On the anisotropy of skeletal muscle tissue under compression

Böl, Markus; Ehret, Alexander E.; Leichsenring, Kay; Weichert, Christine; Kruse, Rolf

doi:10.1016/j.actbio.2014.03.003

Cited by 84 publications

(53 citation statements)

References 71 publications

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“…This stiffness difference is microstructurally plausible since white matter consists primarily of myelinated axons [24], which act as a network of biopolymer filaments [25], while gray matter is largely composed of cell bodies. Contrary to the common belief that biofilaments are non-load-bearing under compression, recent studies have shown that biofilaments contribute notably to the compressive load carrying capacity of soft tissues [4]. Only one indentation study found opposite results and reported that white matter, with a modulus of 0.294kPa, was softer than gray matter, with a modulus of 0.454kPa, using atomic force microscopy on ultra thin rodent brain slices [9].…”

Section: Discussionmentioning

confidence: 99%

Mechanical properties of gray and white matter brain tissue by indentation

Budday

Nay

Rooij

et al. 2015

Journal of the Mechanical Behavior of Biomedical Materials

553

451

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The mammalian brain is composed of an outer layer of gray matter, consisting of cell bodies, dendrites, and unmyelinated axons, and an inner core of white matter, consisting primarily of myelinated axons. Recent evidence suggests that microstructural differences between gray and white matter play an important role during neurodevelopment. While brain tissue as a whole is rheologically well characterized, the individual features of gray and white matter remain poorly understood. Here we quantify the mechanical properties of gray and white matter using a robust, reliable, and repeatable method, flat-punch indentation. To systematically characterize gray and white matter moduli for varying indenter diameters, loading rates, holding times, post-mortem times, and locations we performed a series of n=192 indentation tests. We found that indenting thick, intact coronal slices eliminates the common challenges associated with small specimens: it naturally minimizes boundary effects, dehydration, swelling, and structural degradation. When kept intact and hydrated, brain slices maintained their mechanical characteristics with standard deviations as low as 5% throughout the entire testing period of five days post mortem. White matter, with an average modulus of 1.895kPa±0.592kPa, was on average 39% stiffer than gray matter, p<0.01, with an average modulus of 1.389kPa±0.289kPa, and displayed larger regional variations. It was also more viscous than gray matter and responded less rapidly to mechanical loading. Understanding the rheological differences between gray and white matter may have direct implications on diagnosing and understanding the mechanical environment in neurodevelopment and neurological disorders.

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Section: Discussionmentioning

confidence: 99%

Mechanical properties of gray and white matter brain tissue by indentation

Budday

Nay

Rooij

et al. 2015

Journal of the Mechanical Behavior of Biomedical Materials

553

451

View full text Add to dashboard Cite

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“…Four decades ago, pioneering experiments have characterized the ex vivo mechanics of explanted rabbit skin using uniaxial and biaxial testing [32, 53]. Other popular ex vivo setups for biological tissues include compression [8], shear [31], indentation [22], inflation [39], and bulge testing [54]. Recent attempts have focused on characterizing the mechanics of skin in vivo using either indentation [40] or aspiration [36].…”

Section: Motivationmentioning

confidence: 99%

Characterization of living skin using multi-view stereo and isogeometric analysis

et al. 2014

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Skin is our interface with the outside world. In its natural environment, it displays unique mechanical characteristics such as prestretch and growth. While there is a general agreement on the physiological importance of these features, they remain poorly characterized, mainly because they are difficult to access with standard laboratory techniques. Here we present a new, inexpensive technique to characterize living skin using multi-view stereo and isogeometric analysis. Based on easy-to-create hand-held camera images, we quantify prestretch, deformation, and growth in a controlled porcine model of chronic skin expansion. Over a period of five weeks, we gradually inflate an implanted tissue expander, take weekly photographs of the experimental scene, reconstruct the geometry from a tattooed surface grid, and create parametric representations of the skin surface. After five weeks of expansion, our method reveals an average area prestretch of 1.44, an average area stretch of 1.87, and an average area growth of 2.25. Area prestretch is maximal in the ventral region with 2.37, area stretch and area growth are maximal above the center of the expander with 4.05 and 4.81. Our study has immediate impact on understanding living skin to optimize treatment planning and decision making in plastic and reconstructive surgery. Beyond these direct implications, our experimental design has broad applications in clinical research and basic sciences: It serves as a simple, robust, low cost, easy-to-use tool to reconstruct living membranes, which are difficult to characterize in a conventional laboratory setup.

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“…This is derived from a need for a more complete understanding of the material behavior of these tissues, enabling simulations to accurately predict both local and global tissue function. While computational models of skeletal muscle have been developing since the introduction of the Hill model in 1938 (Hill, 1938), there have been relatively few studies of muscle tensile material properties at the tissue level (Abraham et al, 2012; Takaza et al, 2012), with the majority of studies evaluating compressive properties (Böl et al, 2014; Pietsch et al, 2014; Van Loocke et al, 2009, 2008, 2006). Studies of the structural response of individual muscle fibers (Meyer et al, 2011) and intact muscles (Calvo et al, 2010; Gras et al, 2012; Myers et al, 1998) are more prevalent.…”

Section: Introductionmentioning

confidence: 99%

“…Many recent investigations into skeletal muscle properties have focused on hyperelastic material properties (Böl et al, 2014; Calvo et al, 2010; Gras et al, 2012; D. A. Morrow et al, 2010; Pietsch et al, 2014; Takaza et al, 2012).…”

Section: Introductionmentioning

confidence: 99%

Skeletal muscle tensile strain dependence: Hyperviscoelastic nonlinearity

Wheatley

Morrow

Odegard

et al. 2016

Journal of the Mechanical Behavior of Biomedical Materials

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Introduction Computational modeling of skeletal muscle requires characterization at the tissue level. While most skeletal muscle studies focus on hyperelasticity, the goal of this study was to examine and model the nonlinear behavior of both time-independent and time-dependent properties of skeletal muscle as a function of strain. Materials and Methods Nine tibialis anterior muscles from New Zealand White rabbits were subject to five consecutive stress relaxation cycles of roughly 3% strain. Individual relaxation steps were fit with a three-term linear Prony series. Prony series coefficients and relaxation ratio were assessed for strain dependence using a general linear statistical model. A fully nonlinear constitutive model was employed to capture the strain dependence of both the viscoelastic and instantaneous components. Results Instantaneous modulus (p<0.0005) and mid-range relaxation (p<0.0005) increased significantly with strain level, while relaxation at longer time periods decreased with strain (p<0.0005). Time constants and overall relaxation ratio did not change with strain level (p>0.1). Additionally, the fully nonlinear hyperviscoelastic constitutive model provided an excellent fit to experimental data, while other models which included linear components failed to capture muscle function as accurately. Conclusions Material properties of skeletal muscle are strain-dependent at the tissue level. This strain dependence can be included in computational models of skeletal muscle performance with a fully nonlinear hyperviscoelastic model.

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On the anisotropy of skeletal muscle tissue under compression

Cited by 84 publications

References 71 publications

Mechanical properties of gray and white matter brain tissue by indentation

Mechanical properties of gray and white matter brain tissue by indentation

Characterization of living skin using multi-view stereo and isogeometric analysis

Skeletal muscle tensile strain dependence: Hyperviscoelastic nonlinearity

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