scholarly journals The Role of the Loading Condition in Predictions of Bone Adaptation in a Mouse Tibial Loading Model

2021 ◽  
Vol 9 ◽  
Author(s):  
Vee San Cheong ◽  
Visakan Kadirkamanathan ◽  
Enrico Dall’Ara
Keyword(s):  
Bone Remodeling ◽  
Mechanical Loading ◽  
Axial Load ◽  
Bone Adaptation ◽  
Combined Loading ◽  
Micro Ct ◽  
Loading Conditions ◽  
Physiological Loading ◽  
Physiological Load ◽  
Significant Difference

The in vivo mouse tibial loading model is used to evaluate the effectiveness of mechanical loading treatment against skeletal diseases. Although studies have correlated bone adaptation with the induced mechanical stimulus, predictions of bone remodeling remained poor, and the interaction between external and physiological loading in engendering bone changes have not been determined. The aim of this study was to determine the effect of passive mechanical loading on the strain distribution in the mouse tibia and its predictions of bone adaptation. Longitudinal micro-computed tomography (micro-CT) imaging was performed over 2 weeks of cyclic loading from weeks 18 to 22 of age, to quantify the shape change, remodeling, and changes in densitometric properties. Micro-CT based finite element analysis coupled with an optimization algorithm for bone remodeling was used to predict bone adaptation under physiological loads, nominal 12N axial load and combined nominal 12N axial load superimposed to the physiological load. The results showed that despite large differences in the strain energy density magnitudes and distributions across the tibial length, the overall accuracy of the model and the spatial match were similar for all evaluated loading conditions. Predictions of densitometric properties were most similar to the experimental data for combined loading, followed closely by physiological loading conditions, despite no significant difference between these two predicted groups. However, all predicted densitometric properties were significantly different for the 12N and the combined loading conditions. The results suggest that computational modeling of bone’s adaptive response to passive mechanical loading should include the contribution of daily physiological load.

scholarly journals Pore Geometry Optimization of Titanium (Ti6Al4V) Alloy, for Its Application in the Fabrication of Customized Hip Implants

2014 ◽  
Vol 2014 ◽  
pp. 1-12 ◽  
Author(s):  
Sandipan Roy ◽  
Debojyoti Panda ◽  
Niloy Khutia ◽  
Amit Roy Chowdhury
Keyword(s):  
Mechanical Response ◽  
Geometry Optimization ◽  
Combined Loading ◽  
Hip Implants ◽  
Loading Conditions ◽  
Mechanical Responses ◽  
Porous Ti ◽  
Physiological Loading ◽  
Solid Implants

The present study investigates the mechanical response of representative volume elements of porous Ti-6Al-4V alloy, to arrive at a desired range of pore geometries that would optimize the reduction in stiffness necessary for biocompatibility with the stress concentration arising around the pore periphery, under physiological loading conditions with respect to orthopedic hip implants. A comparative study of the two is performed with the aid of a newly defined optimizing parameter called pore efficiency that takes into consideration both the stiffness quantity and the stress localization around pores. To perform a detailed analysis of the response of the porous structure over the entire spectrum of loading conditions that a hip implant is subjected toin vivo, the mechanical responses of 3D finite element models of cubic and rectangular parallelepiped geometries, with porosities varying over a range of 10% to 60%, are simulated under representative compressive, flexural as well as combined loading conditions. The results that are obtained are used to suggest a range of pore diameters that lower the effective stiffness and modulus of the implant to around 60% of the stiffness and modulus of dense solid implants while keeping the stress levels within permissible limits.

scholarly journals A novel algorithm to predict bone changes in the mouse tibia properties under physiological conditions

2019 ◽  
Vol 19 (3) ◽  
pp. 985-1001 ◽  
Author(s):  
Vee San Cheong ◽  
Ana Campos Marin ◽  
Damien Lacroix ◽  
Enrico Dall’Ara
Keyword(s):  
Musculoskeletal Diseases ◽  
Mechanistic Model ◽  
Bone Adaptation ◽  
Mechanical Stimuli ◽  
Bone Apposition ◽  
Physiological Loading ◽  
Significant Difference ◽  
Subject Specific ◽  
Bone Changes ◽  
Mouse Tibia

AbstractUnderstanding how bone adapts to mechanical stimuli is fundamental for optimising treatments against musculoskeletal diseases in preclinical studies, but the contribution of physiological loading to bone adaptation in mouse tibia has not been quantified so far. In this study, a novel mechanistic model to predict bone adaptation based on physiological loading was developed and its outputs were compared with longitudinal scans of the mouse tibia. Bone remodelling was driven by the mechanical stimuli estimated from micro-FEA models constructed from micro-CT scans of C57BL/6 female mice (N = 5) from weeks 14 and 20 of age, to predict bone changes in week 16 or 22. Parametric analysis was conducted to evaluate the sensitivity of the models to subject-specific or averaged parameters, parameters from week 14 or week 20, and to strain energy density (SED) or maximum principal strain (εmaxprinc). The results at week 20 showed no significant difference in bone densitometric properties between experimental and predicted images across the tibia for both stimuli, and 59% and 47% of the predicted voxels matched with the experimental sites in apposition and resorption, respectively. The model was able to reproduce regions of bone apposition in both periosteal and endosteal surfaces (70% and 40% for SED and εmaxprinc, respectively), but it under-predicted the experimental sites of resorption by over 85%. This study shows for the first time the potential of a subject-specific mechanoregulation algorithm to predict bone changes in a mouse model under physiological loading. Nevertheless, the weak predictions of resorption suggest that a combined stimulus or biological stimuli should be accounted for in the model.

Design of Pipeline Composite Repairs: From Lab Scale Tests to FEA and Full Scale Testing

2014 ◽  
Author(s):  
Remy Her ◽  
Jacques Renard ◽  
Vincent Gaffard ◽  
Yves Favry ◽  
Paul Wiet
Keyword(s):  
Finite Element ◽  
Full Scale ◽  
Combined Loading ◽  
Material Strength ◽  
Repair System ◽  
Loading Conditions ◽  
Original Design ◽  
Composite Repair ◽  
Repair Systems ◽  
Composite Properties

Composite repair systems are used for many years to restore locally the pipe strength where it has been affected by damage such as wall thickness reduction due to corrosion, dent, lamination or cracks. Composite repair systems are commonly qualified, designed and installed according to ASME PCC2 code or ISO 24817 standard requirements. In both of these codes, the Maximum Allowable Working Pressure (MAWP) of the damaged section must be determined to design the composite repair. To do so, codes such as ASME B31G for example for corrosion, are used. The composite repair systems is designed to “bridge the gap” between the MAWP of the damaged pipe and the original design pressure. The main weakness of available approaches is their applicability to combined loading conditions and various types of defects. The objective of this work is to set-up a “universal” methodology to design the composite repair by finite element calculations with directly taking into consideration the loading conditions and the influence of the defect on pipe strength (whatever its geometry and type). First a program of mechanical tests is defined to allow determining all the composite properties necessary to run the finite elements calculations. It consists in compression and tensile tests in various directions to account for the composite anisotropy and of Arcan tests to determine steel to composite interface behaviors in tension and shear. In parallel, a full scale burst test is performed on a repaired pipe section where a local wall thinning is previously machined. For this test, the composite repair was designed according to ISO 24817. Then, a finite element model integrating damaged pipe and composite repair system is built. It allowed simulating the test, comparing the results with experiments and validating damage models implemented to capture the various possible types of failures. In addition, sensitivity analysis considering composite properties variations evidenced by experiments are run. The composite behavior considered in this study is not time dependent. No degradation of the composite material strength due to ageing is taking into account. The roadmap for the next steps of this work is to clearly identify the ageing mechanisms, to perform tests in relevant conditions and to introduce ageing effects in the design process (and in particular in the composite constitutive laws).

In vitro biomechanical comparison of load to failure testing of a canine unconstrained medial compartment elbow arthroplasty system and normal canine thoracic limbs

2013 ◽  
Vol 26 (05) ◽  
pp. 356-365 ◽  
Author(s):  
K. L. Wendelburg ◽  
S. Tepic ◽  
S. M. Stover ◽  
T. Garcia-Nolen ◽  
P. B. Stearns ◽  
...  
Keyword(s):  
Axial Load ◽  
Failure Modes ◽  
Ex Vivo ◽  
Medial Compartment ◽  
Elbow Arthroplasty ◽  
Total Arthroplasty ◽  
Significant Difference ◽  
Load To Failure ◽  
And Control

SummaryElbow dysplasia, primarily affecting the medial compartment, is the most common cause of lameness in the thoracic limb. Elbow arthroplasty is an option for end stage or severely affected patients. The purpose of this study was to compare ex vivo axial load to failure of an implanted novel elbow arthroplasty system to control limbs. The partial arthroplasty is a medial compartmental, unconstrained system, intended to allow conversion to total arthroplasty. We hypothesized that there would not be any significant difference between implanted and controlled limbs when loaded to failure. Six pairs of medium mixed breed canine cadaveric thoracic limbs were prepared for comparison of failure loading of control and implanted limbs. Axial compression was performed using a mechanical testing system. Failure loads were normalized to bodyweight. The mean normalized failure load (N/kg) for the implanted limbs and control limbs were 2.47 (range: 1.62-3.38) and 2.68 (range: 2.25-3.25), respectively. An implanted to control ratio of 0.93 ± 0.19 was calculated. The difference between paired control and implanted limbs in normalized failure loading was not significant (p = 0.38). There were not any differences noted in the yield load (p = 0.30), stiffness (p = 0.62), or energy (0.58). Failure modes were recorded. We concluded that the differences between implanted and control limbs in supra-physiologic axial load to failure were not significant.

In Vitro Experimental Testing of a Cervical Implanted Unit

2008 ◽  
Vol 399 ◽  
pp. 205-210
Author(s):  
Dan Ioan Stoia ◽  
Nicolae Faur ◽  
Mirela Toth-Taşcău ◽  
Laurenţiu Culea
Keyword(s):  
Experimental Testing ◽  
Metal Structure ◽  
Anatomical Structure ◽  
Loading Conditions ◽  
Physiological Conditions ◽  
Biomechanical Behavior ◽  
Physiological Loading ◽  
Extreme Load ◽  
Symmetrical Loading

The paper describes the biomechanical behavior of a cervical implanted unit (CIU) in two conditions: during the physiological and extreme loading. In order to reveal these behaviors, the anatomical structure composed by the C2 and C3 cervical vertebras was implanted using a plate-screws metal structure. The implant was design to perform dynamical, by allowing longitudinal, transversal and rotational movements. The physiological conditions were simulated by the pulsatory negative loading, while the extreme loading was simulated by the alternant symmetrical loading. The tests reveal two behaviors: the durability of the CIU in the physiological loading conditions and the failure of the structure under extreme load.

scholarly journals Three-Dimensional Buckling Analysis of Functionally Graded Saturated Porous Rectangular Plates under Combined Loading Conditions

2021 ◽  
Vol 11 (21) ◽  
pp. 10434
Author(s):  
Faraz Kiarasi ◽  
Masoud Babaei ◽  
Kamran Asemi ◽  
Rossana Dimitri ◽  
Francesco Tornabene
Keyword(s):  
Three Dimensional ◽  
Functionally Graded ◽  
Constitutive Law ◽  
Combined Loading ◽  
Rectangular Plates ◽  
Loading Conditions ◽  
Classical Elasticity ◽  
Novel Approach ◽  
Buckling Behavior ◽  
Generalized Differential

The present work studies the buckling behavior of functionally graded (FG) porous rectangular plates subjected to different loading conditions. Three different porosity distributions are assumed throughout the thickness, namely, a nonlinear symmetric, a nonlinear asymmetric and a uniform distribution. A novel approach is proposed here based on a combination of the generalized differential quadrature (GDQ) method and finite elements (FEs), labeled here as the FE-GDQ method, while assuming a Biot’s constitutive law in lieu of the classical elasticity relations. A parametric study is performed systematically to study the sensitivity of the buckling response of porous structures, to different input parameters, such as the aspect ratio, porosity and Skempton coefficients, along with different boundary conditions (BCs) and porosity distributions, with promising and useful conclusions for design purposes of many engineering structural porous members.

scholarly journals The potentiation of Mangifera casturi bark extract on interleukin- 1β and bone morphogenic protein-2 expressions during bone remodeling after tooth extraction

2017 ◽  
Vol 50 (1) ◽  
pp. 36
Author(s):  
Bayu Indra Sukmana ◽  
Theresia Indah Budhy ◽  
I Gusti Aju Wahju Ardani
Keyword(s):  
Bone Remodeling ◽  
Tooth Extraction ◽  
Alveolar Bone ◽  
Interleukin 1 ◽  
Bone Morphogenic Protein ◽  
Bark Extract ◽  
Control Group ◽  
Tooth Decay ◽  
Significant Difference ◽  
Bone Morphogenic Protein 2

Background: The main oral health problem in Indonesia is the high number of tooth decay. Tooth extraction is the treatment often received by patients who experience tooth decay and the wound caused by alveolar bone resorption. Bark of Mangifera casturi has been studied and proven to contain secondary metabolite which has the ability to increase osteoblast’s activity and suppress osteoclast’s activity. Purpose: The purpose of this study was to analyze interleukin-1 beta (IL-1β) and bone morphogenic protein-2 (BMP-2) activities during bone remodeling after Mangifera casturi’s bark extract treatment. Method: This study was laboratory experimental research with randomized post-test only control group design. The Mangifera casturi bark was extracted using 96% ethanol maceration and n-hexane fractionation. This study used 40 male Wistar rats which are divided into 4 groups and the tooth extraction was performed on the rats’ right mandible incisive tooth. The four groups consisted of 6.35%, 12.7%, 25.4% extract treatment group, and a control group. Wistar’s mandibles were decapitated on the 7th and 14th day after extraction. Antibody staining on preparations for the examination of IL-1β and BMP-2 expressions was done using immunohistochemistry. Result: There was a significant difference of IL-1β and BMP-2 expressions in 6,35%, 12,7%, and 25,4% treatment groups compared to control group with p<0.05. Conclusion: Mangifera casturi’s bark extract was able to suppress the IL-1β expression and increase the BMP-2 expression during bone remodeling after tooth extraction.

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