Development of a multi-scale finite element model of the osteoporotic lumbar vertebral body for the investigation of apparent level vertebra mechanics and micro-level trabecular mechanics

McDonald, Katrina A.; Little, J. Paige; Pearcy, Mark J.; Adam, Clayton J.

doi:10.1016/j.medengphy.2010.04.006

Cited by 33 publications

(32 citation statements)

References 36 publications

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“…By combining single strut models, we were able to develop a cylindrical core lattice model for different age groups: young (<50 years), middle (50 through 75 years), and old (>75 years) ( Figure 1(a)). The geometries, which were the horizontal and vertical thicknesses ( ℎ and V ) and the horizontal and vertical lengths ( ℎ and V ) of each strut, are provided for each age group in Table 1 based on [20,21]. The elastic-perfectly plastic material properties of the struts were based on those of a previous study [20], in which Young's modulus was 8.0 GPa, the Poisson ratio was 0.3, and the yield stress was 64 MPa.…”

Section: Methodsmentioning

confidence: 99%

“…Lattice models have been proposed to simulate osteoporotic and normal bone through variation in trabecular thickness, spacing, or random material removal [15][16][17][18][19]. Since these studies only addressed the trabecular structure within a small region, a more recent study combined the lattice beam element model of the trabecular core with a thin layer of shell elements for the cortical part to make a whole vertebra model, and analyzed compressive strength, compressive stiffness, and tissue-level strain [20]. In this paper, finite element models of normal and various grades of osteoporotic lumbar vertebrae that incorporate the microscaled trabecular structure of lattice models and the cortical area of shell elements were developed.…”

Section: Introductionmentioning

confidence: 99%

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Stress Analysis of Osteoporotic Lumbar Vertebra Using Finite Element Model with Microscaled Beam-Shell Trabecular-Cortical Structure

Kim

2013

Journal of Applied Mathematics

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Osteoporosis is a disease in which low bone mass and microarchitectural deterioration of bone tissue lead to enhanced bone fragility and susceptibility to fracture. Due to the complex anatomy of the vertebral body, the difficulties associated with obtaining bones for in vitro experiments, and the limitations on the control of the experimental parameters, finite element models have been developed to analyze the biomechanical properties of the vertebral body. We developed finite element models of the L2 vertebra, which consisted of the endplates, the trabecular lattice, and the cortical shell, for three age-related grades (young, middle, and old) of osteoporosis. The compressive strength and stiffness results revealed that we had developed a valid model that was consistent with the results of previous experimental and computational studies. The von-Mises stress, which was assumed to predict the risk of a burst fracture, was also determined for the three age groups. The results showed that the von-Mises stress was substantially higher under relatively high levels of compressive loading, which suggests that patients with osteoporosis should be cautious of fracture risk even during daily activities.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Stress Analysis of Osteoporotic Lumbar Vertebra Using Finite Element Model with Microscaled Beam-Shell Trabecular-Cortical Structure

Kim

2013

Journal of Applied Mathematics

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“…The material properties of cancellous bone, including its apparent density, Young’s modulus and yield strength, as derived from the literature [20,21], were adopted. Young’s modulus of cancellous bone ranged from 60 MPa to 260 MPa with an increment of 40 MPa to simulate the 3 age groups [27,28] in this study. A failure strain of 60% was assigned to the cancellous bone to define the failure behavior during the simulation [29].…”

Section: Methodsmentioning

confidence: 99%

Effect of bone material properties on effective region in screw-bone model: an experimental and finite element study

et al. 2014

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BackgroundThere have been numerous studies conducted to investigate the pullout force of pedicle screws in bone with different material properties. However, fewer studies have investigated the region of effect (RoE), stress distribution and contour pattern of the cancellous bone surrounding the pedicle screw.MethodsScrew pullout experiments were performed from two different foams and the corresponding reaction force was documented for the validation of a computational pedicle screw-foam model based on finite element (FE) methods. After validation, pullout simulations were performed on screw-bone models, with different bone material properties to model three different age groups (<50, 50–75 and >75 years old). At maximum pullout force, the stress distribution and average magnitude of Von Mises stress were documented in the cancellous bone along the distance beyond the outer perimeter pedicle screw. The radius and volume of the RoE were predicted based on the stress distribution.ResultsThe screw pullout strengths and the load–displacement curves were comparable between the numerical simulation and experimental tests. The stress distribution of the simulated screw-bone vertebral unit showed that the radius and volume of the RoE varied with the bone material properties. The radii were 4.73 mm, 5.06 mm and 5.4 mm for bone properties of ages >75, 75 > ages >50 and ages <50 years old, respectively, and the corresponding volumes of the RoE were 6.67 mm3, 7.35 mm3 and 8.07 mm3, respectively.ConclusionsThis study demonstrated that there existed a circular effective region surrounding the pedicle screw for stabilization and that this region was sensitive to the bone material characteristics of cancellous bone. The proper amount of injection cement for augmentation could be estimated based on the RoE in the treatment of osteoporosis patients to avoid leakage in spine surgery.

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“…Inspection of (25) shows that the dynamical system in the modal space is described by a set of decoupled, linear, one-degree of freedom system with different relaxation times ⌧ j . Such a consideration shows that the continuous spectrum relaxation function of FHM may be properly discretized in a set of spectral rows corresponding to relaxation times ⌧ j , (j = 1, 2, .…”

Section: The Discrete Equivalent Representation Of Fhmmentioning

confidence: 99%

Power‐law hereditariness of hierarchical fractal bones

Deseri

Paola

Zingales

et al. 2013

Numer Methods Biomed Eng

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SUMMARYIn this paper the authors introduce a hierarchic fractal model to describe bone hereditariness. Indeed, experimental data of stress relaxation or creep functions obtained by compressive/tensile tests have been proved to be fit by power-law with real exponent 0   1. The rheological behavior of the material has therefore been obtained, using the Boltzmann-Volterra superposition principle, in terms of real order integrals and derivatives (fractional-order calculus). It is shown that the power-laws describing creep/relaxation of bone tissue may be obtained introducing a fractal description of bone cross-section and the Hausdorff dimension of the fractal geometry is then related to the exponent of the power-law. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 INTRODUCTIONMathematical models of material behavior are fundamental for optimization and for reliable design of engineered devices. Furthermore, the key issue is to be able to track down the multiscale behavior from the nano-to the macrolevel, with particular regard to biological and bioinspired materials.Indeed, the mechanical interactions among biomedical devices and biological tissues play a keyrole for the optimization of physiological functionality of such devices owing to the reduction of immunologic response. In this regard, it is clear that the detailed knowledge of the features of biological tissues at the different scales and their interactions with the devices is a crucial step to optimize the mechanical and physical response of the compound.Physical parameters of biological tissues usually investigated in scientific literature involve stiffness, strength, toughness, permeability, porosity, thermal conductivity among others [1,2,3].Besides these important features, mineralized bone tissues must provide load carrying capabilities and they exhibit a marked time-dependent behavior under applied loads. In this context, the term hereditariness is usually used in the sense that the actual response of bone material in terms of stress/displacement depends on previously applied stress/strain. This feature is macroscopically detectable by stress relaxation and creep observed in classical traction/compression mechanical tests. During a relaxation test, the imposed strain is held constant and a measure of the stress is monitored showing that it is a decreasing function of time; similarly, in a creep test an imposed constant stress is applied and a continuous monitoring of the strain is considered showing that it is an increasing function of time. Both these tests highlight the hereditariness feature of such material; the past undergone stress or strain history influence the future response of the specimen. A similar time-dependent behavior also arises in mineralized tissues as ligaments and tendons. Indeed the high stiffness (but highly brittleness) of the hydroxyapatite cryst...

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Development of a multi-scale finite element model of the osteoporotic lumbar vertebral body for the investigation of apparent level vertebra mechanics and micro-level trabecular mechanics

Cited by 33 publications

References 36 publications

Stress Analysis of Osteoporotic Lumbar Vertebra Using Finite Element Model with Microscaled Beam-Shell Trabecular-Cortical Structure

Stress Analysis of Osteoporotic Lumbar Vertebra Using Finite Element Model with Microscaled Beam-Shell Trabecular-Cortical Structure

Effect of bone material properties on effective region in screw-bone model: an experimental and finite element study

Power‐law hereditariness of hierarchical fractal bones

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