Spinal Biomechanics
Mohammad Nikkhoo; Sajjad Najafzadeh; Romina Kargar
Volume 9, Issue 4 , February 2015, , Pages 317-326
Abstract
Understanding the mechanism of artificial disc degeneration using animal models is useful to study the regenerative techniques in hope of finding potential therapeutic strategies. For any type of potential therapeutic techniques, first we need to have the degenerated model. Disc degeneration ...
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Understanding the mechanism of artificial disc degeneration using animal models is useful to study the regenerative techniques in hope of finding potential therapeutic strategies. For any type of potential therapeutic techniques, first we need to have the degenerated model. Disc degeneration can be mimicked in animal studies using needle puncture. However, the detailed mechanical response of the artificial degenerated disc using needle puncture under physiological diurnal activities has not been analyzed well.Hence, reverse finite element analyses combined with in-vitro experiments were used in this study to find the mechanical properties of intact (N=8) and injured discs using needle puncture (N=8). Afterward, specimen-specific FE models for 16 discs were simulated during physiological diurnal activity. The results showed that the variation of axial displacement, intradiscal pressure, and total fluid exchangein intact discs were significantly higher than the injured ones after 24h. But the maximum axial stress within disc was significantly higher in injured group. The achieved results are correlated with previous human cadaver data for natural disc degeneration. Therefore, it is concluded that the G-16needle puncture injury is a simple and cost-effective methodology which can be used to mimic the degeneration mechanism in animal models.
Biomechanics of Bone / Bone Biomechanics
Mohammad Nikkhoo; Ali Tahassori; Mohammad Haghpanahi
Volume 8, Issue 3 , September 2014, , Pages 203-212
Abstract
To develop the advanced technologies in medical device industry, design and manufacturing of cervical cage was performed in Iran for the first time. This research-based industrial project should be accomplished based on precise biomechanical studies and mechanical tests. Hence, this study presents the ...
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To develop the advanced technologies in medical device industry, design and manufacturing of cervical cage was performed in Iran for the first time. This research-based industrial project should be accomplished based on precise biomechanical studies and mechanical tests. Hence, this study presents the optimization and biomechanical functional investigations of the first Iranian cervical cage (Manufactured by Attila Ortopaed Co.). For this purpose the intact cervical spine (C2-C7) was developed and was validated with in-vitro experiments. Three inputs (i.e. geometrical parameters of the cage) and two outputs (i.e. deformation of the teeth in static and dynamic tests) parameters were selected for optimization procedure. Furthermore, the surgery in C5-C6 level was simulated by implanting the cervical cage. Finally, the biomechanical responses were investigated. The result confirmed that the biomechanical response of cervical cage is within the standard range and can be used well in clinics for surgical procedures.
Biomechanics of Bone / Bone Biomechanics
Mohammad Nikkhoo; Mohammad Haghpanahi; J. L. Wang; Mohammad Parnianpour
Volume 5, Issue 1 , June 2011, , Pages 21-32
Abstract
Prediction of the relationship between different types of mechanical loading and the failure of the intervertebral disc is so important to identify the risk factors which are difficult to study in vivo and in vitro. On the basis of finite element methods some of these issues may be overcome ...
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Prediction of the relationship between different types of mechanical loading and the failure of the intervertebral disc is so important to identify the risk factors which are difficult to study in vivo and in vitro. On the basis of finite element methods some of these issues may be overcome enabling more detailed assessment of the biomechanical behavior of the intervertebral disc. The objective of this paper is to develop a nonlinear axisymmetric poroelastic finite element model of lumbar motion segment and show its capability for studying the time-dependent response of disc. After comparison of the response of different models in quasi-static analysis, the poroelastic model of intervertebral disc is presented and the results of short-term, long-term creep tests and cyclic loading were investigated. The results of the poroelastic model are in agreement with experimental ones reported in the literature. Hence, this model can be used to study how different dynamic loading regimes are important as risk factors for initiation of intervertebral disc degeneration.
Tissue Engineering
Mohammad Haghpanahi; Mohammad Nikkhoo; Habibollah Peirovi
Volume 2, Issue 1 , June 2008, , Pages 47-56
Abstract
According to mechanobilogical studies as an infrastructure for tissue engineering researches, this paper presents a triphasic finite element modeling of intervertebral discs such a hydrated porous soft tissue. First, the governmental equations were derived on the basis of the laws of continuum mechanics. ...
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According to mechanobilogical studies as an infrastructure for tissue engineering researches, this paper presents a triphasic finite element modeling of intervertebral discs such a hydrated porous soft tissue. First, the governmental equations were derived on the basis of the laws of continuum mechanics. Then the standard Galerkin weighted residual method was used to form the finite element model. The implicit time integration schemes were applied to solve the nonlinear equations. The formulation accuracy and convergence for one dimensional case were examined with Simon's and Sun's analytical solutions and also Drost's experimental Data. It was shown that the mathematical model is in excellent agreement and has the capability to simulate the intervertebral disc response under different types of mechanical and electrochemical loading conditions. Finally, to have a short review of the capability of the model, a homogenous two dimensional version of the model was applied to simulate the response of a simple sagittal slice of the intervertebral disc.
