Biomechanics of Bone / Bone Biomechanics
Fereshteh Alizadeh Fard; Majid Mirzaei
Volume 14, Issue 2 , July 2020, , Pages 121-131
Abstract
Regarding the application of testing and analysis of bone fractures in both medical and engineering fields, finding proper specimens for measuring fracture properties is important. In this study, the experimental and numerical fracture analyses of bovine cortical bone were performed for 4 anatomical ...
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Regarding the application of testing and analysis of bone fractures in both medical and engineering fields, finding proper specimens for measuring fracture properties is important. In this study, the experimental and numerical fracture analyses of bovine cortical bone were performed for 4 anatomical regions using arc-shaped specimens. The tensile fracture tests for arc-shaped specimens were performed at ambient temperature. In practice, the stress intensity factor was calculated using standard analytical formula for arc-shaped specimens and also the related finite element (FE) models. In order to validate the FE models, the stress and strain analyses results were compared with the results obtained from digital image correlation (DIC) method. The very good agreement between these results was indicative of the accuracy of FE analyses. There were also good correlations between the initiation and propagation of crack from both experimental and FE results and the measured fracture toughness values were in good agreement with those reported in the literature. The results of this study showed that the analytical stress intensity expressions can give accurate results for the arc-shaped specimens excised from posterior and anterior regions. However, for the medial and lateral regions only the FE models can provide the required accuracy.
Biomechanics of Bone / Bone Biomechanics
Iman Zoljanahi Oskui
Volume 12, Issue 1 , June 2018, , Pages 75-84
Abstract
With the increase in lifespan there are many concerns related to ability of the hard tissues such as teeth to meet the physical demands over an extended period of function. The dentin has a special microstructural feature that governs its mechanical behavior, e.g., fracture mechanics: cylindrical tubules ...
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With the increase in lifespan there are many concerns related to ability of the hard tissues such as teeth to meet the physical demands over an extended period of function. The dentin has a special microstructural feature that governs its mechanical behavior, e.g., fracture mechanics: cylindrical tubules that are called dentin tubules. These tubules are gradually occluded in the elderly. The present study is aimed to investigate the effects of microstructure and its aging-related changes of the considered fiber-reinforced composite dentin on the fracture behavior and crack propagation trajectory, utilizing linear elastic fracture mechanics and finite element method. Obtained results indicate that the crack propagation path depends on geometrical microstructure of the dentin as well as respective mechanical properties and arrangement of dentin tubules. Also our results delineate that occlusion of dentinal tubule due to the aging plays a significant role at crack propagation trajectory and behaves as a barrier to crack growth.
Biomechanics of Bone / Bone Biomechanics
Mahmoud Reza Azghani; Sharareh Kian-Bostanabad; Tara Ahmadi; Hamid Khabiri
Volume 10, Issue 4 , January 2017, , Pages 339-346
Abstract
Long bone fracture is the most prevalent traumatic fractures that accures due to the strike and attacted load exertions, which one of them is the butterfly fracture. This type of fracture may happen with sudden and combined forces. Since in this type of fracture, the number of fracture lines is more ...
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Long bone fracture is the most prevalent traumatic fractures that accures due to the strike and attacted load exertions, which one of them is the butterfly fracture. This type of fracture may happen with sudden and combined forces. Since in this type of fracture, the number of fracture lines is more than other types of fractures, developing a prohibitive method may be usfull. The present paper is aimed to investigate the effects of strain rate and use of fastener on butterfly fracture in bone samples. To this end, invivo sheep metacarpal bone samples were examined in four groups: distinguished based on different strain rates, loading conditions and boundry conditions. The first one underwent pure bending at rate of 20 mm/s. The second group and third group experience combined bending and axial compression at rate of 5 mm/s and 20 mm/s, respectively. Bone samples in the fourth group, however, sustained combined loading of bending and axial compression while their ends had been fixed. Comparison between the first and third groups significantly stated that exerting axial compression increases the number of butterfly fractured samples. Results show that at the higher strain rates, the number of butterfly fracture increases. Constraining the ends of the bone samples, on the other hand, led to dissipate the effects of combined loading and also high strain rate. Furthermore, a considerable accordance was observed based on Pearson Correlation test by amount of 0.947.
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
Masume Khaghani; Zahra Golniya; Ali Doostmohammadi
Volume 6, Issue 1 , June 2012, , Pages 1-7
Abstract
The aim of this work was evaluating of zirconia nanoparticles’ effect on physical and mechanical properties of dental glass ionomer cements (GICs). Ceramic part of GIC was prepared using melting method and zirconia nanoparticles were added to GIC in 1, 3 and 5 weight percent. Characterization tests ...
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The aim of this work was evaluating of zirconia nanoparticles’ effect on physical and mechanical properties of dental glass ionomer cements (GICs). Ceramic part of GIC was prepared using melting method and zirconia nanoparticles were added to GIC in 1, 3 and 5 weight percent. Characterization tests and compressive strength evaluation of nanocomposite samples were carried out. The XRD results showed that the prepared ceramic part of GIC was completely amorphous and can be used as the matrix of composite. The result of XRF showed that the chemical composition of ceramic part of GIC was similar to expected composition. Also the results of mechanical properties determination analysis showed that the addition of zirconia nanoparticles to GIC could improve the compressive strength. The maximum of this strength obtained using 1% wt of GIC in zirconia composite. Increasing the nanoparticles content resulted in decrease of compressive strength but the strength of composite with any composition was more than the strength of control sample. According to the results of this study, the most proper composite was the one containing1%wt zirconia nanoparticles.
Biomechanics of Bone / Bone Biomechanics
Hoda Salemi; Ali Asghar Behnamghader; Mohammad Reza Baghaban Eslaminejad; Mohammad Ataei
Volume 6, Issue 4 , June 2012, , Pages 249-255
Abstract
Collagen and Hydroxyapatite (HA) nanoparticles are significant constituent of the natural bone. In this study, the effect of collagen on the morphological and phase characteristics of calcium phosphate nanoparticles was investigated. The synthesis reaction was initiated by mixing H3PO4 as phosphorous ...
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Collagen and Hydroxyapatite (HA) nanoparticles are significant constituent of the natural bone. In this study, the effect of collagen on the morphological and phase characteristics of calcium phosphate nanoparticles was investigated. The synthesis reaction was initiated by mixing H3PO4 as phosphorous source and CaCl2 as calcium source in presence of Collagen Type 1. Collagen concentration in suspension and Ca to P ratio was 1% and 1.67 respectively. The morphology and structure of samples (with collagen and without collagen), heat treated at 600 0C were characterized by X-Ray diffraction (XRD), Fourier transformation infrared (FTIR) and Scanning electron microscopy (SEM). More fine and flake-like shape particles were observed in the SEM images of sample synthesized in the presence of collagen compared to the control sample which was constituted of larger granular particles. The XRD results revealed the powders were composed of hydroxyapatite and octacalcium phosphate and the sample synthesized in the presence of collagen was less crystalline. The amide bands of collagen and P-O and OH characteristic peaks were identified in FT-IR spectra.
Biomechanics of Bone / Bone Biomechanics
Mina Gharenazifam; Ehsan Arbabi
Volume 6, Issue 4 , June 2012, , Pages 267-278
Abstract
One of the main causes of early osteoarthritis of the hip is Femoroacetabular Impingement (FAI). When the femoral head loses its spherical shape at head-neck junction, a special type of impingement, called Cam impingement, occurs. Alpha angle can be used as a geometric parameter for evaluating this kind ...
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One of the main causes of early osteoarthritis of the hip is Femoroacetabular Impingement (FAI). When the femoral head loses its spherical shape at head-neck junction, a special type of impingement, called Cam impingement, occurs. Alpha angle can be used as a geometric parameter for evaluating this kind of anatomic deformity. In this article we propose a fully automatic strategy for estimating alpha angle by analyzing 3D data. In the proposed strategy a radial plane around the femoral head-neck axis is rotated in order to provide alpha angles in different orientations. For evaluating the proposed method, the alpha angle of twelve 3D femur models of female subjects, reconstructed from magnetic resonance images (including both right and left femur), have been estimated. The mean and standard deviation of these estimated alpha angles have been found to be in good agreement with the expected values for alpha angle in healthy human. In addition, the effect of the data resolution on the provided results has been evaluated in terms of accuracy and speed, by using four different resolutions of 3D meshes. The results indicate that using 64 times lower data resolution can increase the computational speed up to about 8 times and add an average error of about 2° to the estimated alpha angles.
Biomechanics of Bone / Bone Biomechanics
Sara Sadat Farshidfar; Mohammad Reza Mallakzadeh; Hamid Reza Yazdi
Volume 6, Issue 1 , June 2012, , Pages 49-55
Abstract
The aim of this study was to compare the contact area and pressure within medial and lateral compartments of tibiofemoral joint during internal and external rotational deformities of tibia bone. Methods: five lower extremities of fresh frozen human cadavers were tested by using a mechanical system was ...
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The aim of this study was to compare the contact area and pressure within medial and lateral compartments of tibiofemoral joint during internal and external rotational deformities of tibia bone. Methods: five lower extremities of fresh frozen human cadavers were tested by using a mechanical system was designed for the first time in IRAN to simulate the static position loading of standing on two legs in full extension knee under 400N loading along the longitudinal axis of each foot. The contact area and pressure were measured by FUJIfilm Prescale films under axial loading in neutral rotation and serial mal-rotations of tibia from 40 degrees external to 40 degrees internal mal-rotations in 10 degrees increments by tibial osteotomy. Results: contact area and lateral compartment contact pressure was not significantly affected by mal-rotations. Medial compartment contact pressure increased with external and decreased with internal mal-rotations. Changing the medial compartment contact pressure of tibiofemoral joint in various rotational alignments of tibia can be very effective in rapid growth of knee osteoarthritis symptoms specially in people with unilateral medial knee osteoarthritis.
Biomechanics of Bone / Bone Biomechanics
Mohammad Mehdi Khani; Mohammad Tafazzoli Shadpour; Farzane Aghajani; Peyman Naderi
Volume 5, Issue 1 , June 2011, , Pages 13-20
Abstract
Stress analysis is a proper tool in evaluation of vulnerable regions of dental tissues exposed to cyclic loading due to mastication and other physiological functions. In this study, effects of visco-elastic property of dental components on the distribution of stress are investigated in finite element ...
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Stress analysis is a proper tool in evaluation of vulnerable regions of dental tissues exposed to cyclic loading due to mastication and other physiological functions. In this study, effects of visco-elastic property of dental components on the distribution of stress are investigated in finite element models of upper central tooth prone to dynamic loading. Sensitivity of stress pulse to the visco-elastic property is studied. Results indicate reduction of stress pulse amplitude by elevation of visco-elastic parameter with highest effect in enamel-cementum junction and then in enamel-dentin junction. The visco-elastic property causes smoothening of the stress distribution in dental tissues. Such effect is due to reduction of stress wave amplitude and elevation of the ratio of minimum to maximum stress values. Increased visco-elasticity of components results in elevated phase shift between load and stress waves and higher attenuation of stress wave. This causes slow propagation of attenuated wave leading to lower maximum stress after reflection of stress wave in boundaries and junctions.
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.
Biomechanics of Bone / Bone Biomechanics
Behnoud Haghighi; Masoud Tahani; Gholam Reza Rouhi
Volume 5, Issue 1 , June 2011, , Pages 33-44
Abstract
Orthopedic screws are widely used devices for fixation of bone fractures. Progressive loosening of bone fixation screws, induced by stress shielding and subsequent adaptive bone remodeling, results in bone loss around the screw. A set of two-dimensional finite element models including cortical and cancellous ...
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Orthopedic screws are widely used devices for fixation of bone fractures. Progressive loosening of bone fixation screws, induced by stress shielding and subsequent adaptive bone remodeling, results in bone loss around the screw. A set of two-dimensional finite element models including cortical and cancellous bone with a functionally graded Ti-Hap screw was developed. A dimensionless set of stress-transfer parameters (STP) and strain energy density-transfer parameter (SEDTP) were developed to quantify the screw–bone load sharing. Lower STP and SEDTP values indicate weak stress and strain energy density transfer to bone which is a sign of stress shielding. The results indicated that STP and SEDTP values for FGM screw are higher than those of a fully metal screw. Moreover, reducing elastic modulus of metal fraction and increasing the volume fraction of ceramic decrease the stress shielding. For a partially graded screw (with both homogenous and FGM parts), the longer FGM part is, the greater are STP and SEDTP values. Furthermore, the results showed that decreasing compositional distribution exponent which shows composition change of FGM content from metal fraction toward ceramic fraction, increases the parameters. Results from this study are in admissible agreement with available clinical and experimental study.
Biomechanics of Bone / Bone Biomechanics
Mahmoud Azami; Fathollah Moztarzadeh; Mohammad Rabiee
Volume 3, Issue 4 , June 2009, , Pages 275-284
Abstract
During past decade, using biomimetic approaches has received much attention by scientists in the field of tissue substitutes preparation. These approaches have been employed for synthesis of bone tissue engineering scaffolds in the case of either materials or synthesis methods. In this study, an apatite ...
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During past decade, using biomimetic approaches has received much attention by scientists in the field of tissue substitutes preparation. These approaches have been employed for synthesis of bone tissue engineering scaffolds in the case of either materials or synthesis methods. In this study, an apatite phase has been synthesized within gelatin hydrogel in biomimetic condition. The obtained composite hydrogel has changed to a porous scaffold with the application of freeze drying technique in order to be used in bone tissue engineering. To characterize the chemical composition and crystal structure of the synthesized precipitate within hydrogel, FTIR, XRD and TEM analysis were used. Surface morphology and porous structure of the scaffold were studied with SEM. SEM analysis was also used to investigate the quality of cultured osteoblast cells activity. Results approved formation of an apatite phase within gelatin hydrogel in biomimetic condition with crystallite size ranging between 7-10 nm. Porosity percentage of the obtained nanocomposite scaffold was about 82% with pores sizes in the range of 100-350μm. Young’s elastic modulus of the scaffold was comparable with that of the spongy bone. The osteoblast cells cultured on the scaffold showed adhesion, immigration and extracellular matrix excretion on the scaffold internal surfaces. Thus, obtained results indicated the potential ability of the prepared biomimetic bone tissue engineering scaffold to be used in bone tissue repair process.
Biomechanics of Bone / Bone Biomechanics
Masoume Haghbin Nazarpak; Farzane Pourasgari; Mohammad Nabi Sarbolouki
Volume 3, Issue 4 , June 2009, , Pages 291-298
Abstract
The scaffolds for bone tissue engineering should consider the functional requirements: porosity, biocompatibility, and biodegradability. In this study, porous Poly (lactic-co-glycolic acid)/Hydroxyapatite composites were prepared with different weight ratios. Porous samples were fabricated by freeze-extraction ...
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The scaffolds for bone tissue engineering should consider the functional requirements: porosity, biocompatibility, and biodegradability. In this study, porous Poly (lactic-co-glycolic acid)/Hydroxyapatite composites were prepared with different weight ratios. Porous samples were fabricated by freeze-extraction method, coated with triblock copolymer and sterilized by UV. Then, human mesenchymal stem cells were cultured on scaffolds. Microstructural studies with SEM suggest the formation of about 50 micrometer size porous structure and interconnected porosity so that cells adhesion within the structure is well in depth in coated samples. DAPI fluorescence microscopy showed cells adhesion to the coated scaffolds and cells diffusion into the pores. Also, direct assay of cell proliferation performed with MTT test showed that, cells grew on the scaffold similar to or more than control samples result. Therefore, these findings suggest that the triblock-coated Poly (lactic-coglycolic acid)/ Hydroxyapatite porous composite scaffolds could provide cells adhesion and proliferation and are appropriate matrices for bone tissue engineering.
Biomechanics of Bone / Bone Biomechanics
Shahab Mansourbaghaei; Majid Haghayegh; Seyed Mohammad Rajaei
Volume 3, Issue 3 , June 2009, , Pages 243-253
Abstract
An analytical method to predict the response of the inclined impact of a fluid filled elastic spherical shell having an arbitrary thickness with an elastic toroid is investigated in this paper which can be a model for analytical evaluation of blunt impact on the human head. The study is performed under ...
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An analytical method to predict the response of the inclined impact of a fluid filled elastic spherical shell having an arbitrary thickness with an elastic toroid is investigated in this paper which can be a model for analytical evaluation of blunt impact on the human head. The study is performed under a combination of Hertzian contact theory and the local effect of membrane and bending of the shell in order to state the implicit equation to determine the transmitted force. With respect to the analytical responses, it is concluded that transmitted force decreases and contact duration increases by increasing of attack angle in constant initial velocity. In addition, closed form solution is presented to obtain impact parameters including the duration, the maximum transferred load and the maximum acceleration of the shell which particularly important for the researchers. Therefore investigation of the important quantities of the impact problem with closed form solution is possible. On the other hand, limiting cases will be discussed in next step and the concluded results are validated by finite element methods to verify the response of the model. In this step, a good agreement between analytical responses and numerical results is observed that reveals the correctness of analytical equations. In the final step of this research, obtained results are compared with experimental data.
Biomechanics of Bone / Bone Biomechanics
Seyed Mahmoud Rabiei; Fathollah Moztarzadeh; Mehran Solati Hashjin; Saeed Hesaraki
Volume 1, Issue 2 , June 2007, , Pages 105-110
Abstract
In this research, the influence of NaH2PO4.2H2O with different concentrations on setting time and compressive strength of bone cement based on hydroxyapatite was investigated. Hydroxyapatite cement is of calcium phosphate bone cements, which can be considered as the best substitute for hard tissues. ...
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In this research, the influence of NaH2PO4.2H2O with different concentrations on setting time and compressive strength of bone cement based on hydroxyapatite was investigated. Hydroxyapatite cement is of calcium phosphate bone cements, which can be considered as the best substitute for hard tissues. The powder phase of the cement was prepared from various compositions of calcium phosphates such: tricalcium phosphate (TCP), calcium carbonate (CaCO3) and montite (CaHPO4) as constant and the liquid part using NaH2PO4.2H2O solution with different concentrations. The influences of liquid/powder ratio L/P (ml/g) was investigated on the initial and final setting times and compressive strengths of the cement. According to the obtained results, with optimum concentrations of the liquid phase, this cement seems suitable for clinical applications.
Biomechanics of Bone / Bone Biomechanics
Ahmad Raeisi Najafi; Ahmad Reza Arshi; Mohammad Reza Eslami; Shahriar Fariborz; Mansour Moeinzadeh
Volume 1, Issue 3 , June 2007, , Pages 177-188
Abstract
A two dimensional finite element model for the human Haversian cortical bone is represented. The interstitial bone tissue, the osteons and the cement line were modeled as the matrix, the fibers and the interface, respectively. This was due to similarities between fiber-ceramic composite materials and ...
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A two dimensional finite element model for the human Haversian cortical bone is represented. The interstitial bone tissue, the osteons and the cement line were modeled as the matrix, the fibers and the interface, respectively. This was due to similarities between fiber-ceramic composite materials and the human Haversian cortical bone. The stress intensity factor in the microcrack tips vicinity was computed using the linear elastic fracture mechanics theory and assuming a plane strain condition. It was therefore possible to study the effect of microstructure and mechanical properties of Haversian cortical bone on microcrack propagation trajectory. The results indicated that this effect was limited to the vicinity of the osteon. If both osteon and cement line were assumed to be softer than the interstitial tissue, the stress intensity factor was increased when the crack distance to the osteon reduced. The stress intensity factor decreased if both osteon and cement line were assumed to be stiffer than the interstitial tissue. The resulting simulation indicated that the effect of existence of osteon on the stress intensity factor was no significance, if both the interstitial tissue and cement line were assumed either stiffer or softer than the osteon. Microcrack trajectory was observed to deviate from the osteon under tensile loading; indicating an independence from the mechanical properties of various tissues. In fact, the microcrack adopts a trajectory between the osteons, thereby increasing the necessary absorbed energy for fracture. This results in an increase in the human Haversian cortical bone toughness. The result of this finite element modeling has been confirmed by through evaluation and comparison made with experimental results.
Biomechanics of Bone / Bone Biomechanics
Mohammad Haghpanahi; Mehdi Pourdanial
Volume 1, Issue 4 , June 2007, , Pages 289-299
Abstract
A 3D anatomically accurate finite element model of the human first cervical vertebra (atlas), including cortical and cancellous bones, was developed in ANSYS 9 based on CT-scan images. The main objective was to investigate the effect of cancellous bone on the value and distribution of maximum and average ...
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A 3D anatomically accurate finite element model of the human first cervical vertebra (atlas), including cortical and cancellous bones, was developed in ANSYS 9 based on CT-scan images. The main objective was to investigate the effect of cancellous bone on the value and distribution of maximum and average Von Mises stress in Atlas. The results showed that the material property of cancellous bone has no significant effect on the location of maximum stress and the pattern of average stress distribution in anterior arch, the junction of posterior arch and lateral mass and the groove of the posterior arch. Although the presence of cancellous bone in the model yielded higher values for the maximum and average stresses. The boundary condition had a considerable effect on this increase. Altering the material property of cancellous bone under neutral and hyperextension loading configurations, affected the average stress only in cancellous bone in the lateral mass, but change in the material property of cortical bone resulted in average stress change both in the cortical and cancellous bones, and in the lateral displacement of the lateral mass as well. The interconnected effects of changing the material properties of these two bone tissues were also studied.
Biomechanics of Bone / Bone Biomechanics
Abdorreza Sheikh Mehdi Mesgar; Zahra Mohammadi; Fathollah Moztarzadeh; Mahtab Ashrafi Khouzani; Zeinab Sadat Mohammadi
Volume 1, Issue 1 , June 2007, , Pages 39-51
Abstract
Amorphous carbonated calcium phosphates (ACCPs) with different carbonate contents and Ca/P ratios were reproducible synthesized by the reaction parameters as low temperature, high pH value, using initial solutions of calcium and phosphate at low concentrations, and various amounts of carbonate, as well ...
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Amorphous carbonated calcium phosphates (ACCPs) with different carbonate contents and Ca/P ratios were reproducible synthesized by the reaction parameters as low temperature, high pH value, using initial solutions of calcium and phosphate at low concentrations, and various amounts of carbonate, as well as freeze drying of the precipitates. The addition of carbonate to the solutions led to form precipitates with higher Ca/P ratios with respect to the initial solutions. Heat treatment of freezedried ACCPs at 500 °C had no influence on their amorphous structure. The results of elemental carbon and thermal analysis showed that the carbonate may be eliminated in a wide range of temperature (500−1150oC). Dissolution rate of ACCPs in the simulated bone resorption medium was dependent to the contents of carbonate and remaining water. Dissolution rate of the specimens with higher carbonate contents was controlled by the carbonate content, but the amount of remaining water had major influence on the dissolution rate of the precipitates with lower carbonate contents. The dissolution kinetics was found to follow a shrinking-core model, with product layer as the ratedetermining step. Formation of an amorphous calcium phosphate and/or thermodynamically desirable dicalcium phosphate dihydrate as possible product layer prevents complete resorption of ACCPs under bone resorption conditions, and promotes osteoblastic activation process through nucleation and growth of biological apatite.
Biomechanics of Bone / Bone Biomechanics
Mohammad Haghpanahi; Ali Gorginzadeh; Saba Sohrabi
Volume 1, Issue 2 , June 2007, , Pages 131-136
Abstract
Considering the life threatening consequences of the cervical spine injuries, the study of its biomechanical behavior has become important. The most common axis (second cervical vertebra) injury is called odontoid fracture, the majority of which is type II or dens fracture. In this study, an exact 3D ...
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Considering the life threatening consequences of the cervical spine injuries, the study of its biomechanical behavior has become important. The most common axis (second cervical vertebra) injury is called odontoid fracture, the majority of which is type II or dens fracture. In this study, an exact 3D finite element model of axis was developed and analyzed. To evaluate the stress distributions in the odontoid process during type II injuries, pressure loads were applied on the dens at locations where it is likely to come into contact with the surrounding neck construct. Results indicate stress concentration in the odontoid junction with the vertebral body, which suggests that there is a possibility of occurring type II fracture in the case of impaction of odontoid with atlas anterior arch, lateral masses and transverse ligament.
Biomechanics of Bone / Bone Biomechanics
Khalil Farhangdoust; Ali Banihashem; Ali Ghaneei
Volume -2, Issue 1 , July 2005, , Pages 1-8
Abstract
Using ceramic coatings has increased in popularity due to their compatibility with bone, absence of the fibrous layer at the coating-implant interface, and the stronger coating-bone bonding. Among these coatings, hydroxyapatite (HA) and fluoroapatite (FA) are more popular. For the first time in this ...
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Using ceramic coatings has increased in popularity due to their compatibility with bone, absence of the fibrous layer at the coating-implant interface, and the stronger coating-bone bonding. Among these coatings, hydroxyapatite (HA) and fluoroapatite (FA) are more popular. For the first time in this paper, modeling and stress analysis have been carried out for 24 implants in an axisymetric form using the finite element technique. Twelve of these samples belong to IMZ and the rest are from Dyna system. All implants had HA and FA coatings with thicknesses between 10 to 100 microns. The stress analysis results show that the stress concentration at the implant-coating and bone-coating bonding surfaces decreases with the increase of coating thickness. In addition, stress concentrations for implants with FA coatings are always more than those with HA coatings. In all implants, stress concentration has been observed around the bone crest.
Biomechanics of Bone / Bone Biomechanics
Seyed Hamed Hosseini Nasab; Farzam Farahmand; Mohammad Hossein Karegar Novin; Mohsen Karami
Volume -1, Issue 2 , June 2005, , Pages 159-172
Abstract
Several linear and nonlinear finite element models of intact and fixed lumbar spine were analyzed. The intact model was developed based on CT images, and following verification, was employed to simulate the spinal fixation procedure using two different commercial pedicle screw systems. The results including ...
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Several linear and nonlinear finite element models of intact and fixed lumbar spine were analyzed. The intact model was developed based on CT images, and following verification, was employed to simulate the spinal fixation procedure using two different commercial pedicle screw systems. The results including the force-deformation behavior and the stress distribution within the structures were studied in detail. The effects of pedicle morphology, insertion errors and material properties of bone graft on the stress distribution pattern within the vertebrae and implant components were also studied. The results suggest superiority of titanium implants over steel implants, necessity of bone graft insertion, and a higher failure risk for screws due to osteoporosis. It has been recommended that surgeons use thicker screws when dealing with pedicels with larger anterior posterior length and avoid insertion errors to minimize the risk of screw fracture.
