Finite element modelling of the Ilizarov external fixation system

Watson, M A; Mathias, K. J.; Maffulli, Nicola; Hukins, D. W. L.; Shepherd, Duncan E.T.

doi:10.1243/09544119jeim225

Cited by 20 publications

(21 citation statements)

References 11 publications

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“…Relating age and micro-architecture with apparent-level elastic constants: a micro-finite element study of female cortical bone from the anterior femoral midshaft 1 INTRODUCTION Numerous previous finite element (FE) studies have investigated the biomechanics of bone with orthopaedic implants; for example, fracture fixation [1][2][3], vertebral fixation [4], hip arthroplasty [5], and knee prostheses [6][7][8]. Depending on the outcome of interest, the results of such FE simulations may depend upon the specified elastic constants of bone tissues.…”

mentioning

confidence: 99%

Relating age and micro-architecture with apparent-level elastic constants: a micro-finite element study of female cortical bone from the anterior femoral midshaft

Donaldson

Pankaj

Cooper

et al. 2011

Proc Inst Mech Eng H

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Homogenized elastic properties are often assumed for macro-finite element (FE) models used in orthopaedic biomechanics. The accuracy of material property assignments may have a strong effect on the ability of these models to make accurate predictions. For cortical bone, most macro-scale FE models assume isotropic elastic material behaviour and do not include variation of material properties due to bone micro-architecture. The first aim of the present study was to evaluate the variation of apparent-level (homogenized) orthotropic elastic constants of cortical bone with age and indices of bone micro-architecture. Considerable age-dependent differences in porosity were noted across the cortical thickness in previous research. The second aim of the study was to quantify the resulting differences in elastic constants between the periosteum and endosteum. Specimens were taken from the anterior femoral midshaft of 27 female donors (age 53.4 +/- 23.6 years) and micro-FE (gFE) analysis was used to derive orthotropic elastic constants. The variation of orthotropic elastic constants (Young's moduli, shear moduli, and Poisson's ratios) with various cortical bone micro-architectural indices was investigated. The ratio of canal volume to tissue volume, Ca.V/TV, analogous to porosity, was found to be the strongest predictor (r2(ave) = 0.958) of the elastic constants. Age was less predictive (r2(ave) = 0.385) than Ca.V/TV. Elastic anisotropy increased with increasing Ca.V/TV, leading to lower elastic moduli in the transverse, typically less frequently loaded, directions. Increased Ca.V/TV led to a more substantial reduction in elastic constants at the endosteal aspect than at the periosteal aspect. The results are expected to be most applicable in similar midshaft locations of long bones; specific analysis of other sites would be necessary to evaluate elastic properties elsewhere. It was concluded that Ca.V/TV was the most predictive of cortical bone elastic constants and that considerable periosteal-endosteal variations in these constants can develop with bone loss.

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confidence: 99%

Relating age and micro-architecture with apparent-level elastic constants: a micro-finite element study of female cortical bone from the anterior femoral midshaft

Donaldson

Pankaj

Cooper

et al. 2011

Proc Inst Mech Eng H

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“…Since then, several other studies have been conducted (6)(7)(8)(9)(10)(11) . Studies using this technique have also been published in the Brazilian literature, but not with simulation of an external fixator (12)(13)(14) .…”

Section: Discussionmentioning

confidence: 99%

“…The commercial finite-element packages available are very versatile tools for evaluating the influence of A B C assembly parameters in relation to the axial stiffness of a particular external fixator, because of the ease of modifying the geometrical characteristics of the assembly and outline conditions of the model. The advantages of computational finite-element models are the possibilities of modifying various parameters easily and systematically (7) , evaluating the stiffness without the need for experimental tests (11) and dispensing with studies on animals, which are becoming increasingly difficult to undertake nowadays.…”

Section: Discussionmentioning

confidence: 99%

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Relação entre rigidez de fixador externo e quantidade de pinos: análise computacional por elementos finitos

Sternick¹,

Dallacosta²,

Bento³

et al. 2012

Rev. bras. ortop.

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Objective: To analyze the rigidity of a platform-type external fixator assembly, according to different numbers of pins on each clamp. Methods: Computer simulation on a large-sized Cromus dynamic external fixator (Baumer SA) was performed using a finite element method, in accordance with the standard ASTM F1541. The models were generated with approximately 450,000 quadratic tetrahedral elements. Assemblies with two, three and four Schanz pins of 5.5 mm in diameter in each clamp were compared. Every model was subjected to a maximum force of 200 N, divided into 10 sub-steps. For the components, the behavior of the material was assumed to be linear,

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“…Numerous experimental studies have investigated the influence of ICF frame elements and configurations on the biomechanical properties of the conventional ICF . However, there is only limited amount of data available on the biomechanical properties of TSF under different configurations .…”

Section: Introductionmentioning

confidence: 99%

Bone fracture healing under Ilizarov fixator: Influence of fixator configuration, fracture geometry, and loading

Ganadhiepan

Miramini

Patel

et al. 2019

Numer Methods Biomed Eng

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This study aims to enhance the understanding of the relationship between Ilizarov fixator configuration and its effects on bone fracture healing. Using Taylor spatial frame (TSF) as an example, the roles of critical parameters (ie, TSF ring diameter, wire pre-tension, fracture gap size, and axial load) that govern fracture healing during the early stages were investigated by using computational modelling in conjunction with mechanical testing involving an advanced 3D optical measurement system. The computational model was first validated using the mechanical test results and then used to simulate mesenchymal stem cell (MSC) differentiations within different regions of the fracture site under various combinations of TSF ring diameter, wire pre-tension, fracture gap size, and axial load values. Predicted spatially dependent MSC differentiation patterns and the influence of each parameter on differentiations were compared with in vivo results, and good agreement was seen between the two. Gap size was identified as the most influential parameter in MSC differentiation, and the influence of axial loading and TSF configuration (ie, ring diameter and wire pre-tension) on cell differentiation was seen to be gap size dependent. Most changes in cell differentiation were predicted in the external callus (periosteal), which is the crucial region of the callus in the early stages.However, for small gap sizes (eg, 1 mm), significant changes were predicted in the endosteal callus as well. The study exhibits the potential of computational models in assessing the performance of Ilizarov fixators as well as assisting surgeons in patient-specific clinical treatment planning. KEYWORDS 3D optical measurement system, mechanical test, mechano-regulation, mesenchymal stem cell, Taylor spatial frame

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Finite element modelling of the Ilizarov external fixation system

Cited by 20 publications

References 11 publications

Relating age and micro-architecture with apparent-level elastic constants: a micro-finite element study of female cortical bone from the anterior femoral midshaft

Relating age and micro-architecture with apparent-level elastic constants: a micro-finite element study of female cortical bone from the anterior femoral midshaft

Relação entre rigidez de fixador externo e quantidade de pinos: análise computacional por elementos finitos

Bone fracture healing under Ilizarov fixator: Influence of fixator configuration, fracture geometry, and loading

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