Biomechanics / Biomechanical Engineering
Alireza Rezaie Zangene; Ramila Abedi Azar; Hamidreza Naserpour; seyyed hamed hosseini nasab
Volume 16, Issue 4 , March 2023, , Pages 51-60
Abstract
Knee joint contact force (KCF) plays a significant role in the occurrence and progression of knee osteoarthritis (KOA) disease. KCF can be used in monitoring rehabilitation progress after knee arthroplasty surgery and the design of prostheses. Currently, measuring KCF is dependent on the data extracted ...
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Knee joint contact force (KCF) plays a significant role in the occurrence and progression of knee osteoarthritis (KOA) disease. KCF can be used in monitoring rehabilitation progress after knee arthroplasty surgery and the design of prostheses. Currently, measuring KCF is dependent on the data extracted from gait laboratories. The combination of artificial neural networks (ANNs) and wearable technology can overcome the limitations imposed by lab-based analysis in measuring KCF. Therefore, the present study aimed to investigate the potential of a fully-connected neural network (FCNN) in predicting the KCF via three inertial measurement unit (IMU) sensors attached to the pelvis, thigh, and shank segments. Ten healthy male volunteers participated in this study. The 3D marker trajectories and ground reaction forces (GRF) were captured at 200 Hz and 1000 Hz sampling frequencies during level-ground walking. Using a generic OpenSim model, the KCF was estimated through static optimization. The resultant KCF estimated by the musculoskeletal model was then used as the target of the neural network, while linear acceleration and 3D angular velocity data captured by three IMUs were considered as the network inputs. The network performance was investigated at intra- and inter-subject levels. Based on our findings, the proposed network of this study enables the prediction of KCF with 89% and 79% accuracy (based on the Pearson correlation coefficient) at the intra- and inter-subject levels, respectively. The results of this study promise the possibility of using IMU sensors in predicting KCF outside the lab and during daily activities.
Biomechanics / Biomechanical Engineering
Hadi Nickbakht; Seyyed Yousef Ahmadi Brooghani; Vahid Arbabi
Volume 16, Issue 2 , September 2022, , Pages 159-166
Abstract
In a varus knee, the load balance on two sides of the knee joint is disturbed and the stress applied to the medial side of the joint will be greater than that of a healthy knee. Such a case is often progressive and gradually leads to wear and pain. In this study, the finite element model for two 3D samples ...
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In a varus knee, the load balance on two sides of the knee joint is disturbed and the stress applied to the medial side of the joint will be greater than that of a healthy knee. Such a case is often progressive and gradually leads to wear and pain. In this study, the finite element model for two 3D samples of healthy knee joint and varus knee in standing position was generated from MRI images and after loading and solving the problem, the stress distribution status in menisci and cartilage is obtained for both modes. The obtained results show the difference in maximum stresses and the difference in the shape of stress distribution areas. The results also show that the maximum values of von Mises stress and also the contact pressure in the inner area of the knee for the varus knee are much higher values compared to a healthy knee. In the standing position, the maximum contact pressure in the inner area of the joint, under a 400 N load applied to the upper end of the femoral head, was obtained 4.527 and 7.821 MPa for a healthy knee and varus, respectively. For maximum values of von Mises stress, 2.821 and 6.501 MPa was obtained respectively. Due to the results and differences in stresses, the need for surgery to balance the stresses and loads on two sides of the knee is essential for a patient with varus knees. The amount of correction can be determined in addition to examining the joint geometry by examining the differences in stresses on both sides of the joint in a more accurate way.
Biomechanics / Biomechanical Engineering
Nima Sarrafzadeh Ghadimi; Farzan Ghalichi; Hanieh Niroomand-Oscuii; Nasser Fatouraee
Volume 15, Issue 4 , March 2022, , Pages 299-312
Abstract
Considering the common diseases that occur in the heart valves, it is possible that these valves can be replaced with artificial valves. This article examines different types of polymeric valves for the possibility of replacement in the human body. Different models are compared and the optimal valve ...
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Considering the common diseases that occur in the heart valves, it is possible that these valves can be replaced with artificial valves. This article examines different types of polymeric valves for the possibility of replacement in the human body. Different models are compared and the optimal valve is presented. For complete information, refer to the text of the article.
Biomechanics / Biomechanical Engineering
Mostafa Haj Lotfalian; Mohammad Hadi Honarvar
Volume 14, Issue 2 , July 2020, , Pages 133-142
Abstract
Margin of stability is a method to assess the dynamic stability in the clinic and laboratory, which is influenced by position and linear velocity of the center of mass (CoM). In this study, the stability factor was calculated by the margin of stability (MoS) method and was used as a cost function to ...
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Margin of stability is a method to assess the dynamic stability in the clinic and laboratory, which is influenced by position and linear velocity of the center of mass (CoM). In this study, the stability factor was calculated by the margin of stability (MoS) method and was used as a cost function to plan movement trajectory of sit to stand. 10 healthy young men were selected in this study and their sit to stand movement were filmed by Optitrack motion capture system. A two-dimensional and four-segment model was defined based on the governing equations of motion to calculate position of CoM, joints torque and using that in optimization process. After calculating the subject’s stability factor by MoS method, the time integral of MoS (C1), the maximum and minimum of MoS (C2) and the time integral of the square of MoS (C3) were defined as the cost functions. genetic algorithm was used to find the optimal model. To determine the quality of predicted trajectories and compare it with the subject’s pattern, root mean square error (RMSE) was used. According to the results of this study, a model which was optimized by C3, predicted the movement trajectory of subjects with 19 and 40 percent less error than C1 and C2 respectively.Nevertheless, none of the models could correctly reconstruct the subjects’ movement trajectory. In a nutshell, using MoS exclusively as a cost function, is not a good choice to predict and plane the trajectory of whole-body movements.
Biomechanics / Biomechanical Engineering
Hadi Taghizadeh
Volume 14, Issue 1 , May 2020, , Pages 23-30
Abstract
Determining mechanical properties of very soft tissues have been considered as a popular and challenging topic in biomechanics only in the last decades. In addition, these tissues do not have any weight-bearing functions, however, their mechanical characterization is important for designing new safety ...
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Determining mechanical properties of very soft tissues have been considered as a popular and challenging topic in biomechanics only in the last decades. In addition, these tissues do not have any weight-bearing functions, however, their mechanical characterization is important for designing new safety equipment, diagnosis and treatment of the diseases and tumors. Liver is one of the vital body organs that is highly porous and tearable and is highly susceptible to mechanical damage during accidents and minimally invasive surgeries. In this study, a set of uniaxial tension tests was performed on a bovine liver tissue. Linear elastic model in combination with the Bridgman correction method was utilized to determine the mechanical properties, i.e., Young’s modulus. An image processing software was also developed utilizing MS Visual Fortran language in order to obtain and track required geometric dimensions, i.e., radii of curvature, minimal sample radius in the necking zone, and probable detaching during the test session. Our experiments showed a tensile elastic modulus of 15.51±1.62 kPa for the samples (p < 0.05). Different amounts for elastic modulus of the liver have been reported in the literature. Hence, we conducted tension tests on samples with progressively increasing diameters. The changes in the sample diameter was in the range of 2.5 to 20 mm. In this way, the effect of sample diameter on elastic modulus was inquired. Our results indicate an inverse relation between elastic modulus and diameter in the tested zone. Such phenomena can be attributed to small sample size which is similar to the size of liver lobules (a few millimeters). Hence, samples with diameters in the range of lobule size cannot constitute a suitable representative element for the liver tissue. To obtain valid results the sample diameters should be more than three times that of the lobule.
Biomechanics / Biomechanical Engineering
Mahdi Bagheri Rouchi; Mehrdad Davoudi; Mohammad Parnianpour
Volume 13, Issue 2 , August 2019, , Pages 177-187
Abstract
According to the literature, changes in muscle activity patterns are considered as one of the causes of non-specific chronic low back pain. Recent studies have introduced muscle synergy as a valuable tool for analyzing how muscles work in body movements. In this way, a new study method is proposed for ...
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According to the literature, changes in muscle activity patterns are considered as one of the causes of non-specific chronic low back pain. Recent studies have introduced muscle synergy as a valuable tool for analyzing how muscles work in body movements. In this way, a new study method is proposed for modeling upper body and extracting time-varying muscle synergies in flexural motion of the waist. In this way, a new study method is proposed for modeling trunk and extracting time-varying muscle synergies in plane bending movements of lumbar flexion. Considering 18 effective muscles and function of the combined cost of the minimum jerk-energy, 24 different movements and their corresponding muscle patterns have been simulated. To evaluate the role of velocity, the pattern of muscle activity was divided into two parts: tonic, to overcome the gravity force, and phasic, proportional to the trunk movement velocity. In the following, three fast-reaching times of 0.75, 1, and 2 seconds were considered for each direction. The results showed that 77% of the lumbar muscle pattern of movement was achieved by four phasic synergies and four tonic synergies. The resulting synergies are quite influenced by the movement direction and velocity, so that each pair of phasic and tonic synergy is most effective in one of the main directions. On the other hand, the increase in velocity causes elevated amplitude coefficient and accelerated activation of phasic synergies compared to normal mode. Considering the 45° flexion combination with 30° left lateral bending, 77.2% of the muscle pattern of movement has been reconstructed using time-varying synergies. It can be argued that the use of muscle synergies expresses a good explanation for how muscles work in movement at different directions and velocities.
Biofluid Mechanics / Biofluids
Mohammad Ahmadi Alashti; Bahman Vahidi; Mahtab Ebad
Volume 13, Issue 1 , April 2019, , Pages 1-15
Abstract
The large surface area of the lung with its thin air-blood barrier is exposed to particles in the inhaled air. In this condition, if the inhaled pollutant aerosols are toxic, the particle-lung interaction may cause serious hazards and injuries on human’s health. On the otherhand, these interactions ...
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The large surface area of the lung with its thin air-blood barrier is exposed to particles in the inhaled air. In this condition, if the inhaled pollutant aerosols are toxic, the particle-lung interaction may cause serious hazards and injuries on human’s health. On the otherhand, these interactions are also used for drug delivery to human’s body. In either case, an accurate estimation of dose and sites of deposition in the respiratory tract is fundamental for understanding mechanobiology of these deseases. Obtaining in vivo data of particle transportation in the human lung experimentally is often difficult. But, computational fluid-particle dynamics (CFPD) has provided the possibility to gain aerosol transportion data in realistic airway geometries. Aerosols deposition in the human lung mainly occurs due to combination of inertial impaction, gravitational sedimentation and diffusion. For particles with aerodynamic size of 0.5 to 5 micron and in inhalation state of lung, the main mechanisms of particle deposition in distal parts of human’s respiratory system are sedimentation, due to gravity and convective transfer due to wall movement. In this study, deposition of particles in distal part of human respiratory system, specifically 18th generation, has been modeled for two gravity conditions, normal and absent gravity, by assuming isotropic displacements on the walls and with the rate of 1 (mg/sec) for particle input. By analyzing the results, it was determined that the amount of particle deposition in distal airways reduces a great amount by omitting the effect of gravitational force because, particles smaller than 5 micron can penetrate into that airways. Particles with the diameter of 5 micron deposit under the effect of inertial impact, whereas this mechanism occurs mostly in airways with large and medium diameters and also, by sedimentation which occurs in the distal lung.
Biomechanics / Biomechanical Engineering
Mahdieh Mosayebi; Afsaneh Mojra
Volume 13, Issue 1 , April 2019, , Pages 31-44
Abstract
Intervertebral disc (IVD) provides flexibility and shock absorption for the spine in the load transmission procedure. Disc degeneration may occur as a result of aging and inappropriate types of loading. Assessing biomechanical parameters of intact IVD in comparison to the degenerated disc with different ...
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Intervertebral disc (IVD) provides flexibility and shock absorption for the spine in the load transmission procedure. Disc degeneration may occur as a result of aging and inappropriate types of loading. Assessing biomechanical parameters of intact IVD in comparison to the degenerated disc with different grades of degeneration can facilitate the detection procedure and planning for suitable therapeutic treatment. In the present study, a real three-dimensional model of cercival IVD ( - with adjacent vertebrae is constructed by using computed tomography (CT-scan) images. In order to accurately define mechanical properties, the disc and the vertebrae are modelled as poroviscoelastic and poroelastic materials, respectively. A porous medium approach is adopted to consider the considerable water content of both media alongside the solid matrix. For the solid phase of the IVD, the related viscoelastic parameters are extracted from an experimental test on a sheep lumbar intervertebral disc and stress vs. time data are fitted to the generalized Maxwell model with two Maxwell arms. By employing the finite element method, time-dependent response of the intact IVD and three different levels of the degenerated IVD (mild, moderate and severe) are studied in a relaxation test. Results indicate that during relaxation procedure, intradiscal fluid velocity decreases as a result of disc degeneration. This may oppositely affect the flexibility of IVD in the load bearing. It is also observed that stress relaxation of the severe degenerated IVD almost increases up to 16% relative to the intact IVD. Assessing the amount of disc bulging under load application shows enhancement for the degenerated disc compared to the intact disc.
Biomechanics / Biomechanical Engineering
Maedeh Najafi Ashtiani; Mohammad Reza Asghari Oskoei; Mohammed Najafi Ashtiani
Volume 12, Issue 4 , January 2019, , Pages 331-340
Abstract
Balance is essential for human daily activities. Standing on an unstable platform requires continuous effort of the neuro-musculoskeletal system. Cognitive interference and support surface perturbation may cause loss of balance. The aim of this study is to evaluate the ability of stability provision ...
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Balance is essential for human daily activities. Standing on an unstable platform requires continuous effort of the neuro-musculoskeletal system. Cognitive interference and support surface perturbation may cause loss of balance. The aim of this study is to evaluate the ability of stability provision of individuals while standing in different levels of postural and cognitive difficulty. To this end, twelve healthy young women were participated in six levels (three levels of support surface × two levels of cognitive intereference). Three levels support surface were standing on a firm surface, unstable platform surface with and without spring support. Two levels of attentional cognitive involvements were considered with or without questions by presenting on a curtain and asking to response by a yes/no joystick. Motion analysis was used to measure joint angles by capturing body movements in the sagittal plane by a high-speed camera and active markers. To quantitatively investigate the stability, two linear (pathlength, root mean square) and two nonlinear (approximate entropy, fractal dimension) metrtics were calculated. Results showed that the ankle mechanism plays a more prominent role in keeping balance than the knee and hip joint mechanisms. Merely the approximate entropy indicated significant differences between the postural difficulty levels. Also, the mediocre level of support surface perturbation (spring-supported unstable platform) revealed multi-joint collaboration between the mechanisms. The inconsistence between postural and cognitive difficulty levels might vanish the role of cognitive questions in the present study. Therefore, considering consistent postural and cognitive tasks may highlight the effects of cognitive involvements on standing.
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 / Biomechanical Engineering
Mohsen Rabbani; Mahmood Reza Sadeghi; Parisa Golmohammadi; Amin Deyranlou
Volume 11, Issue 2 , June 2017, , Pages 137-151
Abstract
The atherosclerosis disease is the most prevalent illness that occurs in large or medium size arteries. The most important consequence of this disease is creation of arterial platelets in places where in addition to artery damages; the density of materials such as low density lipoprotein (LDL) is being ...
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The atherosclerosis disease is the most prevalent illness that occurs in large or medium size arteries. The most important consequence of this disease is creation of arterial platelets in places where in addition to artery damages; the density of materials such as low density lipoprotein (LDL) is being increased. The produced platelets not only block appropriate blood delivery to downstream fibers but also in advanced stages, rubbing or tearing platelet could bring about clot and eventually heart or brain stroke. In this research, in order to review the procedure of LDLs accumulation within lumens and arterial wall, numerical simulation of LDL particles mass transport by using several layer model and diffusion coefficient depending on shear rate are used. Arteries’ walls are assumed to be porous and rigid. In this study, Navier–Stokes equations, mass transport, and Darsi have been solved by numerical methods with regarding to non-Newtonian behavior of blood in lumens and different layers of vessel’s wall. In this article, the impacts of diffusion coefficient being constant or variable, impact of non-Newtonian behavior of blood, impact of non-Newtonian behavior of plasma and impact of blood pressure on the amount of LDL accumulation in lumen and layers of carotid artery are reviewed. The results indicate that diffusion coefficient variation in arterial lumen and non-Newtonian behavior of plasma within the arterial wall could affect significantly on LDL accumulation. In addition, increasing blood pressure not only increases LDL accumulation on interface of blood and arterial wall but also increases the accumulation within arterial wall layers and consequently the artery is more susceptible to atherosclerosis development.
Biomechanics / Biomechanical Engineering
Mehran Ashrafi; Farzan Ghalichi; Behnam Mirzakouchaki
Volume 10, Issue 2 , August 2016, , Pages 113-121
Abstract
Nowadays, the use of dental implants in people with osteoporosis is increasing. The consequences of osteoporosis can be important to the success of osteosynthesis devices, prosthetics and dental implants. Using bisphosphonates, which with impressing bone remodeling and decreasing bone catabolic activity ...
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Nowadays, the use of dental implants in people with osteoporosis is increasing. The consequences of osteoporosis can be important to the success of osteosynthesis devices, prosthetics and dental implants. Using bisphosphonates, which with impressing bone remodeling and decreasing bone catabolic activity lead to increase bone formation can be used as a solution to increase bone density in patients with osteoporosis, which normally osteoporosis is considered as a risk to the acceptance of dental implants by alveolar bone. This study examines the effect of different concentrations of bisphosphonates on bone remodeling. By improving bone remodeling model and taking into account the drug concentration effect on bone resorption, drug effect will be considered. For this purpose, 5, 10 and 20 mg of alendronate per implant and control sample are simulated for a period of 360 days. By comparing the results with control sample, with increasing the drug dose, decrease in bone stress, increase in bone density and thus increase in young's modulus was observed.
Biomechanics / Biomechanical Engineering
Aminreza Noghrehabadi; Mohammad Hosein Heidarshenas; Reza Bahoosh
Volume 10, Issue 2 , August 2016, , Pages 123-136
Abstract
A two-dimensional-in-space mathematical model of amperometric micro biosensors with selective and perforated membranes has been proposed and analyzed. The model involves the geometry of micro or nano meter holes partially or fully filled with an enzyme. The model is based on a system of the reaction-diffusion ...
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A two-dimensional-in-space mathematical model of amperometric micro biosensors with selective and perforated membranes has been proposed and analyzed. The model involves the geometry of micro or nano meter holes partially or fully filled with an enzyme. The model is based on a system of the reaction-diffusion equations containing a nonlinear term related to the Michaelis-Menten enzymatic reaction. In this study, in order to generate general equation, first, dimensionless parameters are introduced and then by replacing them into governing equation are converted to dimensionless equations.The general equations have been solved numerically in 2D space.. Using numerical simulation of the biosensor action, the influence of the geometry of the holes as well as of the filling level of the enzyme in the holes on the biosensor response was investigated. For this purpose three different geometries including cylindrical, upright circular and downright circular cone for cavities are considered and the impact of these geometries on the response of the biosensor in different levels of enzyme are obtained. Biosensor's respond based on rate of enzyme level variations to slope of the cone variations are determined. In the biosensor, as the level of enzyme rises in all three geometries, the biosensor output current increases. Under the same conditions, the sensitivity of biosensor in upright circular cone is more than the other two geometries and increases with a decrease in conical gradient. As long as the enzymatic properties are the same, the more biosensor's number, the more sensitivity.Moreover, a concept known as reduced dimensionless current is introduced by providing and calculating dimensionless current in the biosensor.
Biomechanics / Biomechanical Engineering
Hasan Sayyadi; Seyed Hamid Zare
Volume 9, Issue 3 , December 2015, , Pages 253-265
Abstract
The study focuses on the optimal design of a hybrid rotary MR with waveform boundary T-shaped rotor as prosthesis knee. In the biomechanical prosthesis knee MR fluid to create a variable braking torque depending on the magnetic field is used. By applying a magnetic field, the viscosity of the fluid is ...
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The study focuses on the optimal design of a hybrid rotary MR with waveform boundary T-shaped rotor as prosthesis knee. In the biomechanical prosthesis knee MR fluid to create a variable braking torque depending on the magnetic field is used. By applying a magnetic field, the viscosity of the fluid is actively controlled to achieve the desired braking torque. After a brief description of the configuration of the rotary damper; achievable braking torque formulas is presented. In the following, optimization problem aims to find the optimal geometry in order to maximize the on-state braking torque while off-state torque and weight are within the permitted range. Depending on the application of the referred damper, the maximum braking torque, minimizing torque at off-state, minimizing damper’s weight and have uniform flux density are under consideration. The results of the optimized rotary damper are compared with the reference brake. Then, the performance improvement of the optimized MR brake is discussed.
