Search for: implants--surgical
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    Aseptic loosening of femoral components - Materials engineering and design considerations

    , Article Materials and Design ; Volume 44 , February , 2013 , Pages 155-163 ; 02641275 (ISSN) Bahraminasab, M ; Sahari, B. B ; Edwards, K. L ; Farahmand, F ; Arumugam, M ; Sharif University of Technology
    Aseptic loosening is one of the main reasons for the revision of a total knee replacement (TKR). The design of the key component of a TKR, the femoral component, is particularly problematic because its failure can be the result of different causes. This makes the development of new biomaterials for use in the femoral component a challenging task. This paper focuses on the engineering design aspects in order to understand the limitationsof current materials and design deficiencies. The paper describes the introduction of a new biomaterial for a femoral component and justifies the recommendation to use multi-functional materials as a possible solution to aseptic loosening. The potential... 

    Aseptic loosening of femoral components - A review of current and future trends in materials used

    , Article Materials and Design ; Volume 42 , 2012 , Pages 459-470 ; 02641275 (ISSN) Bahraminasab, M ; Sahari, B. B ; Edwards, K. L ; Farahmand, F ; Arumugam, M ; Hong, T. S ; Sharif University of Technology
    The variety of new biomaterials and different surface treatments being applied to existing materials all intended for total knee replacement (TKR) are self-evident of the demand for longer lasting knee prostheses. Aseptic loosening is one of the main reasons for the revision of TKR components including the femoral component, which has more challenging problems because of the different causes of failure. This paper therefore, focuses on aseptic loosening of femoral components and materials options available. Several current and promising new metallic, ceramic and polymeric biomaterials are discussed to highlight their advantages and their shortcomings. It is concluded that current materials... 

    Novel methodology in design of custom-made hip prosthesis

    , Article Innovative Developments in Design and Manufacturing - Advanced Research in Virtual and Rapid Prototyping, 6 October 2009 through 10 October 2009, Leiria ; 2010 , Pages 117-126 ; 9780415873079 (ISBN) Abbaszadeh, F ; Rahmati, S ; Farahmand, F ; Fatollahzadeh, R ; Sharif University of Technology
    Medical applications of rapid prototyping have an increasing trend, making the future of RP more and more promising. These applications may include design, development, and manufacture of medical devices and instrumentation, as well as implant design, anatomical modeling, surgical planning, surgical implants, and prosthesis fabrication. This paper provides a new methodology for customized hip prosthesis that could provide high accuracy of femoral canal reconstruction via 3D modeling of prosthesis stem, 3D modeling of prosthesis neck, and facilitating the communication between the designer and surgeon. Combining RP technologies and rapid tooling with this novel custom-made hip prosthesis,... 

    Estimation of loads on human lumbar spine: A review of in vivo and computational model studies

    , Article Journal of Biomechanics ; Volume 49, Issue 6 , 2016 , Pages 833-845 ; 00219290 (ISSN) Dreischarf, M ; Shirazi Adl, A ; Arjmand, N ; Rohlmann, A ; Schmidt, H ; Wolff Institut, Julius ; Sharif University of Technology
    Elsevier Ltd 
    Spinal loads are recognized to play a causative role in back disorders and pain. Knowledge of lumbar spinal loads is required in proper management of various spinal disorders, effective risk prevention and assessment in the workplace, sports and rehabilitation, realistic testing of spinal implants as well as adequate loading in in vitro studies. During the last few decades, researchers have used a number of techniques to estimate spinal loads by measuring in vivo changes in the intradiscal pressure, body height, or forces and moments transmitted via instrumented vertebral implants. In parallel, computational models have been employed to estimate muscle forces and spinal loads under various... 

    Phase transformation behavior of porous NiTi alloy fabricated by powder metallurgical method

    , Article Materials Science and Engineering C ; Volume 29, Issue 7 , 2009 , Pages 2203-2207 ; 09284931 (ISSN) Hosseini, S. A ; Sadrnezhaad, S. K ; Ekrami, A ; Sharif University of Technology
    Nickel titanium shape memory alloys (NiTi-SMAs) were successfully produced from elemental Ni/Ti powders by powder metallurgical method and then subjected to age treatment. Microstructure was examined by SEM and XRD and phase transformation temperatures were measured by dilatometric method. The phase transformation temperatures increased with both duration and temperature of the age treatment. The porous product exhibited desirable shape memory effect. © 2009 Elsevier B.V. All rights reserved  

    An open-loop double-carrier simultaneous wireless power and data transfer system

    , Article IEEE Transactions on Circuits and Systems II: Express Briefs ; Volume 66, Issue 5 , 2019 , Pages 823-827 ; 15497747 (ISSN) Najjarzadegan, M ; Hadizadeh Hafshejani, E ; Mirabbasi, S ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2019
    In this brief, an open-loop double-carrier simultaneous wireless power and data transfer system is presented. Although the system is intended for implantable biomedical microsystems, it can also be used for other low-power applications such as Internet of Things (IoT). In the proposed system, uplink data communication (from the implant to the outside of the body) is implemented by switching a capacitor on the implant site. This switching results in changing the resonance frequency between two different frequencies during different periods of time. To keep the power transfer efficiency (PTE) and the power delivered to the load (PDL) almost constant, two external power transmitters, each... 

    Multi-objective design optimization of functionally graded material for the femoral component of a total knee replacement

    , Article Materials and Design ; Vol. 53, Issue. 1 , 2014 , pp. 159-173 ; ISSN: 0895-7177 Bahraminasab, M ; Sahari, B. B ; Edwards, K. L ; Farahmand, F ; Hong, T. S ; Arumugam, M ; Jahan, A ; Sharif University of Technology
    The optimal design of complex systems in engineering requires pursuing rigorous mathematical modeling of the system's behavior as a function of a set of design variables to achieve goal-oriented design. Despite the success of current knee implants, the limited life span remains the main concern of this complex system. The mismatch between the properties of engineered biomaterials and those of biological materials leads to insufficient bonding with bone, stress shielding effects and wear problems (i.e. aseptic loosening). The use of a functionally graded material (FGM) for the femoral component of knee implants is attractive because the properties can be designed to vary in a certain pattern... 

    On the influence of shape and material used for the femoral component pegs in knee prostheses for reducing the problem of aseptic loosening

    , Article Materials and Design ; Vol. 55, issue , March , 2014 , p. 416-428 Bahraminasab, M ; Sahari, B. B ; Edwards, K. L ; Farahmand, F ; Jahan, A ; Hong, T. S ; Arumugam, M ; Sharif University of Technology
    The integration of materials selection and design are essential to the success of new product development, especially when applied to biomedical devices. The knee prosthesis, like any other implant, is a product that still lacks satisfactory design solutions for solving the problem of aseptic loosening. Stress shielding is one of the main causes of aseptic loosening that is intimately related to the overall design of the knee prosthesis. The design of the location pegs in the femoral component of the knee prosthesis is seen to have a critical effect on the stress shielding. In this study, therefore, different combinations of location peg geometries and material designs were assessed using... 

    Material tailoring of the femoral component in a total knee replacement to reduce the problem of aseptic loosening

    , Article Materials and Design ; Volume 52 , 2013 , Pages 441-451 ; 02641275 (ISSN) Bahraminasab, M ; Sahari, B. B ; Edwards, K. L ; Farahmand, F ; Hong, T. S ; Naghibi, H ; Sharif University of Technology
    Elsevier Ltd  2013
    Aseptic loosening of femoral components is a significant problem affecting the life of current total knee replacements. To help reduce the problem of aseptic loosening, a new metal-ceramic poros functionally graded biomaterial (FGBM) has been designed to replace the existing metal alloy material normally used. In order to investigate the effect of using a FGBM on distal femur stresses compared to using standard material in a femoral component, a three-dimensional finite element model of the knee prosthesis has been developed. The results of the modeling and subsequent analysis indicate that by using the new FGBM compared to the existing material in a femoral component, higher levels of... 

    Computational pharmacokinetics of solute penetration into human intervertebral discs-Effects of endplate permeability, solute molecular weight and disc size

    , Article Journal of Biomechanics ; Volume 45, Issue 13 , 2012 , Pages 2195-2202 ; 00219290 (ISSN) Motaghinasab, S ; Shirazi Adl, A ; Urban, J. P. G ; Parnianpour, M ; Sharif University of Technology
    A finite element model is developed to predict the penetration time-history of three different solutes into the human lumbar disc following intravenous injection. Antibiotics are routinely administered intravenously in spinal surgery to prevent disc infection. Successful prophylaxis requires antibiotics to reach adequate inhibitory levels. Here, the transient diffusion of cephazolin is investigated over 10. h post-injection in a human disc model subject to reported concentrations in the blood stream as the prescribed boundary sources. Post-injection variation of cephazolin concentrations in the disc adjacent to supply sources closely followed the decay curve in the blood stream and fell... 

    Sol-gel derived hydroxyapatite coating on TiB 2/TiB/Ti substrate

    , Article Surface Engineering ; Volume 28, Issue 7 , August , 2012 , Pages 526-531 ; 02670844 (ISSN) Esfahani, H ; Dabir, F ; Taheri, M ; Sohrabi, N ; Toroghinejad, M. R ; Sharif University of Technology
    The low erosion resistance of titanium and its alloys has prevented their widespread application as joint implants. In addition, one essential requirement for the implants to bond with the living bone is the formation of a bone-like apatite on their surfaces in the host body. To enhance the erosion resistance of the surface, a diffused layer of TiB2 was formed at 1000uC on the commercial pure titanium. Hydroxyapatite was then coated on the boronised titanium by means of dip coating in a sol-gel solution. In order to confirm the biocompatibility of the specimens, they were soaked in a simulated body fluid for several days. The surface morphology of the specimens after exposure was studied by... 

    A study of the electrophoretic deposition of bioactive glass-chitosan composite coating

    , Article Ceramics International ; Volume 38, Issue 1 , January , 2012 , Pages 471-476 ; 02728842 (ISSN) Mehdipour, M ; Afshar, A ; Sharif University of Technology
    Bioactive glass is coated on implant's surface to improve corrosion resistance and osseointegration, when placed in the body. Bioactive glass particles were synthesized through a sol-gel process and deposited along with chitosan to form a composite coating on a stainless steel substrate using electrophoretic deposition technique. Stable suspensions of chitosan-bioactive glass were prepared using bioactive glass particles (<1 μm) and 0.5 g/l chitosan solution. The influence of ethanol-water ratio on deposition yield was investigated. For all process conditions, best results were achieved with suspension of 30 vol% water in ethanol-water containing 2 g/l bioactive glass. FTIR studies showed... 

    The nonlinear finite element analysis of a novel dental implant with an interposed internal layer imitating periodontal ligament's function

    , Article ASME 2011 International Mechanical Engineering Congress and Exposition, IMECE 2011, 11 November 2011 through 17 November 2011 ; Volume 2 , November , 2011 , Pages 543-548 ; 9780791854884 (ISBN) Ahmadian, M. T ; Ghanati, G ; Firoozbakhsh, K ; Ghanati, P ; Sharif University of Technology
    Osseointegrated dental implants are deficient in natural periodontal ligaments. It may therefore, disrupts the natural function of implant and leads to excessive stress and strain in jaw bone. Our new proposed implant has the nonlinear internal component which imitates periodontal ligaments function. A nonlinear finite element analysis developed to investigate the efficiency of utilizing this nonlinear internal layer for three conditions of bone implant interface conditions under vertical and horizontal loading conditions. Our results so far indicate that the use of a class of material exhibiting incompressible hyperelastic behaviour as a internal layer can reduce the peak stress deduced... 

    Electrophoretic deposition of nano-zirconia coating on AZ91D magnesium alloy for bio-corrosion control purposes

    , Article Surface and Coatings Technology ; Volume 311 , 2017 , Pages 182-190 ; 02578972 (ISSN) Amiri, H ; Mohammadi, I ; Afshar, A ; Sharif University of Technology
    Elsevier B.V  2017
    Magnesium alloys are considered as potential biodegradable biomaterials in hard tissue implants. However, the fast degradation rate of these alloys in the biological environment causes failure of the implant just prior to the desirable time. In the present work, in order to decrease and curb the bio-corrosion rate of AZ91D Magnesium alloy, zirconia, which is classified as a biocompatible ceramic, was coated on the alloy surface through electrophoretic deposition (EPD) technique. The effects of alterations in the EPD parameters such as current density, duration time and ZrO2 particles concentration on coating properties including thickness, morphology and adhesion were then characterized.... 

    Enhanced chondrogenic differentiation of human bone marrow mesenchymal stem cells on PCL/PLGA electrospun with different alignments and compositions

    , Article International Journal of Polymeric Materials and Polymeric Biomaterials ; Volume 67, Issue 1 , 2018 , Pages 50-60 ; 00914037 (ISSN) Zamanlui, S ; Mahmoudifard, M ; Soleimani, M ; Bakhshandeh, B ; Vasei, M ; Faghihi, S ; Sharif University of Technology
    Taylor and Francis Inc  2018
    The simultaneous effect of electrospun scaffold alignment and polymer composition on chondrogenic differentiation of human bone marrow mesenchymal stem cells (hBMMSC) is investigated. Aligned and randomly oriented polycaprolactone/poly(lactic-co-glycolic acid) (PLGA) hybrid electrospun scaffolds with two different ratios are fabricated by electrospinning. It is found that aligned nanofibrous scaffolds support higher chondrogenic differentiation of hBMMSCs compared to random ones. The aligned scaffolds show a higher expression level of chondrogenic markers such as type II collagen and aggrecan. It is concluded that the aligned nanofibrous scaffold with higher PLGA ratio could significantly... 

    Explicit finite element modeling of wear within the patellofemoral joint in total knee replacement

    , Article 26th National and 4th International Iranian Conference on Biomedical Engineering, ICBME 2019, 27 November 2019 through 28 November 2019 ; 2019 , Pages 208-212 ; 9781728156637 (ISBN) Bahadoran, M ; Dorri Nokoorani, Y ; Barati, K ; Farahmand, F ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2019
    Total knee replacement (TKR) surgery is one of the most successful and cost-effective procedures for treating knee injuries performed in orthopedics. However, the knee replacement revision surgery will probably be required after some years. Wear at the contact area between femoral metal component and the polyethylene inserts in TKR is recognized as one of the foremost causes of prosthesis failure and necessity of revision surgery. In the present study, focusing on the patellofemoral joint (PFJ), the wear at the contact area between the patellar and femoral components has been simulated employing the explicit finite element modeling. In this regard, common types of patellar component surface... 

    Low power receiver with merged N-path LNA and mixer for MICS applications

    , Article AEU - International Journal of Electronics and Communications ; Volume 117 , 2020 Beigi, A ; Safarian, A ; Sharif University of Technology
    Elsevier GmbH  2020
    In this paper, a low power receiver for medical implant communication service (MICS) is presented. Low power design is vital in the MICS applications since the implanted chip has to work for a long time without the need to change its battery. As a result, a merged N-path low noise amplifier (LNA) and mixer block is proposed. In this structure, the LNA and down-conversion mixer share a transconductance to lower the overall power consumption. An N-path feedback is utilized around the shared transconductance not only to improve the LNA selectivity and relax the linearity requirements but also to downconvert the radio frequency (RF) component and create the intermediate frequency (IF) signal. In... 

    Bioinspired multifunctional TiO2 hierarchical micro/nanostructures with tunable improved bone cell growth and inhibited bacteria adhesion

    , Article Ceramics International ; Volume 46, Issue 7 , 2020 , Pages 9669-9679 Rahnamaee, S. Y ; Bagheri, R ; Vossoughi, M ; Ahmadi Seyedkhani, S ; Samadikuchaksaraei, A ; Sharif University of Technology
    Elsevier Ltd  2020
    Two main origins of failure for hard tissue replacements are structural loosening and prosthetic implant infections (PIIs). Bioinspired multifunctional TiO2 hierarchical micro/nanostructures of conical-shaped TiO2 (CTO), regular TiO2 nanotubes (RTO) and irregular TiO2 nanotubes (ITO) with tunable improved cell growth and inhibited bacteria adhesion were synthesized. CTO and ITO samples indicated superhydrophilicity with contact angles of less than 5°. The MTT assay demonstrated excellent biological performance for RTO and CTO sample with 98.1% and 103.1% of cell viability, respectively. The bridging force for osteoblast cell attachment onto the synthesized porous coatings was presented as a... 

    A meta-model analysis of a finite element simulation for defining poroelastic properties of intervertebral discs

    , Article Proceedings of the Institution of Mechanical Engineers, Part H: Journal of Engineering in Medicine ; Volume 227, Issue 6 , 2013 , Pages 672-682 ; 09544119 (ISSN) Nikkhoo, M ; Hsu, Y. C ; Haghpanahi, M ; Parnianpour, M ; Wang, J. L ; Sharif University of Technology
    Finite element analysis is an effective tool to evaluate the material properties of living tissue. For an interactive optimization procedure, the finite element analysis usually needs many simulations to reach a reasonable solution. The metamodel analysis of finite element simulation can be used to reduce the computation of a structure with complex geometry or a material with composite constitutive equations. The intervertebral disc is a complex, heterogeneous, and hydrated porous structure. A poroelastic finite element model can be used to observe the fluid transferring, pressure deviation, and other properties within the disc. Defining reasonable poroelastic material properties of the... 

    Biomechanical response of intact, degenerated and repaired intervertebral discs under impact loading – Ex-vivo and In-Silico investigation

    , Article Journal of Biomechanics ; Volume 70 , March , 2018 , Pages 26-32 ; 00219290 (ISSN) Nikkhoo, M ; Wang, J. L ; Parnianpour, M ; El-Rich, M ; Khalaf, K ; Sharif University of Technology
    Elsevier Ltd  2018
    Understanding the effect of impact loading on the mechanical response of the intervertebral disc (IVD) is valuable for investigating injury mechanisms and devising effective therapeutic modalities. This study used 24 porcine thoracic motion segments to characterize the mechanical response of intact (N = 8), degenerated (Trypsin-denatured, N = 8), and repaired (Genepin-treated, N = 8) IVDs subject to impact loading. A meta-model analysis of poroelastic finite element simulations was used in combination with ex-vivo creep and impact tests to extract the material properties. Forward analyses using updated specimen-specific FE models were performed to evaluate the effect of impact duration. The...