1264 ◽  
Author(s):  
Will Goth ◽  
Sam Potter ◽  
Alicia C. B. Allen ◽  
Janet Zoldan ◽  
Michael S. Sacks ◽  
...  
Keyword(s):  
Heart Valve ◽  
Collagen Fiber ◽  
Fiber Alignment ◽  
Non Destructive ◽  
Collagen Fiber Alignment

Altered collagen fiber kinematics define the onset of localized ligament damage during loading

2008 ◽  
Vol 105 (6) ◽  
pp. 1881-1888 ◽  
Author(s):  
Kyle P. Quinn ◽  
Beth A. Winkelstein
Keyword(s):  
Structural Damage ◽  
High Speed ◽  
Collagen Fiber ◽  
Methodological Approach ◽  
Polarized Light ◽  
Spatial Location ◽  
Ligament Injury ◽  
Fiber Direction ◽  
Initial Injury ◽  
Ultimate Failure

Detecting the initiation of mechanical injury to biological tissue, and not just its ultimate failure, is critical to a sensitive and specific characterization of tissue tolerance, development of quantitative relationships between macro- and microstructural tissue responses, and appropriate interpretation of physiological responses to loading. We have developed a novel methodological approach to detect the onset and spatial location of structural damage in collagenous soft tissue, before its visible rupture, via identification of atypical regional collagen fiber kinematics during loading. Our methods utilize high-speed quantitative polarized light imaging to identify the onset of tissue damage in ligament regions where mean collagen fiber rotation significantly deviates from its behavior during noninjurious loading. This technique was validated by its ability to predict the location of visible rupture ( P = 0.0009). This fiber rotation-based metric of damage identifies potential facet capsular ligament injury beginning well before rupture, at 51 ± 12% of the displacement required to produce tissue failure. Although traditional macroscale strain metrics fail to identify the location of microstructural damage, initial injury detection determined by altered fiber rotation was significantly correlated ( R = 0.757, P = 0.049) with tissue yield (defined by a decrease in stiffness), supporting the capabilities of this method. Damaged regions exhibited higher variance in fiber direction than undamaged regions ( P = 0.0412).

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