Browsing by Author "Gok K."

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    Biomechanical effects of three different configurations in Salter Harris type 3 distal femoral epiphyseal fractures
    (Springer Verlag, 2017) Gok K.; Inal S.; Gok A.; Pinar A.M.
    In this study, the biomechanical effects of three different configurations (K-wire, stainless steel screws, and titanium screws), which are used for stabilizing Salter–Harris (SH) type 3 epiphyseal fracture of distal femur after reduction process, on the epiphyseal plate and fracture line have been investigated under axial, rotational, and bending forces to determine the most advantageous configuration. Three different configurations have been modeled using SolidWorks, and computer-aided numerical analyses were performed by finite-element analysis software. For each configuration, mesh process, boundary conditions, and material model have been applied in finite-element analysis software. In addition, von Mises stress values on growth of epiphyseal plate and K-wire have been calculated. According to the results obtained, it has been found particularly advantageous to use the fixation shape of configuration with screw. In addition, the fixation shape of K-wire configuration was found to be disadvantageous in the SH type 3 epiphyseal fractures. © 2016, The Brazilian Society of Mechanical Sciences and Engineering.
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    NUMERICAL ANALYSIS of TEMPERATURE, SCREWING MOMENT and THRUST FORCE USING FINITE ELEMENT METHOD in BONE SCREWING PROCESS
    (World Scientific Publishing Co. Pte Ltd, 2017) Erdem M.; Gok K.; Gokce B.; Gok A.
    In this study, the bone screwing process carried out with M3.5 cortex screw for stabilization after reduction of femur shaft fracture was investigated both experimentally and numerically. The numerical analyses were performed based on the finite element method using Deform-3D software. The friction, material model, the loading and boundary conditions were exactly identified for finite element analyses. An analytic model and software were developed, which calculate the process parameters such as screwing power and thrust power, heat transfer coefficients in order to determine the temperature distributions occurring in the screw and bone material (sawbones) during screwing process. As a result, the screwing moment and thrust force values decrease with increase of spindle speed. On the contrary, temperature values of screw and sawbones increase with increase of spindle speed. A good consistency between the results obtained from both experimental and numerical simulations was found during the bone screwing process. © 2017 World Scientific Publishing Company.
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    Response concerning ‘Letter to editor’ by Ni et al. (2017), Arch Orthop Trauma Surg. DOI 10.1007/s00402-017-2710-2
    (Springer Verlag, 2017) Gok K.; Inal S.; Gok A.; Gulbandilar E.
    [No abstract available]
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    Comparison of parallel or convergent proximal schanz screw placement of pertrochanteric fixator in intertrochanteric fracture model
    (Copernicus GmbH, 2017) Gok A.; Inal S.; Taspinar F.; Gulbandilar E.; Gok K.
    Intertrochanteric femoral fractures are serious traumas among elderly patients. In these patients, external fixator is a preferable method for the fixation of fractures. Therefore, this study was planned to compare the parallel and convergent proximal schanz screw placement of pertrochanteric fixator in the intertrochanteric femoral fractures with respect to biomechanical forces that stabilize the fracture line and to present their clinical importance. A commercial finite element based program, AnsysWorkbench was used to investigate the biomechanical parameters of the femoral intertrochanteric fractures and different placement of implants. The von Mises stress, von Mises strain and shear stress on the proximal and distal surface of the fracture line were lower in the convergent pertrochanteric fixator. Proximal schanz screws in convergent configuration pertrochanteric fixator had greater stress and strain values than proximal schanz screws in parallel configuration pertrochanteric fixator. The distance between the proximal schanz screws on the fracture line was measured as 12 mm in convergent configuration pertrochanteric fixator, and as 3.5 mm in parallel configuration pertrochanteric fixator. The angle between the proximal schanz screws in the convergent configuration was measured as 12.88°. The effect of convergent and parallel configuration pertrochanteric fixators on axial loading demonstrated that convergent configuration pertrochanteric fixator was safer in this respect. © 2017 Author(s).
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    Comparison of effects of different screw materials in the triangle fixation of femoral neck fractures
    (Springer New York LLC, 2017) Gok K.; Inal S.; Gok A.; Gulbandilar E.
    Abstract: In this study, biomechanical behaviors of three different screw materials (stainless steel, titanium and cobalt–chromium) have analyzed to fix with triangle fixation under axial loading in femoral neck fracture and which material is best has been investigated. Point cloud obtained after scanning the human femoral model with the three dimensional (3D) scanner and this point cloud has been converted to 3D femoral model by Geomagic Studio software. Femoral neck fracture was modeled by SolidWorks software for only triangle configuration and computer-aided numerical analyses of three different materials have been carried out by AnsysWorkbench finite element analysis (FEA) software. The loading, boundary conditions and material properties have prepared for FEA and Von-Misses stress values on upper and lower proximity of the femur and screws have been calculated. At the end of numerical analyses, the best advantageous screw material has calculated as titanium because it creates minimum stress at the upper and lower proximity of the fracture line. Graphical Abstract: [InlineMediaObject not available: see fulltext.] © 2017, Springer Science+Business Media New York.
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    Should we really compress the fracture line in the treatment of Salter–Harris type 4 distal femoral fractures? A biomechanical study
    (Springer Verlag, 2018) Inal S.; Gok K.; Gok A.; Uzumcugil A.O.; Kuyubasi S.N.
    In this study, the indirect effect on physeal plate during interfragmentary compression of a Salter–Harris (SH) type 4 distal femoral fracture has been investigated. Three Dimensional (3D) model of a single configuration has been performed via SolidWorks. ANSYS Workbench software was used for numerical analyses. All boundary conditions have been defined in finite element analysis software. Since it is premature to state that compression created an additional stress load on the physeal plate in vivo, according to our results, it has been found that lateromedial compression in SH type 4 fracture of the distal femur caused an additional stress load on the physeal plate ex vivo. It is believed that screws need to be fixed without compression to avoid an additional iatrogenic physeal injury. © 2018, The Brazilian Society of Mechanical Sciences and Engineering.
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    Biomechanical performance using finite element analysis of different screw materials in the parallel screw fixation of Salter–Harris Type 4 fractures
    (Springer Verlag, 2019) Gok K.; Inal S.; Urtekin L.; Gok A.
    The biomechanical performance of stainless steel, titanium alloy, cobalt–chromium and NiTi alloy has been compared to fix with parallel fixation in Salter–Harris Type 4 fractures. The best material has been determined under the axial load. 3D model of the parallel fixation has been performed via SolidWorks. Ansys Workbench software was used for numerical analyses. All boundary conditions have defined in finite element analysis (FEA) software. The boundary conditions such as the loading, contact, friction and material model have been determined for FEA. The stress values occurring in the epiphyseal plate of the femur, upper screw and lower screw have been calculated based on von-Mises criteria. At the end of numerical analyses, we have the opinion that, in practice, use of Ti screws in Salter–Harris Type 4 distal femoral fractures will be advantageous. © 2019, The Brazilian Society of Mechanical Sciences and Engineering.
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    Comparison of biomechanical effects of different configurations of kirschner wires on the epiphyseal plate and stability in a salter-harris type 2 distal femoral fracture model
    (American Podiatric Medical Association, 2019) Inal S.; Gok K.; Gok A.; Pinar A.M.; Inal C.
    Background: We sought to investigate the different configurations of Kirschner wires used in distal femur Salter-Harris (SH) type 2 epiphyseal fracture for stabilization after reduction under axial, rotational, and bending forces and to define the biomechanical effects on the epiphyseal plate and the fracture line and decide which was more advantageous. Methods: The SH type 2 fracture was modeled using design software for four different configurations: Cross, cross-parallel, parallel medial, and parallel lateral with two Kirschner wires, and computer-aided numerical analyses of the different configurations after reduction were performed using the finite element method. For each configuration, the mesh process, loading condition (axial, bending, and rotational), boundary conditions, and material models were applied in finite element software, and growth cartilage and von Mises stress values occurring around the Kirschner wire groove were calculated. Results: In growth cartilage, the stresses were highest in the parallel lateral configuration and lowest in the cross configuration. In Kirschner wires, the stresses were highest in the cross configuration and lowest in the cross-parallel and parallel lateral configurations. In the groove between the growth cartilage and the Kirschner wire interface, the stresses were highest in the parallel lateral configuration and lowest in the cross configuration. Conclusions: The results showed that the cross configuration is advantageous in fixation. In addition, in the SH type 2 epiphyseal fracture, we believe that the fixation shape should not be applied in the lateral configuration. © 2019, American Podiatric Medical Association. All rights reserved.
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    Computer Aided Finite Element Simulation of the Developed Driller System for Bone Drilling Process in Orthopedic Surgery
    (World Scientific Publishing Co. Pte Ltd, 2019) Gok K.; Gok A.; Kisioglu Y.
    Heat reveals during the bone drilling operations in orthopedic surgery because of friction between bone and surgical drill bit. The heating causes extremely important damages in bone and soft tissues. The heating has a critical threshold and it is known as 47C. If bone temperature value exceeds 47°C, osteonecrosis occurs in bones and soft tissues. Many factors such as surgical drill bit geometry and material, drilling parameters, coolant has important roles for the temperature rise. Many methods are used to decrease the temperature rise. The most effective method among them is to use the coolant internally. Numeric simulations of a new driller system to avoid the overheating during the orthopedic operating processes were performed in this study. The numerical simulation with/without coolant was also performed using the finite element based software. Computer aided simulation studies were used to measure the bone temperatures occurred during the bone drilling processes. The outcomes from the simulations were compared with the experimental results. A good temperature level agreement between the experimental results and FEA simulations was found during the bone drilling process. © 2019 World Scientific Publishing Company.
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    Development of bone chip-vacuum system in orthopedic drilling process
    (Springer Science and Business Media Deutschland GmbH, 2021) Gok K.; Erdem M.; Kisioglu Y.; Gok A.; Tumsek M.
    Overheating occurs during the bone drilling process using drill bits in orthopedic surgery. The temperatures frequently exceed 47 °C, usually accepted as critical value, since the bones and surrounding tissues burn and then cause the necrosis during the drilling process. To prevent this, orthopedic surgeons either spray coolants to the drilling zone or pause the drilling process until the bones and tissues cool down. Such heat damage in bones and soft tissues is undesirable event for surgeons. The bone chips, sometimes, are also complicating the bone fracture fixations. In this study, an investigation is described the effects of the processing parameters on bone chip formations, temperature levels and chip-vacuuming performances during drilling. The temperature levels are also measured using thermocouple devices. A bone chip collecting system is developed as a specific device to collect the chips or fragments using vacuuming technique. The collected bone chips are stored in a pot (reservoir) and delivered to a reparative site in case of necessary. Some design parameters for the developed vacuum system are identified considering the temperature rise during the drilling process. Analyzing the effects of these parameters on chip formation and developed vacuum system statistically and some results are presented. At the end of the study, the bone chip-vacuum device was developed and performed successfully to collect the whole fragments in the bone drilling experimental tests. The chip-collecting device was also useful to remove overheat from the drilling zone. The optimal level of the processing parameters was calculated as A1B3C1 for both vacuumed and non-vacuumed conditions. The fractured powder-type chips were formed as anticipated using the cortical structure of diaphyseal part of calf bone which is helpful for chip vacuuming device. © 2021, The Brazilian Society of Mechanical Sciences and Engineering.