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Journal of Long-Term Effects of Medical Implants (10506934) 35(2)pp. 33-39
Temporomandibular joint (TMJ) disorders significantly impact orofacial health and quality of life, necessitating effective interventions. This study presents a comprehensive finite element analysis (FEA) focusing on the design and material modifications of temporomandibular joint implants, with the aim of improving their long-term stability and performance. Accurate mandible models extracted from Computational Tomography (CT) scans were used to create three variations of implants, each attached using varying screw configurations ranging from 2 to 5 for each analysis. The variations included implants without dimples, implants with 10% dimples, and implants with 20% dimples. The FEA considered material properties of Titanium and Ti-Nb-Zr alloy for the implants. The FEA results revealed that for 10% dimples models, equivalent stress was reduced by 6.25% with two screws fixation and further decreased by 14.28% with three screws, irrespective of the implant volume, reaffirming the significance of screw fixation. The model secured with three screws exhibited the least amount of stress for both titanium and zirconium alloys and dimple implants showed promise in reducing stress levels, particularly in low bone density conditions. These findings not only underscore the potential advantages of dimple implants in facilitating bone in growth and stability at the bone-implant interface but also highlight the pivotal role of implant dimples in modulating stress levels. The study contributes valuable insights for future advancements in TMJ implantology, offering potential optimizations for implant design and clinical outcomes. © 2025 by Begell House, Inc.
Rahmani, A. ,
Rajaeirad, M. ,
Roy, S. ,
Jamshidi, N. ,
Khorsandi, M. ,
Feizkhah, A. pp. 147-152
Dental implant success is crucial for patient wellbeing, yet implant loosening remains a significant concern, particularly in compromised bone quality. This study aims to address this issue by evaluating the performance of various implant materials across different bone qualities. We compare traditional titanium implants with carbon fiber-reinforced polyetheretherketone (CFR-PEEK) and CFR-PEEK reinforced with varying concentrations of hydroxyapatite (HAP). A threedimensional finite element model of a mandibular segment was employed to simulate implant behavior in bone qualities ranging from very weak to very strong. Stress distribution, strain, and interface characteristics were analyzed for each implant material and bone quality combination. Results showed that CFR-PEEK exhibited the most dynamic behavior, with a 1 0. 1 4% stress reduction in cancellous bone from very weak to very strong bone quality. Titanium maintained a consistent 703 0% implant-bone stress distribution across all bone qualities. In very strong bone, all materials except titanium induced similar cancellous bone strains. CFR-PEEK with 20% HAP emerged as a balanced option, offering a moderate 6.94% stress reduction across bone qualities. In conclusion, while CFRPEEK demonstrates advantages in stress distribution and bone stimulation, particularly in higher quality bone, titanium provides more consistent performance across varying bone qualities. The optimal implant material may depend on patientspecific bone quality, with CFR-PEEK + 2 0% HAP offering a promising balance for diverse clinical scenarios. © 2024 IEEE.
Zadeh-posti, M.H. ,
Kamal, Z. ,
Rajaeirad, M. ,
Einafshar, M.M. ,
Jamshidi, N. pp. 219-224
Adolescent Idiopathic Scoliosis (AIS) is a condition marked by an abnormal curvature of the spine. This study aims to model AIS using computational techniques to analyze varying bone densities within vertebrae under different muscle paralysis conditions. The aim is to investigate how unilateral muscle paralysis affects bone density and to model conditions similar to AIS. A three-dimensional model of the L2 vertebra was created using Mimics and 3-matic software for segmentation and meshing. The model was imported into ABAQUS for further integration and assignment of properties. The bone remodeling algorithm was applied over 12 months, simulating the intact scoliosis (IS) condition. Loading conditions specific to IS were applied, and three scenarios of muscle paralysis were modeled: longissimus pars thoracic (LGPT) muscle paralysis, multifidus lumborum (MFL) muscle paralysis, and both muscles' paralysis. The current study found variable bone density and Young's modulus distributions for cancellous and cortical bones in the AIS model. Trabecular bone density varied between 0.297 and 0.317g/cm3, with Young's modulus ranging from 99.61 to 115.83 MPa. Cortical bone density ranged from 1.466 to 1.665 g/cm3, while Young's modulus was between 11,794 and 16,110 MPa. The highest von Mises stress was observed in the cortical bone, particularly in the concave region, which is under higher compression in AIS patients than healthy spines. The results of this study support Frost's mechanostat theory, suggesting that uneven loading leads to higher bone density on the concave side of scoliotic vertebrae. The study demonstrates the feasibility of using computational models to simulate AIS and highlights the significance of muscle conditions on bone remodeling and stress distribution in vertebrae. © 2024 IEEE.
Background: During bone drilling, a common procedure in clinical surgeries, excessive heat generation and drilling force can cause damage to bone tissue, potentially leading to failure of implants and fixation screws or delayed healing. With this in mind, the aim of this study was to evaluate the efficiency of ultrasonic-assisted drilling compared to conventional drilling as a potential method for bone drilling. Methods: This study examined optimal drilling parameters based on previous findings and investigated both cortical and cancellous bone. In addition to evaluating drilling force and temperature elevation, the effects of these factors on osteonecrosis and micro-crack formation were explored in ultrasonic-assisted and conventional drilling through histopathological assessment and microscopic imaging. To this end, three drilling speeds and two drilling feed-rates were considered as variables in the in vitro experiments. Furthermore, numerical modeling provided insight into temperature distribution during the drilling process in both methods and compared three different vibration amplitudes. Results: Although temperature elevations were lower in the conventional drilling, ultrasonic-assisted drilling produced less drilling force. Additionally, the latter method resulted in smaller osteonecrosis regions and did not produce micro-cracks in cortical bone or structural damage in cancellous bone. Conclusions: Ultrasonic-assisted drilling, which caused less damage to bone tissue in both cortical and cancellous bone, was comparatively more advantageous. Notably, this study demonstrated that to determine the superiority of one method over the other, we cannot rely solely on temperature variation results. Instead, we must consider the cumulative effect of both temperature elevation and drilling force. © 2024 The Authors
International Urogynecology Journal (09373462) 34(2)pp. 571-580
Introduction and hypothesis: This study aims to develop a fluid-structural interaction (FSI) method to pinpoint the effects of pressure changes inside the bladder and their impact on the supporting structure and the urethra mobility. Methods: A physiological model of the nulliparous female pelvis, including the organs, supportive structures, and urine, was developed based on magnetic resonance images. Soft tissues with nonlinear hyperelastic material characteristics were modeled. The Navier-Stokes equations governing the fluid flow within the computational domain (urine) were solved. The urine and soft tissue interactions were simulated by the FSI method. The vesical pressure and its impact on the urethral mobility and supportive structures were investigated during the Valsalva maneuver. Moreover, the simulation results were validated by comparing with a urodynamic test and other research. Results: The results demonstrated that the vesical pressure simulated by the FSI method could predict the nonlinear behavior of the urodynamic test pressure. The urethra retropubic bladder neck and the bladder neck-pubic bone angle changed 58.92% and -55.76%, respectively. The retropubic urethral length distance changed by -48.74%. The error compared to the statistical results of other research is < 5%. Conclusions: The total deformation and mobility of the urethra predicted by the FSI model were consistent with clinical observations in a subject. The urethra supports dependence on the tissues' mechanical properties, interaction between the tissues, and effect of urine fluid inside the bladder. This simulation effectively depicts the patterns of urethra mobility, which provides a better understanding of the behavior of the pelvic floor. © 2022, The International Urogynecological Association.
Journal of Tissue Engineering and Regenerative Medicine (19327005) 16(9)pp. 812-824
Menisci are fibrocartilaginous structures in the knee joint with an inadequate regenerative capacity, which causes low healing potential and further leads to osteoarthritis. Recently, three-dimensional (3D) printing techniques and ultrasound treatment have gained plenty of attention for meniscus tissue engineering. The present study investigates the effectiveness of low-intensity pulsed ultrasound stimulations (LIPUS) on the proliferation, viability, morphology, and gene expression of the chondrocytes seeded on 3D printed polyurethane scaffolds dip-coated with gellan gum, hyaluronic acid, and glucosamine. LIPUS stimulation was performed at 100, 200, and 300 mW/cm2 intensities for 20 min/day. A faster gap closure (78.08 ± 2.56%) in the migration scratch assay was observed in the 200 mW/cm2 group after 24 h. Also, inverted microscopic and scanning electron microscopic images showed no cell morphology changes during LIPUS exposure at different intensities. The 3D cultured chondrocytes under LIPUS treatment revealed a promotion in cell proliferation rate and viability as the intensity doses increased. Additionally, LIPUS could stimulate chondrocytes to overexpress the aggrecan and collagen II genes and improve their chondrogenic phenotype. This study recommends that the combination of LIPUS treatment and 3D hybrid scaffolds can be considered as a valuable treatment for meniscus regeneration based on our in vitro data. © 2022 John Wiley & Sons Ltd.
Amiri, F. ,
Babaei, M. ,
Jamshidi, N. ,
Agheb, M. ,
Rafienia m., M. ,
Kazemi, M. International Journal of Biological Macromolecules (01418130) 203pp. 610-622
The meniscus has inadequate intrinsic regenerative capacity and its damage can lead to degeneration of articular cartilage. Meniscus tissue engineering aims to restore an injured meniscus followed by returning its normal function through bioengineered scaffolds. In the present study, the structural and biological properties of 3D-printed polyurethane (PU) scaffolds dip-coated with gellan gum (GG), hyaluronic acid (HA), and glucosamine (GA) were investigated. The optimum concentration of GG was 3% (w/v) with maintaining porosity at 88.1%. The surface coating of GG-HA-GA onto the PU scaffolds increased the compression modulus from 30.30 kPa to 59.10 kPa, the water uptake ratio from 27.33% to 60.80%, degradation rate from 5.18% to 8.84%, whereas the contact angle was reduced from 104.8° to 59.3°. MTT assay, acridine orange/ethidium bromide (AO/EB) fluorescent staining, and SEM were adopted to assess the behavior of the seeded chondrocytes on scaffolds, and it was found that the ternary surface coating stimulated the cell proliferation, viability, and adhesion. Moreover, the coated scaffolds showed higher expression levels of collagen II and aggrecan genes at day 7 compared to the control groups. Therefore, the fabricated PU-3% (w/v) GG-HA-GA scaffold can be considered as a promising scaffold for meniscus tissue engineering. © 2022
Journal of Orthopaedic Surgery and Research (1749799X) 15(1)
Background: During drilling of bone, which is common in clinical surgeries, heat generation increases local temperature in the drilling site. Transmission of excessive heat to the surrounding bone tissue can cause thermal osteonecrosis. Consequently, it may lead to failure of implants and fixation screws or delay in healing process. Using cooling is a method for limiting temperature elevation. Materials and methods: In this study, through comparing three conditions of drilling without cooling, external cooling with normal saline, and external cooling with OpSite spray, the efficiency of OpSite as coolant is studied. In this regard, 2 drill bit diameters, 3 drilling speeds, and 3 drilling feed-rates are considered as drilling variables in the experiments. Results: For the whole experiments, while cooling with normal saline resulted in lower maximum temperatures than without cooling condition, OpSite had even better results and limited the temperature elevation during drilling of bone efficiently. Conclusion: OpSite spray, which has lower infection risks than normal saline on one hand and lower maximum temperature rise with all combinations of drilling parameters on the other hand, can be considered in clinical surgeries for cooling applications. © 2020 The Author(s).
Fibers and Polymers (12299197) 21(3)pp. 636-645
Compression garments due to their numerous medical applications have been recently attracted to be mechanically analyzed for their compression mechanism. Predicting the pressures applied to musculoskeletal tissues supported by these garments is a good solution for doing such analyzing which could be simply achieved by the help of finite element method. In this paper, the main aim was investigating the structural effect of knitted compression garments used for supporting the body lower-limb musculoskeletal system. Compression garments of weft knitted rib structure containing elastane yarn were prepared according to the leg’s dimensions of a healthy 27-year old person. Using Kikuhime measuring device, experimental values of the applied pressure were measured in order to be compared with theoretical results. For developing a three-dimensional biomechanical model for the leg system supported by compression garment, images form computed tomography scanning methodology was used. Tensile properties of an elastane yarn as the basis for studying the compression garment’s mechanical behavior were experimentally measured and then simulated in Abaqus software as a linear viscoelastic material. The results were then applied to multi-scale modeling technique in order to simulate mechanical behavior of the knitted fabric and the compression garment thereof. Combination of both experimental and theoretical results was applied to simulate interactions between the leg and the compression garment. The results indicated that the pressure values simulated by finite element method were predicted with the maximum mean error of 19.64 % and total error mean of 12.29 % compared to experimental results. Small difference between the measured and simulated values was observed for tibia and fibula because of their low soft-tissue volume. The proposed model enables the specialists to present compression garments based on the patient’s needs and physician prescription which generate the optimal treatment. © 2020, The Korean Fiber Society.
Journal of Industrial Textiles (15308057) 49(10)pp. 1389-1410
Cushioning pads alleviate the effects of mechanical stress on the human body due to impacts and daily activities. One relevant application for such pads is orthopedic insoles used for diabetic foot to improve energy absorption and reduce stress gradient by using suitable materials and structures. This article considers a novel design that improves the energy absorption capabilities of cushioning pads. Experiments were conducted to evaluate the properties of the designed weft knitted spacer fabrics. Six groups of samples were knitted in which steel, polyamide, and shape memory alloy materials were utilized as spacer monofilament. Stress–strain, energy absorption and efficiency diagrams were obtained following the quasi-static compression tests carried out on the samples. Three investigation groups were adopted to evaluate the effect of the spacer monofilament material, diameter, and slope on energy absorption capacity. It was determined that shape memory alloy monofilament with 0.1 mm diameter was the optimum configuration to be utilized as spacer yarn in a typical 3D weft knitted fabric. It was also concluded that higher-inclined spacer monofilament in spacer fabric was the optimum choice for knitting cushioning pads as it absorbed more energy. The energy absorption capacity of the optimum design of spacer fabric obtained in this study, increased by a factor of 2.4 compared with commercial polyamide pads. This design can be utilized in any cushioning pad exposed to high mechanical stress due to impact, sports and daily activities. © The Author(s) 2018.
The knee as a vital organ in the human body skeleton is one of the largest joints. In recent years, there have been a variety of therapies offered to improve the efficiency and performance of an implanted prosthetic knee joint. Knee replacement is considered as one of the most common and effective treatments which is technically known as knee arthroplasty. Various factors could affect the mechanical behavior of knee arthroplasty, including the patients' sex, physical, and bone characteristics as well as prosthesis type, structure, and geometry. The very recent advances in arthroplasty have enabled the orthopedists to achieve more desirable results by following the standards offered for prosthesis considering the anatomical geometry and material structure. Knee prosthetic implants with and without stem are the two prevalent types that orthopedists utilize for the joint replacement. In this case study, a real knee joint geometry is reconstructed using the CT images and MIMICS software. The knee arthroplasty model was then imported to the ABAQUS to perform FE analysis on the two aforementioned types of prosthesis. According to the results, the prosthesis with stem causes more stress on the joint components in the vicinity of the implantation region but will allow the knee joint to have a greater angular displacement with lower stress. © 2020 IEEE.
Journal of Mechanics in Medicine and Biology (17936810) 19(6)
Total hip Arthroplasty is one of the most common surgeries in elderly people around the world. In spite of many successful cases, a few failures are still reported, a significant number of which relates to the effects of stress shielding. Many scientists have been working on solving this problem by enhancing the material and/or the geometry of the hip prostheses' stems. For example, hollow-stemmed hip prostheses have been designed and tested. In this study, 30 hollow-stemmed samples were designed which were different in terms of geometry and dimension of their holes as well as the materials defined for them. Then, they were tested through finite element modeling along with validating and verifying the results using experimental and convergence tests. The results including displacements, maximum stress values and consequent safety factors were compared based on the reactions of the samples against various static loads including the loads predefined by ISO 7206-4 as well as the loads which had been previously obtained. D2 designs show the least stiffness compared to other designs. Designs with 132.66mm2 hole area are the most promising layouts for reducing weight and providing the most amount of medullary space for revascularization of the femur. In spite of designs which predictably help revascularization more than D2 designs, these designs which are of the multi-hole patterns seemed to represent the best outcomes in terms of preventing stress shielding and consequently the best pattern for creating holes in the stem according to the precedence of stress shielding over other problems. The results prove the possibility of representing a promising structure which helps to reduce the weight, stress shielding and the lack of revascularization of the femur. © 2019 World Scientific Publishing Company.
Polish Annals of Medicine (12308013) 25(1)pp. 17-20
Introduction: Pressure vest is usually used as a training intervention for the treatment of autistic children by medical experts. This article assessed the effect of pressure vest on attention and involuntary behaviors of children with autism. Aim The aim of this study is to expand the pressure vest therapy as a new non-invasive method to treat the autism spectrum disorder. Material and methods: Pressure vest have cells dilated to apply pressure to the body and an air compressor manually adjustable for proper functioning. It is needed to apply pressure in a different way to enter some dynamic pressure that has a characteristic rhythmic massage. In this study, we used an alternative treatment plan for five children with autism within seven days of seven weeks. At first, the vest was worn to the baby and then a series of tasks and common games were performed. The Micro had three different programs to control valves of pressure vest. Re sul t s and discussion: Children in most cases did the exercises and assignments with interest and had more patience. Assessing four main parameters including the focus, anger, learning and speaking in children indicates that at the end of the seven-weak course, the behavior of children has improved in the form of a reduction in the anger level and the improvement of speaking, learning and focus. The device had an acceptable performance in the prevention of sudden behaviors. The major advantage of these vests were increasing focus and concentration, enhancing comprehension and learning and reducing hyperactivity. Conclusions: Further work with a larger database of subjects and different psychological evaluation methods is required to confirm our findings. The Micro three different programs to control valves of pressure vest had no significant effects. © 2018 Polish Annals of Medicine.
Computer Methods in Biomechanics and Biomedical Engineering (14768259) 21(3)pp. 201-207
The purpose of this simulation study was to analyze the effect of variation in Knee-Ankle-Foot-Orthosis stiffness on the joint power and the energy cost of walking. The effect of contractile tissue was simulated using linear elastic spring and viscous dampers in knee and ankle joints. Then, joint angles, ground reaction force, were collected from Twenty chronic hemiparesis subjects (15 males and 5 females) and twenty control subjects (14 males and 6 females), and spring stiffness were considered as the inputs. In this new study, the generated muscle torques were optimized by changing the stiffness as the desired output in the mathematical model attained by the MATLAB SimMechanics toolbox. Finally, the simulated mathematical model was introduced as an appropriate substitute in obtaining the optimized stiffness with a more convenient and efficient designed orthosis. © 2018 Informa UK Limited, trading as Taylor & Francis Group.
Journal of Mechanics in Medicine and Biology (17936810) 17(8)
The vertebroplasty (VP) and kyphoplasty (KP) are two minimally invasive surgeries using cement augmentation to treat the osteoporotic vertebrae in elderlies in order to relieve pain and prevent the continuation of microfractures. Biomechanists have always tried to assess the mechanical behavior of vertebrae after cement augmentation by using both the experimental and theoretical methods such as finite element modeling (FEM). In this study, 31 related articles using FEM in analyzing the VP and KP have been reviewed. This study included two main categories of spinal load distribution and tension in vertebrae after the VP and KP operations. This could be obtained by conducting FEM on the whole spine or other sectors of it such as intervertebral disc (IVD) or end plates (EPs). This study also referred to articles predicting the probability of adjacent fractures following VP and KP. The most common software employed in FEM was ABAQUS, applied for static and dynamic loads' analyses. It was found that most of the reviewed articles adopted reverse engineering techniques by converting 2D computed tomography (CT) scan images into 3D reconstructed models. The material properties were generally taken from the literature. In more than 80% of studies, the model geometry was based on CT data of the spine. Almost 45% of the studies have attempted to compare the simulated vertebra after augmentation with experimental results taken from the literature (5% of the reviewed articles) or their own experimental tests (40% of the reviewed articles). © 2017 World Scientific Publishing Company.
Tehran University Medical Journal (17357322) 75(2)pp. 120-125
Background: Application of Hybrid 6 degrees of freedom fixation could lead to space motion in each 3 anatomic plates together and decrease the time of complex deformities correction. This study is an investigation on the function of hybrid external fixation and the influence of it on decreasing the treatment time. About this case utilize of Ortho- SUV Frame (OSF) system is explained for the first time in Iran and report of its novel. These robotic systems are divided into two groups: active and passive, about active system all movements are done by actuators in joints and links. And in passive, the system needs an operator or patient to actuates Sturats by hand. Methods: The femur bone has been investigated was nonunion with deformity in sagittal, frontal and transversal planes. Ilizarov external fixation was applicate firstly, with this condition that the OSF systems jacks were replaced instead of simple rods in side of fracture. Software work was done on February of 2016 in Ayatollah Taleghani Hospital, Tehran, Iran. Fractures were happened in a car accident and some other operating were perforemed for this patient without any result. Results: The correction of studied deformity needs 3 planar moving. Acting this movement by Ilizarov requirements 33 mm displacement in frontal plane, 12 mm horizontal distraction and 48 mm displacement in sagittal plane. Due to the rate of correction in Ilizarov which is 1 mm per day, this bone needs 93 days for general correction and three times changing in shape of rings connections. While, by using the hybrid external fixation, all displacements were corrected in 46 days and first connection had supported all planes. Conclusion: According to that the decreasing of treatment time is one of the main goal, the hybrid external fixation systems could be an appointment choice in complex deformities and replaced with some common fixation. In addition to, using of updated software increases the accuracy of displacement. © 2015 Tehran University Medical Journal TUMS Publications. All Rights Reserved.
World Journal of Orthopedics (22185836) 8(11)pp. 829-835
AIM To reduce post treatments of kyphoplasty, as a common treatment for osteoporotic vertebrae. METHODS This study suggests a new method for treating vertebrae by setting the hexagonal porous structure instead of the rigid bone cement mass in the kyphoplasty (KP). The KP procedure was performed on the fresh ovine vertebra of the level L1. Micro finite element modeling was performed based on micro computed tomography of ovine trabecular cube. The hexagonal porous structure was set on one cube instead of the bone cement mass. For the implant designing, two geometrical parameters were considered: Spacing diameter and thickness. RESULTS The results of micro finite element analyses indicated the improvement in the mechanical behavior of the vertebra treated by the hexagonal porous structures, as compared to those treated by vertebroplasty (VP) and KP under static loading. The improvement in the mechanical behavior of the vertebra, was observed as 54% decrease in the amount of maximum Von Misses stress (improvement of stress distribution), in trabecular cube with embedded hexagonal structure, as compared to VP and KP. This is comparable to the results of the experimental study already performed; it was shown that the improvement of mechanical behavior of the vertebra was observed as: 83% increase in the range of displacements before getting to the ultimate strength (increasing the toughness) after setting hexagonal pearls inside vertebrae. Both the material and geometry of implant influenced the amount of Von Mises stress in the structure. CONCLUSION The new proposed method can be offered as a substitute for the KP. The implant geometry had a more obvious effect on the amount of Von Mises stress, as compared to the implant material. © The Author(s) 2017.
Australasian Physical and Engineering Sciences in Medicine (18795447) 40(1)pp. 137-144
Exoskeleton is a walking assistance device that improves human gait cycle through providing auxiliary force and transferring physical load to the stronger muscles. This device takes the natural state of organ and follows its natural movement. Exoskeleton functions as an auxiliary device to help those with disabilities in hip and knee such as devotees, elderly farmers and agricultural machinery operators who suffer from knee complications. In this research, an exoskeleton designed with two screw jacks at knee and hip joints. To simulate extension and flexion movements of the leg joints, bearings were used at the end of hip and knee joints. The generated torque and motion angles of these joints obtained as well as the displacement curves of screw jacks in the gait cycle. Then, the human gait cycle was simulated in stance and swing phases and the obtained torque curves were compared. The results indicated that they followed the natural circle of the generated torque in joints with a little difference from each other. The maximum displacement obtained 4 and 6 cm in hip and knee joints jack respectively. The maximum torques in hip and knee joints were generated in foot contact phase. Also the minimum torques in hip and knee joints were generated in toe off and heel off phases respectively. © 2016, Australasian College of Physical Scientists and Engineers in Medicine.
CiOS Clinics in Orthopedic Surgery (20054408) 9(4)pp. 480-488
Background: The traction bed is a noninvasive device for treating lower back pain caused by herniated intervertebral discs. In this study, we investigated the impact of the traction bed on the lower back as a means of increasing the disc height and creating a gap between facet joints. Methods: Computed tomography (CT) images were obtained from a female volunteer and a three-dimensional (3D) model was created using software package MIMICs 17.0. Afterwards, the 3D model was analyzed in an analytical software (Abaqus 6.14). The study was conducted under the following traction loads: 25%, 45%, 55%, and 85% of the whole body weight in different angles. Results: Results indicated that the loading angle in the L3–4 area had 36.8%, 57.4%, 55.32%, 49.8%, and 52.15% effect on the anterior longitudinal ligament, posterior longitudinal ligament, intertransverse ligament, interspinous ligament, and supraspinous ligament, respectively. The respective values for the L4–5 area were 32.3%, 10.6%, 53.4%, 56.58%, and 57.35%. Also, the body weight had 63.2%, 42.6%, 44.68%, 50.2%, and 47.85% effect on the anterior longitudinal ligament, posterior longitudinal ligament, intertransverse ligament, interspinous ligament, and supraspinous ligament, respectively. The respective values for the L4–5 area were 67.7%, 89.4%, 46.6%, 43.42% and 42.65%. The authenticity of results was checked by comparing with the experimental data. Conclusions: The results show that traction beds are highly effective for disc movement and lower back pain relief. Also, an optimal angle for traction can be obtained in a 3D model analysis using CT or magnetic resonance imaging images. The optimal angle would be different for different patients and thus should be determined based on the decreased height of the intervertebral disc, weight and height of patients. © 2017 by The Korean Orthopaedic Association.
Rafiaei, M. ,
Arazpour, M. ,
Bahramizadeh, M. ,
Farahmand, F. ,
Jamshidi, N. ,
Samadian, M. Journal of Prosthetics and Orthotics (10408800) 29(4)pp. 177-182
Background The aim of this study was to develop a new stance control knee-ankle-foot orthosis (SCKAFO) and determine its efficacy on specific spatiotemporal and kinematic parameters. Method Seven healthy volunteer subjects participated in this study. After orthotic gait training, subjects participated in a four-part data collection session that consisted of gait evaluation with normal walking, SCKAFO with locked knee joint, SCKAFO without initial flexion (IF) mode, and SCKAFO with IF mode. Results Walking with any of the control knee-ankle-foot orthoses (KAFOs) produced a significant reduction in walking speed compared with normal walking. There was no significant difference in walking speed between the SCKAFO with and without IF. There was significantly higher knee flexion in stance phase when walking with the SCKAFO with IF compared with the other types of KAFO, but there was no significant difference between normal walking and SCKAFO with IF. In wearing SCKAFO with IF, the mean of the hip flexion was not significantly altered compared with normal walking. Hip abduction was also significantly reduced during walking with stance control (SC) mode compared to KAFO with locked knee joint. Conclusion Knee-ankle-foot orthosis with new powered knee joint has benefits over existing assistive KAFOs with locked and SC knee joints. Copyright © 2017 by the American Academy of Orthotists and Prosthetists.
Computers in Biology and Medicine (00104825) 81pp. 159-166
Background Implant loosening may occur after dental implant placement as a result of the mechanical conditions created around the implant. In this research, the effect of bone drilling conditions on the magnitude of stress created in newly-formed bone around the implant, after placement, was investigated using FEA analysis. Method The simulations performed in this study were based on the three-dimensional (3D) shape of the created cavities, extracted from the drilled cortical bone of the jaws. With this aim, a dental implant model was placed in the jaw and a shell of the 3D bone cavity remained as a newly-formed cortical bone after implant placement. Then, a load was exerted on the implant model and the value of stress created on the newly-formed bone was obtained. Overall, eight combined models were used in all the eight drilling and loading simulations. The examined variables were rotational speed of drill bit, its feed rate and head angle. Also, an animal test was performed to investigate the accuracy of the simulation results. Results The results of this study showed that the amount of principal stress was the least (16.7 MPa) for a newly-formed cortical bone whose cavity was created under drilling condition at the same head angle and feed rate of the drill bit with a rotational speed of 400 rpm. The same results were obtained for the head angle and feed rate of a drill bit of 70° and 1.5 mm/s, respectively. Conclusions Drilling conditions have effect on the stress created in a newly-formed cortical bone after dental implant loading. © 2017 Elsevier Ltd
Medical Hypotheses (03069877) 101pp. 37-43
Diabetes and its associated complications are realized as one of the most challenging medical conditions threatening more than 29 million people only in the USA. The forecasts suggest a suffering of more than half a billion worldwide by 2030. Amid all diabetic complications, diabetic foot ulcer (DFU) has attracted much scientific investigations to lead to a better management of this disease. In this paper, a system thinking methodology is adopted to investigate the dynamic nature of the ulceration. The causal loop diagram as a tool is utilized to illustrate the well-researched relations and interrelations between causes of the DFU. The result of clustering causality evaluation suggests a vicious loop that relates external trauma to callus. Consequently a hypothesis is presented which localizes development of foot ulceration considering distribution of normal and shear stress. It specifies that normal and tangential forces, as the main representatives of external trauma, play the most important role in foot ulceration. The evaluation of this hypothesis suggests the significance of the information related to both normal and shear stress for managing DFU. The results also discusses how these two react on different locations on foot such as metatarsal head, heel and hallux. The findings of this study can facilitate tackling the complexity of DFU problem and looking for constructive mitigation measures. Moreover they lead to developing a more promising methodology for managing DFU including better prognosis, designing prosthesis and insoles for DFU and patient caring recommendations. © 2017 Elsevier Ltd
Journal of Mechanics in Medicine and Biology (17936810) 16(3)
The dynamic study of frog's swimming style contributes to the modeling of the nature-inspired robots. To study the torque matrix produced in the joints during continuous modeling, the dynamic model of the Xenopus laevis swimming is reproduced in the coronal plane. The necessary kinematic data for the modeling is extracted from the frog movement graphs and diagrams during swimming. In the dynamic model, legs are considered as a group of rigid links. In order to verify this method, the generated forward force in half a cycle is studied. Unlike the previous studies, the role of geometry, dimensions and mechanical properties of the legs' fundamental links in generating thrust force is modeled in this study, leading to finding the most proper form for this mechanism design. © 2016 World Scientific Publishing Company.
Polish Annals of Medicine (12308013) 23(2)pp. 113-117
Introduction The focus of farm tractor operator is on forward and reverse hydraulic arm's movements in addition to leg-pushing on brake and clutch pedals. Performing all these, with respect to the machine model and operator's position, determines the posture and the loading pattern of the operator's body. Aim The objective here has been the assessment of the pedal control to improve the operator's functionality. Material and methods In this study, 1500 operators were subject to close interviews by the researcher for 3 years in Isfahan Province. Operators with different anthropometries were involved by sitting on MF285, U650, JD3140 and JD950 combiner seats. The operator's knees were photographed in: free (no force enforcement), ready (beginning of force enforcement) and active (force enforcing) conditions. The thigh and leg angle at the knee joint was measured and the exerted force on the leg during leg-pushing was calculated too. Results and discussion Analysis of the obtained data indicated that the MF285 tractor clutch exerted less maximum force on the knee due to the clutch mechanism. The JD3140 clutch needed more maximum force in relation to MF285. The least maximum force was exerted on the brake pedal of JD3140. Under operating conditions, the widest knee extension angle in leg-pushing was of the U650 and JD3140 tractors. Conclusions The U650 and JD3140 model tractors under 'ready' and 'active' conditions need less leg-pushing force. This force exertion from the knee occurs at the widest extension angle. These two models have higher ergonomic level with the least possible disturbance in the knee joint. © 2016 Warmińsko-Mazurska Izba Lekarska w Olsztynie.
British Journal of Oral and Maxillofacial Surgery (15321940) 54(4)pp. 400-404
The main factors that cause an increase in the temperature of the jaw during drilling when implanting teeth are the geometric measurements of the surgical drill, its rotational speed, and its feed rate (cutting speed). Using finite element modelling we analysed the effect of the three variables - the angle of the head of the drill bit, the rotational speed, and the feed rate - on the increase in the temperature of the bone at the point of the drill. This showed that drilling with the angle of the head of the drill bit at 70° generates a lower temperature than when it is at 90° or 118°. The same is true when the drill bit is set at 200 rotations/minute (rpm) compared with 400,800, or 1200 rpm. When the feed rate of the drill bit is 120 mm/minute it generates less heat than when it is at 90 or 60 mm/minute. An increase in temperature during drilling of the jaw has a direct relation with the rotational speed of the drill bit, and a reverse relation to its feed rate. The sharper the drill bit, the lower the temperature during drilling. © 2015 The British Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.
Tehran University Medical Journal (17357322) 74(8)pp. 597-600
Background: Cooling is one of the main processes in bone temperature decrement, while drilling. this experiment was conducted for examination of alcohol effect as cooler in prevention of thermal necrosis. Methods: Bovine femur bone was considered as specimen and inclusions criteria for this study were: femur bone, cortical area and without bone periosteum. Drilling process was conducted by two types of k-wire-Trocar and Diamond, three speeds and three feed rates and in the time of march, 2016 in the place of university of Isfahan, Iran. Two type of thermometer-K-thermocouple and infrared thermometer- were used for temperature measurement, and all data were logged by data logger. Drilling processes were conducted by milling machine with ability of table movement for feed rate parameter. Method of alcohol usage in cooling was in form of conducting alcoholic gauze with k-wire while rotating. Results: Totally in the cases of trocar and diamond wires, while were cooled by alcohol, the risk of bone necrosis decreased about 44.44% and 66.66%. All temperature data were logged by changing parameters. maximum temperature, 94.5 °C, belonged to trocar wire in a non-cooling condition and after usage of cooler it decreased to 75 °C. In the usage of diamond wires, the maximum temperature was recorded 71 °C and the temperature while using alcohol was 51 °C. Diamond wire had better result in both conditions of cooling and no cooling, and this is related to geometric differences between two types of wires. Conclusion: Due to obtained data from examination, utilization alcohol can have an important influence on final bone temperature decreasing. The way of using alcohol was in the style of attrition soaked gauze onto wire while insertion. © 2016, Tehran University of Medical Sciences. All rights reserved.
International Journal of Robotics and Automation (19257090) 31(1)pp. 39-44
In this paper, an analytical approach is presented to compare two important determinants in different stiffness adjustment mechanisms (SAMs); level of accessibility to the energy storage and force-stiffness interaction. These two determinants can actually clarify fitness of variable stiffness actuators (VSAs) for different applications based on their SAMs. Different SAMs have been categorized into antagonistic and series groups. Then antagonistic group is subdivided into three different classes while the series group splits into four classes. In addition, four different springs are considered in analyzing different classes. The obtained results can present a guideline to design a SAM and nonlinearity of the spring in order to enhance the level of accessibility to the energy storage in a SAM.
Journal of Mechanics in Medicine and Biology (17936810) 15(4)
Transfemoral amputation (TFA) results in reduced sensation, altered body image and loss of function. Energy expenditure is known to be significantly higher in individuals with TFA compared with their healthy counterparts. Kinetic and kinematics characteristics of individuals with TFA have been evaluated; however, stability during quiet standing has not been examined. This study evaluated stability, gait performance and energy consumption in individuals with TFA during standing and walking. A total of subjects (5 healthy and 5 with TFA) participated in this study. The motion of lower limb joints and the force applied on the leg were evaluated using a motion analysis system, Qualysis. Stability during standing was examined using a force plate and energy consumption during walking was evaluated based on physiological cost index (PCI). Group comparisons were made using the independent t-test. There was no significant difference in stability between subjects with TFA and normal subjects during standing. However, walking speed in subjects with TFA decreased significantly compared to normal subjects (p = 0.014). PCI of subjects with TFA was 0.525 ± 0.13 compared to 0.298 ± 0.059 beats/m in normal subjects (p < 0.05). It seems that stability in subjects with TFA was similar to their healthy counterparts. However, energy consumption was higher in the TFA group than in normal subjects, which may be due to slow walking speed. Clinicians are to be aware of these findings as they may be useful for effective management of the patients with TFA. © 2015 World Scientific Publishing Company.
Ghassemi a., ,
Mossayebi a.r., ,
Jamshidi, N. ,
Naemi r., ,
Karimi, M.T. Australasian Physical and Engineering Sciences in Medicine (18795447) 38(1)pp. 63-70
Diabetes is one of the metabolic diseases. Uncontrolled diabetes can lead to diabetic foot ulcers and if it was not treated would lead to amputation. Foot ulcers can be prevented by using suitable insoles which are made of appropriate material and geometrically designed by constituent layers. In this study, single-layer and three-layer insoles have been compared during static and dynamic loading. The selected materials were silicone gel (SG), plastazote foam (PLZ), polyfoam (PF) and ethyl vinyl acetate foam (EVA). Four single-layer and 18 combinations of three-layer insoles were selected. Materials behaviors were determined by using a uniaxial pressure test. The description of stress and strain is obtained by using the model of three dimensional nonlinear Finite Element Method (FEM). Then samples were tested by using commercially available plantar pressure measurement system. The FEM results showed that the SG and PLZ insoles are more appropriate compared to single-layer insoles. The combinations of PLZ, SG and EVA (from top to bottom) are recognized as the best between three-layer insoles. Also the best three-layer insole is more effective in promoting a favourable stress and strain distribution than single-layer insoles, especially in dynamic mode. According to simulation results, three-layer insole decreases stress concentration by 9 %. Also experimental tests showed that using three-layer insole decreases plantar pressure by 63 % compared to barefoot condition bare foot. © 2014, Australasian College of Physical Scientists and Engineers in Medicine.
Karimi, M.T. ,
Jamshidi, N. ,
Bahreinizad, H. ,
Bani, M.S. ,
Omar, A.H.H. Work (18759270) 49(4)pp. 663-668
BACKGROUND: Stability during standing is achieved by a complex process which involves the performance of various systems. Using a force plate for analysing the stability for a period of one minute has been reported exclusively by many investigators. Most of people stand for a long period of time when chatting with somebody, doing a job and when waiting in a queue. However nobody has analysed the stability during quiet standing for a prolonged standing (5 minutes). OBJECTIVE: The main aim of this research study was to analyse the performance of the subjects regarding stability for a period of 5 minutes. METHOD: A group of 40 normal subjects from the staff and students of Rehabilitation Faculty of Isfahan University of Medical Sciences were recruited in this research project. They were asked to stand on the force plate (Kistler) for a period of 5 minutes. They were instructed to look straight ahead and with their head erect and their arms at their sides in a comfortable position. The excursions of the COP sway in both planes were measured for all 20 seconds periods of data collection. RESULTS: The results of this research study showed that stability analysing based on the sway of the COP, while the test was collected for one minute, is not recommended. There is a significant difference between the excursions of the COP during the first to fifth minutes. The stability of the subject was optimum in the third and fourth minutes of standing. CONCLUSION: Using the COP sway, based on the first minute of standing, is neither a good representative of the more stable position nor the unstable position. It is recommended to discuss the stability of subjects based on their ability to return from an unstable position to a more stable position. © 2014 -IOS Press and the authors.
Spinal Cord Injury is one of the most important issues of medical society in the world. Problems that the disabled encounter after the accident are significant, namely pressure sores, bone mineral density loss, and disorders in circulation system. The proposed design is a new standing wheelchair that helps the disabled overcome these problems. Affordability and manufacturing problems still exist. Finite element method analysis to find the proper material has been done. The structure is analyzed to obtain the data. The human body was segmented into 11 parts. The result are obtained using ANSYS structural analysis. Results revealed that Poly vinyl chloride can be used instead of stainless steel or aluminum alloy. This concept can change the future of wheelchair production. The mass production will definitely affect the price and the market. © 2014 IEEE.
Nowadays, primary disc degeneration and herniation are treated with total disc replacement. Arthroplasty of degenerated intervertebral disc is alternative to arthrodesis. A successful total disc arthroplasty requires estimating biomechanical behaviors of lumbar section after disc replacement. To achieve an acceptable range of motion for lumbar section, optimum design of intervertebral disc had to be considered. 3D model of an L3-L4 section, based on CT images, was developed using MIMICS software, then the model analyzed by ABAQUS software. In order to show effectiveness of SB ChariteIII behavior, other two model's considering disc fusion and lumbar with intact disc were created. Two disc implants were modelled and assembled with the vertebral segment to simulate disc arthroplasty. Another model with an intact disc was also analyzed for comparison. In this study, design of SB Charitelll with polyethylene core has been used and mechanical behavior of a lumbar vertebral was analyzed. Effects of clinically approved disc implant investigated in comparison to the Intervertébral cage one. © 2014 IEEE.
Biomedical Engineering - Applications, Basis and Communications (10162372) 25(2)
Background: The purpose of this case series was to quantify gait to study muscular dystrophy. In this research, the quantitative differences between normal and waddling gaits were assessed by force plate analysis. Methods: Nineteen myopathy patients and 20 normal subjects serving as the control group participated in this research. In this study, quantitative analyses of gait have been used to investigate the differences in mobility between normal subjects and myopathy patients. Patient data were collected from Iranian Muscular Dystrophy Association members, and normal data were extracted from students of Azad University. All of the gait tests were performed using a Kistler force platform. Participants walked at a self-selected speed, barefoot, independently, and without assistive devices. Results: Our findings indicate that there were no significant differences between the patients and the control group in the anterior-posterior components of the ground reaction forces; however, there were considerable differences in the force components between the groups in the medial-lateral and vertical directions of the ground reaction force. In addition, there were significant differences in the time parameters between the groups along the vertical and medial-lateral directions. © 2013 National Taiwan University.
Jamshidi, N. ,
Sadeghi, M. ,
Farzad, A. ,
Shahraki, O.D. ,
Jamshidi, M. ,
Goudarzi, R. Lecture Notes in Engineering and Computer Science (20780958) 2196pp. 1119-1122
In this paper, a new method for biomedical energy harvesting system equipped in footwear has been proposed, which scavenges power from human gait motion, especially from the hell strike, by means of a power transmission system and a special generator. Once the electricity is generated, the equipped shoe can use the electrical power for rehabilitation purpose such as thermal and cold therapy. Two effective, automatically controlled heating and cooling instruments embedded in the shoe's sole maintain proper temperature and humidity within the normal or user selected range. In addition an alternative cooling system which is less expensive but effective has been proposed. Another useful system is obstacle detecting system for helping people with low-level vision. Few useful accessories including alarm system, distance estimation system have been discussed. Finally the experimental results confirmed the effectiveness of our proposed method.
Australasian Physical and Engineering Sciences in Medicine (18795447) 35(2)pp. 187-191
The aim of this study was examining the effect of human factors such as plantar friction, contact period time, and impulse on shoe-sole trituration of drop foot patients. Twenty-five patients with drop foot and twenty normal subjects were recruited in the study. The force plate and its related software's recorded human factor (coefficient of friction, ground reaction force, time of stance phase) as time dependent parameters. Dynamic coefficient of friction patterns were categorized based on their magnitude versus time when the longitudinal axis of the sole was plotted as the Y-Axis and the transverse axis of the sole as X-Axis during stance phase. The result of this research indicated that the average coefficient of friction among drop foot patients is 77.53 % (p value<0.05) lower than the normal subjects. Also the time of stance phase among drop foot patients is 7.56 % (p value<0.05) greater than normal subjects. There is no difference in the peaks, of vertical ground reaction force between normal and control group. The findings of this research revealed that the time of stance phase has a key role in shoe-sole trituration of patients with drop foot. © Australasian College of Physical Scientists and Engineers in Medicine 2012.
Medical Hypotheses (03069877) 79(3)pp. 334-337
In this research kinematics parameters derived from ground reaction forces were evaluated to limit differential diagnoses and measure the degree of disabilities during walking among neuropathic subjects. 25 neuropathic subjects affected by drop foot and 20 normal subjects were enrolled in the study. Each subject was tested in average 10 ± 2 times for calculating kinetics parameters derived from ground reaction forces. The results revealed that the center of pressure displacement pattern in sole of foot can be a good index for differential diagnoses and measuring the degree of disabilities. This research can extend the clinical applications of ground reaction force plate and introduce suitable criteria to measure the degree of disability among neuropathic patients. © 2012 Elsevier Ltd.
Journal Of Medical Signals And Sensors (22287477) 2(4)pp. 225-230
Measurement of the loads exerted on the limb is a fundamental part of designing of an assistive device, which has been done by using strain gauges or a transducer. Although calculation of loads applied on an orthosis coefficients achieved from calibration is a standard way, most of researchers determined the loads based on available equations. Therefore, the aim of this research is finding the accuracy of this method with respect to calibration. Some strain gauges were attached on the lateral bar of a reciprocal gait orthosis. It was calibrated for axial force and the anteroposterior and mediolateral moments. The outputs of strain gauge were changed to force, and moments based on the coefficients were achieved from calibration using available equations, while 5 normal subjects were walking with the orthosis. There was a significant difference between the force and moments exerted on the orthosis during walking based on the two methods (mostly extension moment and compression force). The results of this research indicated that the output of strain gauge varies based on the methods of calculation. As calibration the gauge is a standard method, it is recommended to calibrate it before use.
Jamshidi, N. ,
Rostami, M. ,
Najarian, S. ,
Menhaj, M.B. ,
Saadatnia, M. ,
Firooz, S. Journal Of Research In Medical Sciences (17357136) 15(1)pp. 33-40
BACKGROUND: This pilot study aimed to assess the differences in center of pressure trajectory in neuropathic patients with steppage gait. Steppage gait has previously been evaluated by several biomechanical methods, but plantar pressure distribution has been much less studied. The purpose of this study was to analyze the changes in center of pressure trajectory using a force plate. METHODS: The steppage gait group was selected from the patients using drop foot brace (25 male) and the control group was selected from Isfahan university students (20 male). They walked at self-selected speed at a mean of ten trials (+2) to collect the center of pressure using a force plate. Center of pressure patterns were categorized into four patterns based on the center of pressure displacement magnitude (spatial features) through time (temporal features) when the longitudinal axis of the insole was plotted as the Y-axis and the transverse axis of the insole as X-axis during stance phase. RESULTS: The horizontal angle measured from center of pressure linear regression was positive in the control group (4.6 ± 2.4) (p < 0.005), but negative in the patient group (-2.3 ± 1.6) (p < 0.005). CONCLUSIONS: The finding of this research measured center of pressure trajectory in steppage gait over time, which is useful for designing better shoe sole and also orthopaedic device and better understanding of stability in patients with drop foot.
Jamshidi, N. ,
Hanife h., ,
Rostami, M. ,
Najarian, S. ,
Menhaj, M.B. ,
Saadatnia, M. ,
Firooz, S. Journal of Medical Engineering and Technology (1464522X) 34(2)pp. 116-123
In this study, based on kinematics data in steppage gait, a finite element model of human gait with ankle-foot orthosis (AFO) has been proposed to optimize the role of AFO through minimizing stress in the patients' sole. The required kinetics data for the model were captured through a force plate and then analysed by 3D-DOCTOR and ANSYS software. In the proposed three-dimensional finite element model the transmitted tension in soft tissue and bones during gait was calculated. By changing the thickness and materials of different layers of sole in AFO the tension variations have been assessed. Unlike previous studies, the effect of orthosis on tension generated in bones and muscles has been dynamically and continuously modelled and the contact between AFO and sole has been considered in this model. By using the optimized sole the stress distribution has been changed by +50.38% in the forefoot, +15% in the midfoot and -37.79% in the hindfoot. The tension reduction in the sole can improve the effect of AFO during abnormal gait. It is possible to design each orthosis sole based on the kinetics data of each patient.
Jamshidi, N. ,
Rostami, M. ,
Najarian, S. ,
Menhaj, M.B. ,
Saadatnia, M. ,
Firooz, S. Journal of Musculoskeletal Research (17936497) 12(1)pp. 45-52
Background: This pilot study aimed to assess quantitative differences between normal and steppage gait by analyzing force plate data. Materials and Methods: We studied 25 subjects with drop foot, who were treated in the orthopedic center for drop foot brace. Twenty healthy students were included as a control group. There were no differences in the age, weight, height, and body mass index between the patients and the controls (p > 0.05). They walked at self-selected speed with a mean of 10 trials (+2) to collect their ground reaction forces data by force plate. Results: There were no significant differences between the groups in antero-posterior component of ground reaction force (p > 0.05). There was significant relationship between the time parameters in vertical and medio-lateral components of ground reaction forces (p > 0.05). We have found that the medio-lateral impulse in the patients group is negative (p > 0.05), which means instability in patients' gait. Conclusion: The result of this research reveals that the analysis of ground reaction force quantitatively describes steppage gait. The average stance time among patients is longer than control group. Further work with a larger database of subjects is required to confirm our findings. © 2009 World Scientific Publishing Company.
Jamshidi, N. ,
Rostami, M. ,
Najarian, S. ,
Menhaj, M.B. ,
Saadatnia, M. ,
Firooz, S. Singapore Medical Journal (00375675) 50(4)pp. 412-417
Introduction: This paper deals with the dynamic modelling of human walking. The main focus of this research was to optimise the function of the orthosis in patients with neuropathic feet, based on the kinematics data from different categories of neuropathic patients. Methods: The patient's body on the sagittal plane was modelled for calculating the torques generated in joints. The kinematics data required for mathematical modelling of the patients were obtained from the films of patients captured by high speed camera, and then the films were analysed through a motion analysis software. An inverse dynamic model was used for estimating the spring coefficient. Results: In our dynamic model, the role of muscles was substituted by adding a spring-damper between the shank and ankle that could compensate for their weakness by designing ankle-foot orthoses based on the kinematics data obtained from the patients. The torque generated in the ankle was varied by changing the spring constant. Therefore, it was possible to decrease the torque generated in muscles which could lead to the design of more comfortable and efficient orthoses. Conclusion: In this research, unlike previous research activities, instead of studying the abnormal gait or modelling the ankle-foot orthosis separately, the function of the ankle-foot orthosis on the abnormal gait has been quantitatively improved through a correction of the torque.
Jamshidi, N. ,
Rostami, M. ,
Najarian, S. ,
Menhaj, M.B. ,
Saadatnia, M. ,
Farzad a.,
The aim of this paper was to present the optimum parameters of an ankle foot Orthosis (AFO) using dashpot-spring modeling. Using kinematic and force data joints moment were determined through the calculations of inverse dynamics. In the proposed dynamic model selected muscles of shank and foot were replaced by spring-damper The generated torque in ankle could be modifided by changing the spring constant. Therefore it was possible to design a more comfortable AFO by modifying the parametes of the dashpot-spring of the model. Therefore, in this paper, the final goal was to help design AFOs which are more suitable to offset the deficiency of the lower limb muscles. © 2008 IEEE.
American Journal of Applied Sciences (discontinued) (15469239) 5(9)pp. 1175-1181
This paper deals with dynamic optimization of biped locomotion. The main focus of this research is motion optimization of double support phase. The optimization problem is dealt by using Pontryagins; Maximum Principal. For motion optimization of double support phase, the closed kinematic chain has been considered to be opened at appropriate joint and the components of ground reaction forces has been applied on the tip of front leg and finally the penalty method has been used to tighten the leg to its prescribed location. The feasible sets of motion are taken into consideration by using inequality constraint to limit the joint motion. Also the components of ground reaction forces on front leg have been introduced as control variables in optimization of double support phase. The proposed technique has the ability to generate optimal free motions without specifying joint trajectories and minimized the performance criterion based on joint actuating torques. The two point boundary value problem has been solved by implementing a shooting method. This technique allows for specifying a few parameters to characterize gait pattern. The optimization process has the ability to generate a motion with a minimum of postural and kinematics data. Unlike previous research which used computational intelligent techniques for biped gait optimization, this study focuses on development of purely dynamic synthesis of biped motion during the double support phase. © 2008 Science Publications.
American Journal of Applied Sciences (discontinued) (15469239) 5(12)pp. 1670-1675
In this research, an athlete's body on sagittal plane in tension phase of snatch weightlifting has been modeled in two dimensions for calculating the generated torques in joints. The error back propagation multi-layer perceptrons has been used for modeling the torque through changing the angular velocity, angular acceleration and absolute angle of each segment. Finally, the torque in joints has been minimized by particle swarm optimization technique and the power of athlete has been maximized. The method of weightlifting has been captured by high speed camera and the films have been analyzed through motion analysis software. Consequently, the required kinematic data for mathematical model of weightlifter has been produced. Unlike previous research reports, the technique of weightlifting has been modified with the aid of artificial neural network modeling to enhance athlete's power, instead of optimizing the effect of body parameters and sport facilities. In addition, this study focuses on computational intelligent techniques for optimization instead of classical methods. © 2008 Science Publications.
In this paper the weightlifters snatch optimization will be studied. The biomechanical model is used for two-dimensional modeling on sagittal plan. It is estimated by an error back propagation network, in a way that inputs of this network are kinematics data such as absolute angular velocity, relative angles of joints, of different body segments and output is created torque at the joints. Finally the neural network model has been optimized for minimizing the created torque at the joints.
