Characterization of the Poroelastic Material Properties of Skeletal Repair Tissues Using Microindentation

2011 ◽  
Author(s):  
M. M. Sperry ◽  
L. N. M. Hayward ◽  
G. J. Miller ◽  
E. F. Morgan
Keyword(s):  
Material Properties ◽  
Repair Process ◽  
The United States ◽  
Fracture Site ◽  
Fe Model ◽  
Fracture Callus ◽  
Repetitive Injury ◽  
Poroelastic Material ◽  
Mechanical Factors ◽  
Callus Tissues

Nearly 10% of the approximately six million fractures that occur each year in the United States do not heal, causing lasting pain and repetitive injury [1]. Although the causes of poor healing are unknown in many cases, the sensitivity of the repair process to mechanical factors is well established. In an effort to understand how mechanical factors such as axial and shear micromotion at the fracture site affect healing, prior studies have sought to characterize the local mechanical environment using finite element (FE) analysis (e.g., [2,3]). However, a key set of inputs for the FE analyses is the distribution of material properties of the various tissues that comprise the fracture callus. Recent studies using nano- and microindentation have estimated these properties by approximating the tissues as linear elastic [4,5]. As a next step in this line of inquiry, the overall goal of this study was to estimate the linear, poroelastic material properties of callus tissues. The specific objectives were: 1) to develop an FE model for use in simulating microindentation experiments; and 2) to compare the results of the simulation to experimental microindentation data in order to derive the mechanical properties of the healing tissues.

Probabilistic Oblique Impact Analysis of Functionally Graded Plates – A Multivariate Adaptive Regression Splines Approach

2021 ◽  
Author(s):  
P. K. Karsh ◽  
Bindi Thakkar ◽  
R. R. Kumar ◽  
Vaishali ◽  
Sudip Dey
Keyword(s):  
Material Properties ◽  
Mass Density ◽  
Plate Thickness ◽  
Functionally Graded ◽  
Multivariate Adaptive Regression Splines ◽  
Low Velocity Impact ◽  
Fe Model ◽  
Low Velocity ◽  
Velocity Impact ◽  
Mars Model

Purpose: To investigate the probabilistic low-velocity impact of functionally graded (FG) plate using the MARS model, considering uncertain system parameters. Design/methodology/application: The distribution of various material properties throughout FG plate thickness is calculated using power law. For finite element (FE) formulation, isoparametric elements with eight nodes are considered, each component has five degrees of freedom. The combined effect of variability in material properties such as elastic modulus, modulus of rigidity, Poisson’s ratio, and mass density are considered. The surrogate model is validated with the FE model represented by the scatter plot and the probability density function (PDF) plot based on Monte Carlo simulation (MCS). Findings: The outcome of the degree of stochasticity, impact angle, impactor’s velocity, impactor’s mass density, and point of impact on the maximum value of contact force (CFmax ), plate deformation (PDmax), and impactor deformation (IDmax ) are determined. A convergence study is also performed to determine the optimal number of the constructed MARS model’s sample size. Originality/value: The results illustrate the significant effects of uncertain input parameters on FGM plates’ low-velocity impact responses by employing a surrogate-based MARS model.

Age Dependent and Anisotropic Material Properties of Immature Porcine Sclera

2013 ◽  
Author(s):  
Jami M. Saffioti ◽  
Brittany Coats
Keyword(s):  
Finite Element ◽  
Material Properties ◽  
Anisotropic Material ◽  
Computational Models ◽  
Fe Model ◽  
Ocular Tissues ◽  
Load Bearing ◽  
Anisotropic Properties ◽  
Age Dependent ◽  
Testing Protocols

Current finite element (FE) models of the pediatric eye are based on adult material properties [2,3]. To date, there are no data characterizing the age dependent material properties of ocular tissues. The sclera is a major load bearing tissue and an essential component to most computational models of the eye. In preparation for the development of a pediatric FE model, age-dependent and anisotropic properties of sclera were evaluated in newborn (3–5 days) and toddler (4 weeks) pigs. Data from this study will guide future testing protocols for human pediatric specimens.

Rupture of the Extensor Pollicis Longus Tendon in Undisplaced Colles’ Type of Fracture

HAND ◽  
1982 ◽  
Vol os-14 (1) ◽  
pp. 41-47 ◽  
Author(s):  
B. Helal ◽  
S. C. Chen ◽  
G. Iwegbu
Keyword(s):  
Fracture Site ◽  
Extensor Retinaculum ◽  
Fracture Callus ◽  
Extensor Pollicis Longus ◽  
Longus Tendon ◽  
Colles Fracture ◽  
Type Of Fracture ◽  
Extensor Pollicis Longus Tendon

There is a higher risk that the tendon of extensor pollicis longus will rupture in undisplaced Colles’ type of fracture than in those which are displaced. This difference in incidence is due to the integrity of the extensor retinaculum in undisplaced Colles’ type of fracture causing the tendon to be held tight against the fracture callus in the floor of the tunnel which may result in an attrition rupture. In the displaced Colles’ fracture the extensor retinaculum is torn from the bone and thus permits the tendon to escape from contact with the fracture site.

Modeling the Inflation Response of C57BL/6 Mouse Sclera

2011 ◽  
Author(s):  
Kristin M. Myers ◽  
Thao D. Nguyen
Keyword(s):  
Material Properties ◽  
Soft Tissues ◽  
Ganglion Cells ◽  
The United States ◽  
Small Rodent ◽  
Tissue Samples ◽  
Tissue Microstructure ◽  
Material Parameters ◽  
Meaningful Material

Small rodent models have become increasingly useful to investigate how the mechanical properties of soft tissues may influence disease development. These animal models allow access to aged, diseased, or genetically-altered tissue samples, and through comparisons with wild-type or normal tissue it can be explored how each of these variables influence tissue function. The challenges to deriving meaningful material parameters for these small tissue samples include designing physiologically-relevant mechanical testing protocols and interpreting the experimental load-displacement data in an appropriate constitutive framework to quantify material parameters. This study was motivated by determining the possible role of scleral material properties in the development of glaucomatous damage to the retinal ganglion cells (RGC). Glaucoma is one of the leading causes of blindness in the United States and in the world with an estimate of 60 million people affected by this year [1]. Through exploring mouse models, the overall goal of our work is to determine the role of scleral material properties and scleral tissue microstructure in the pathogenesis of glaucoma.

The Influence of Creep Strain on Crack Length Measurements Using the Potential Drop

2015 ◽  
Author(s):  
K. M. Tarnowski ◽  
C. M. Davies ◽  
K. M. Nikbin ◽  
D. W. Dean
Keyword(s):  
Stainless Steel ◽  
Crack Growth ◽  
Material Properties ◽  
Crack Extension ◽  
Electrical Potential ◽  
Creep Crack Growth ◽  
Potential Drop ◽  
Fe Model ◽  
Creep Properties ◽  
Length Measurements

One of the most common methods for estimating crack extension in the laboratory is electrical potential drop (PD). A key limitation of this technique is that it is sensitive to strains at the crack tip as well as crack extension. When producing J-R curves the onset of crack growth may be identified from a point of inflection on a plot of PD vs. CMOD. For creep crack growth (CCG) tests however, the effects of strain are often ignored. This paper investigates whether a similar method may be applied to CCG testing. A single CCG test was performed on type 316H stainless steel and a point of inflection, similar to that observed during J-R curve testing was identified. A finite element (FE) based approach was used to investigate this phenomenon further. A 3D sequentially-coupled structural-electrical FE model was used to reproduce the experimental PD vs. CMOD plot up to the point of inflection. The model was capable of predicting the general relationship between strain and PD. It predicted the magnitude of the change in PD to within 30%. A simplified 2D FE model was then used to perform a parametric study to investigate whether a similar trend may be expected for a range of materials. Power law tensile and creep properties were investigated with stress exponents of 1, 3 and 10. The results confirm that a point of inflection should be observable for the range of material properties considered.

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 A novel MRI compatible mouse fracture model to characterize and monitor bone regeneration and tissue composition

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Nina Schmitz ◽  
Melanie Timmen ◽  
Katharina Kostka ◽  
Verena Hoerr ◽  
Christian Schwarz ◽  
...  
Keyword(s):  
Fracture Healing ◽  
Bone Regeneration ◽  
Cell Attachment ◽  
Healing Process ◽  
Living Organism ◽  
Fracture Site ◽  
Tissue Composition ◽  
Metal Implants ◽  
Callus Tissues

Abstract Over the last years, murine in vivo magnetic resonance imaging (MRI) contributed to a new understanding of tissue composition, regeneration and diseases. Due to artefacts generated by the currently used metal implants, MRI is limited in fracture healing research so far. In this study, we investigated a novel MRI-compatible, ceramic intramedullary fracture implant during bone regeneration in mice. Three-point-bending revealed a higher stiffness of the ceramic material compared to the metal implants. Electron microscopy displayed a rough surface of the ceramic implant that was comparable to standard metal devices and allowed cell attachment and growth of osteoblastic cells. MicroCT-imaging illustrated the development of the callus around the fracture site indicating a regular progressing healing process when using the novel implant. In MRI, different callus tissues and the implant could clearly be distinguished from each other without any artefacts. Monitoring fracture healing using MRI-compatible implants will improve our knowledge of callus tissue regeneration by 3D insights longitudinal in the same living organism, which might also help to reduce the consumption of animals for future fracture healing studies, significantly. Finally, this study may be translated into clinical application to improve our knowledge about human bone regeneration.

A study of fracture callus material properties: Relationship to the torsional strength of bone

1990 ◽  
Vol 8 (6) ◽  
pp. 843-850 ◽  
Author(s):  
Mark D. Markel ◽  
Mark A. Wikenheiser ◽  
Edmund Y. S. Chao
Keyword(s):  
Material Properties ◽  
Fracture Callus ◽  
Torsional Strength

A 3d Histomorphometric Method for Analyses of Skeletal Tissue Mechanobiology

2007 ◽  
Author(s):  
Ryan E. Gleason ◽  
Kristy T. S. Palomares ◽  
Thomas A. Einhorn ◽  
Louis C. Gerstenfeld ◽  
Elise F. Morgan
Keyword(s):  
Healing Process ◽  
Fracture Site ◽  
Cartilage Tissue ◽  
In Vivo Model ◽  
Original Form ◽  
Mechanical Stimuli ◽  
Fracture Callus ◽  
Skeletal Tissue ◽  
Form And Function

Skeletal repair and regeneration involve a dynamic interplay of biological processes that result in spatially and temporally varying patterns of tissue formation and remodeling. For example, during bone fracture healing the cartilaginous callus that is formed initially in the fracture site is subsequently mineralized and remodeled to restore the original form and function to the injured bone. During much of this healing process, the fracture callus is comprised of a heterogeneous mixture of cartilage, fibrocartilage, multipotent mesenchymal tissue, and bone. Adding to this complexity, mechanical stimuli are known to influence the rate and type of tissues formed during skeletal healing [1]. Given the growing body of evidence that controlled mechanical stimulation may be used to enhance healing, it is of substantial interest to elucidate relationships between the distributions of local stresses and strains that develop within the healing region and the distribution of tissue types that form. While histomorphometry is a well established approach for characterizing the latter, it has historically been limited to analyses of a small number of two-dimensional sections of tissue. Such 2D sampling may be inadequate for quantitative characterization of the irregular geometry and heterogeneous composition of healing tissues. In this study, we report on a 3D histomorphometric method and apply this method to an in vivo model of skeletal repair [2] in which a bending stimulus delivered to a healing bone defect results in the formation of predominantly cartilage tissue, rather than bone.

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