Quantification of a rat tail vertebra model for trabecular bone adaptation studies

Guo, X. Edward; Eichler, Markus; Takai, Erica; Kim, Chi Hyun

doi:10.1016/s0021-9290(01)00212-3

Cited by 23 publications

(25 citation statements)

References 10 publications

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“…However, the bone chamber study examined loading of newly formed trabecular tissue, not adaptation of preexisting bone tissue that already exhibits substantial stiffness. Our tissue strains were larger than those found in a rat tail loading model [10]. Loads in the rat tail, however, are applied to the cancellous bone through the cortical shell of the vertebrae which dominates the mechanical performance of the rat vertebra, whereas loading from our device is applied directly to cancellous bone tissue after removal of the cortical shell.…”

Section: Discussionmentioning

confidence: 66%

The Effects of Loading on Cancellous Bone in the Rabbit

Meulen

Yang

Morgan

et al. 2009

Clinical Orthopaedics &Amp; Related Research

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Mechanical stimuli are critical to the growth, maintenance, and repair of the skeleton. The adaptation of bone to mechanical forces has primarily been studied in cortical bone. As a result, the mechanisms of bone adaptation to mechanical forces are not well-understood in cancellous bone. Clinically, however, diseases such as osteoporosis primarily affect cancellous tissue and mechanical solutions could counteract cancellous bone loss. We previously developed an in vivo model in the rabbit to study cancellous functional adaptation by applying well-controlled mechanical loads to cancellous sites. In the rabbit, in vivo loading of the lateral aspect of the distal femoral condyle simulated the in vivo bone-implant environment and enhanced bone mass. Using animal-specific computational models and further in vivo experiments we demonstrate here that the number of loading cycles and loading duration modulate the cancellous response by increasing bone volume fraction and thickening trabeculae to reduce the strains experienced in the bone tissue with loading and stiffen the tissue in the loading direction.

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Section: Discussionmentioning

confidence: 66%

The Effects of Loading on Cancellous Bone in the Rabbit

Meulen

Yang

Morgan

et al. 2009

Clinical Orthopaedics &Amp; Related Research

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“…The validity of this explanation is further reinforced when comparing this study with a study carried out by Kim et al (Kim, Takai et al 2003), who made similar correlations for trabecular bone but in a longitudinal fashion. Using the rat tail loading model (Guo, Eichler et al 2002), the authors divided the trabecular compartment of loaded rat vertebrae into proximal, central and distal regions and correlated bone formation indices (as determined by histology) with average tissue SED values (as computed from FE models). Results revealed that bone formation rates correlated with average tissue strain energy density (SED) after one and two weeks of loading, R 2 = 0.42 and 0.37, respectively.…”

Section: Discussionmentioning

confidence: 99%

Experimental and finite element analysis of the mouse caudal vertebrae loading model: prediction of cortical and trabecular bone adaptation

Webster

Wirth

Lenthe

et al. 2011

Biomech Model Mechanobiol

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In this study, we attempt to predict cortical and trabecular bone adaptation in the mouse caudal vertebrae loading model using knowledge of bone's local mechanical environment at the onset of loading. In a previous study, we demonstrated appreciable 25.9 and 11% increases in both trabecular and cortical bone volume density, respectively, when subjecting the fifth caudal vertebrae (C5) of C57BL/6 (B6) mice to an acute loading regime (amplitude of 8N, 3000 cycles, 10 Hz, 3 times a week for 4 weeks). We have also established a validated finite element (FE) model of the C5 vertebra using micro-computed tomography (micro-CT), which characterizes, in 3D, the micro-mechanical strains present in both cortical and trabecular compartments due to the applied loads. To investigate the relationship between load-induced bone adaptation and mechanical strains in-vivo and in-silico data sets were compared. Using data from the previous cross-sectional study, we divided cortical and trabecular compartments into 15 subregions and determined, for each region, a bone formation parameter ΔBV/BS (a cross-sectional measure of the bone volume added to cortical and trabecular surfaces following the described loading regime). Linear regression was then used to correlate mean regional values of ΔBV/BS with mean values of mechanical strains derived from the FE models which were similarly regionalized. The mechanical parameters investigated were strain energy density (SED), the orthogonal strains (e (x), e (y), e (z)) and the three shear strains (e (xy), e (yz), e (zx)). For cortical regions, regression analysis showed SED to correlate extremely well with ΔBV/BS (R (2) = 0.82) and e (z) (R (2) = 0.89). Furthermore, SED was found to predict expansion of the cortical shell correlating significantly with the regional percentage increases in cortical tissue volume (R (2) = 0.92), cortical marrow volume (R (2) = 0.91) and cortical thickness (R (2) = 0.56). For trabecular regions, FE parameters were found not to correlate with load-induced trabecular bone morphology. These results indicate that load-induced cortical morphology can be predicted from population data, whereas the prediction of trabecular morphology requires subject-specific micro- architecture.

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“…The method used for recording and evaluating the principal strain data generated by the finite-element models consists of averaging principal strain values of a node common to the neighboring elements, following similar methods used in the past (Lengsfeld et al, 1998;Remmler et al, 1998;Coleman et al, 2002;Guo et al, 2002). The strain gauge location on the virtual mandible is subject to a small but undetermined error with respect to the location of the strain gauge on the real specimen.…”

Section: Finite-element Analysismentioning

confidence: 99%

Finite‐element modeling of the anthropoid mandible: The effects of altered boundary conditions

2005

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Finite-element modeling provides a full-field method for describing the stress environment of the skull. The utility of finite-element models, however, remains uncertain given our ignorance of whether such models validly portray states of stress and strain. For example, the effects of boundary conditions that are chosen to represent the mechanical environment in vivo are largely unknown. We conducted an in vitro strain gauge experiment on a fresh, fully dentate adult mandible of Macaca fascicularis to model a simplified loading regime by finite-element analysis for purposes of model validation. Under various conditions of material and structural complexity, we constructed dentate and edentulous models to measure the effects of changing boundary conditions (force orientation and nodal constraints) on strain values predicted at the gauge location. Our results offer a prospective assessment of the difficulties encountered when attempting to validate finite-element models from in vivo strain data. Small errors in the direction of load application produce significant changes in predicted strains. An isotropic model, although convenient, shows poor agreement with experimental strains, while a heterogeneous orthotropic model predicts strains that are more congruent with these data. Most significantly, we find that an edentulous model performs better than a dentate one in recreating the experimental strains. While this result is undoubtedly tied to our failure to model the periodontal ligament, we interpret the finding to mean that in the absence of occlusal loads, teeth within alveoli do not contribute significantly to the structural stiffness of the mandible. © 2005 Wiley-Liss, Inc. Key words: mandible; computed tomography; image reconstruction; finite-element methodFinite-element analysis (FEA) is the method of choice for theoretical analysis of the mechanical behavior of complex shapes in biology. The approach of FEA approximates real geometry using a large number of smaller simple geometric elements (e.g., triangles, bricks, tetrahedrons). Since complex shapes defy simple mathematical solution (i.e., in terms of engineering formulas), FEA simplifies a problem by analyzing multiple simple elements of known shapes with established mathematical solutions. These multiple solutions are in the end combined together to depict states of stress and strain through the entire structure.The last half of the 20th century saw increasing interest in testing and analysis of bone biomechanics (Cowin, 2001), including increased use of finite-element (FE) methods. Many theoretical and experimental studies have sought to quantify the distribution of stresses and strain in the mandible (Knoell, 1977;Hylander, 1984;Bouvier

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Quantification of a rat tail vertebra model for trabecular bone adaptation studies

Cited by 23 publications

References 10 publications

The Effects of Loading on Cancellous Bone in the Rabbit

The Effects of Loading on Cancellous Bone in the Rabbit

Experimental and finite element analysis of the mouse caudal vertebrae loading model: prediction of cortical and trabecular bone adaptation

Finite‐element modeling of the anthropoid mandible: The effects of altered boundary conditions

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