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Typical finite-element meshes for the radius, the fixationplate implant and six screws used in the quasi-static analysis of the implant longevity
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The problem of optimal size, shape, and placement of a proximal radius-fracture fixation-plate is addressed computationally
using a combined finite-element/design-optimization procedure. To expand the set of physiological loading conditions experienced
by the implant during normal everyday activities of the patient, beyond those typically covered b...
Context in source publication
Context 1
... The Model. The finite element model analyzed consisted of a fractured right radius, a fixation-plate implant, and six locking screws. Typical finite element meshes used are displayed in Fig. 5. The radius, the plate, and each of the screws were discretized using ca. 13,000 ten-node second-order tetrahedral solid elements, ca. 2,200 twenty-node second-order brick elements, and ca. 200 twenty-node second-order brick elements, ...
Citations
... KBE systems and structural optimization are widely used for the development and optimization of fixation devices and implants [12][13][14]. External fixation device is a medical device which is used to immobilize bone fraction using pins, which goes inside and through bone, and which is externally connected to external mounting. There are a lot of design, biomechanical and manufacturing constrains which must be fulfilled in the design of external fixation device. ...
... The full numerical structural analysis of external fixation device, except the analysis of displacements at fracture gap, includes also the analysis of principal stress at characteristic places of design [14,20]. During FEM and experimental analysis, values and directions of principal stress are calculated at two control places at the middle part of the fixator tree. ...
The development process of the knowledge-based engineering (KBE) system for the structural size optimization of external fixation device is presented in this paper. The system is based on algorithms for generative modeling, finite element model (FEM) analysis, and size optimization. All these algorithms are integrated into the CAD/CAM/CAE system CATIA. The initial CAD/FEM model of external fixation device is verified using experimental verification on the real design. Experimental testing is done for axial pressure. Axial stress and displacements are measured using tensometric analysis equipment. The proximal bone segment displacements were monitored by a displacement transducer, while the loading was controlled by a force transducer. Iterative hybrid optimization algorithm is developed by integration of global algorithm, based on the simulated annealing (SA) method and a local algorithm based on the conjugate gradient (CG) method. The cost function of size optimization is the minimization of the design volume. Constrains are given in a form of clinical interfragmentary displacement constrains, at the point of fracture and maximum allowed stresses for the material of the external fixation device. Optimization variables are chosen as design parameters of the external fixation device. The optimized model of external fixation device has smaller mass, better stress distribution, and smaller interfragmentary displacement, in correlation with the initial model.
... At the same time, topology optimization method was also widely applied in the design of the plate. Using the size and shape parameters, design users can optimize the proximal radius fracture steel plate, and modify the outer shape of the design area [4] . The above studies focus on the assessment of the femoral fracture position and the mechanical performance of the plate, however, the information of the femur and fracture of a particular patient were ignored. ...
The mechanical environment of fractured bone after plate implanting is one of the important indicators to evaluate the plate design. In this paper, a novel method of plate editing based on stress analysis was proposed. With CT scans, the finite element analysis model of fracture plate and individual femur was constructed, then the characteristic shape of the plate was modified to improve the mechanical distribution of the plate by parametric feature shape editing. Experiments show that the proposed method has the advantages of simple and efficient, clear operation semantics.
... Experimental results show that the mechanics of fixation plate could be optimized [Stoffel, Dieter, Stachowiak et al. (2003)]. Based on that, optimization algorithms, and optimal size, shape and position of proximal radius fracture plate under physiological load conditions were proposed to improve the optimization efficiency [Grujicic, Xie, Arakere et al. (2010)]. Recently, a plate optimization method based on the material removal method (ERM) was proposed [Akif and İbrahim (2013)], in which plate material was recursively reduced by eliminating the lower region in FEA to optimize the topology of tibia plate. ...
... Experiment results show that the proposed plate optimization method can improve the stability and biomechanical properties of fracture segments, both in the aspect of fracture displacement and in the static stress of plate. Compared with the existing method [Grujicic, Xie, Arakere et al. (2010), Akif and İbrahim (2013), Zhang, Ebraheim, Ming et al. (2015), Manić, Stamenković, Mitković et al. (2015)], the proposed method has two technical advantages. ...
Shape optimization of orthopedic fixation plate is of great importance in the treatment of complex fracture. Therefore, a method in this paper to automatically optimize the complex shape of anatomical plate according to static analysis. Based on the theory of finite element analysis (FEA), our approach is processed as follows. First, the three-dimensional finite element model of the fracture fixation is constructed. Next, according to the type and feature of fracture, the anatomical plate was parameterized in two levels (the bounding surface and plate model). Then, parameter constraints are set up to meet the needs of surgical fracture treatment. Finally, by using the theories combined with the method of moving asymptote (MMA) and gradient projection (GP), the plate model is modified automatically based on the principle of plate stress and segment offset minimization. Experimental results show that the displacement of femur segments and the stress of fracture site were decreased slightly and can improve the biomechanical environment around the fracture.
... Although several works have been reported for the use of intelligent design in healthcare implants, most of them are based on hard tissues like orthopedic or dental implants [10,11]. To the authors' best knowledge; there have not been any studies on the design optimization of soft tissue implants to date. ...
Medical implants are usually mass produced in fixed sizes, shapes and material properties. However, this process is not sustainable due to high levels of material wastage resulting from unused products because of the low demand of particular sizes. Furthermore, these modular implants are not optimized to specific patient's anatomy in terms of geometry, material composition and properties. This often leads to risk of injury, implant displacement, impairment of intended functions or even rejection by the host body, thus contributing to further healthcare costs, implants wastage and discomfort to patient. We have been investigating patient-specific design methods to tailor implant design and material composition to the patient's anatomy. With patient-specific implant modeled and simulated, rule-based methods, Genetic Algorithm (GA) and material knowledge bases are used to perform multi-objective optimization of the material composition for additive manufacturing. This method is investigated with reference to the design and fabrication of a patient-specific ENT implant.
... The results indicated that the optimum thickness of a Ti alloy fractured-femur fixation plate implant is approximately 4.07 mm. The previous technique has also been used for addressing the optimal size, shape and placement problem of a proximal radius-fracture fixation plate [14]. ...
In previous work by Fouad (Medical Engineering and Physics 2010 [23]), 3D finite element (FE) models for fractured bones with function-graded (FG) bone-plates and traditional bone-plates made of stainless steel (SS) and titanium (Ti) alloy were examined under compressive loading conditions using the ABAQUS Code. In this study, the effects of the presence of the torsional load in addition to the compressive load on the predicted stresses of the fracture fixation bone-plate system are examined at different healing stages. The effects on the stress on the fracture site when using contacted and non-contacted bone-plate systems are also studied. The FE modelling results indicate that the torsional load has significant effects on the resultant stress on the fracture fixation bone-plate system, which should be taken into consideration during the design and the analysis. The results also show that the stress shielding at the fracture site decreases significantly when using FG bone-plates compared to Ti alloy or SS bone-plates. The presence of a gap between the bone and the plate results in a remarkable reduction in bone stress shielding at the fracture site. Therefore, the significant effects of using an FG bone-plate with a gap and the presence of torsional load on the resultant stress on the fracture fixation bone-plate system should be taken into consideration.
This study investigates visualization of optimized layer thickness with a ternary diagram by considering Volume, Weight, and Cost priorities to determine the composite structure of alternative ceramics to use in body armor application by using the Digital Logic Method (DLM). Three criterion priorities (volume, weight, cost) have been investigated to help designers decide on optimum ceramic material for their applications. Alumina (Al 2 O 3 ), silicon carbide (SiC), silicon nitride (Si 3 N 4 ), and boron carbide (B 4 C) were analyzed and ranked to decide for material selection based on priorities. The analysis results showed that silicon nitride (Si 3 N 4 ) had the maximum performance index (PI) point (80.0) based on the volume priority. On the other hand, while boron carbide (B 4 C) had the maximum PI point (76.4) in terms of the weight priority, alumina (Al 2 O 3 ) was determined to be the best material according to the cost priority. PI point of alumina (Al 2 O 3 ) was calculated as 100. A ternary diagram was developed for decision-makers to visualize material selection performances. The optimization of the ceramic composite layer thickness of the alternative ceramic materials is visualized by considering three criteria.
The objective of this study was to produce a methodology for designing multi-materials. This methodology was to be applied to an electronic embedded packaging structure for the aeronautics field. The reference material used for the electronic packaging was substituted for a multi-material able to combine the benefits of both material and architecture in order to enhance performance. The design of the multi-material was based on a coupled selection of materials and architectures performed using materials and geometrical pattern databases. The methodology provided both the optimal design in response to specifications and a large diversity of optimized designs (in terms of architectures and materials) relevant for the conceptual design stage. First, the optimal design of the electronic packaging was determined using a genetic algorithm. Next, the built approach integrated a hybridization of the genetic algorithm with a backtracking algorithm in order to propose optimized designs in a controlled time. Finally, the search space was modified by removing optimal designs previously identified by the genetic algorithm in order to determine a wide diversity of optimized designs.
This research is to evaluate and identify the most suitable implants for the treatment of trochanteric fractures. Using finite element analysis method (FEM), we developed trochanteric-fractured 3D models based on Arbeitsgemeinschaft für Osteosynthesefragen (AO) classification. Three types of trochanteric fractured models were assembled with four different implants leading to 12 models. The trochanteric fractures were identified as 31-A1.1, 31-A2.1, and 31-A3.1 fracture fixed with short proximal femur nail antirotation (PFNA), long PFNA, dynamic hip screw (DHS), and PF-locking compression plate 4.5/5.0. The assembled models were calculated and analyzed using the FEM. The simulation illustrated the von Mises stress distribution and displacement on 12 models. The intramedullary nail implant is superior to the external plate. Short PFNA and DHS are suitable to fix pertrochanteric fractures; long PFNA is considered a priority to treat intertrochanteric fractures.
To the Editor,We would like to thank Dr. Modenese and colleagues for taking the time to discuss our article “Consistency Among Musculoskeletal Models: Caveat Utilitor”.6 We would also like to thank those same researchers for making the model developed by their group, the London Lower Limb Model (LLLM),5 available to the musculoskeletal modeling community. After reviewing their analysis, we do agree with the LLLM researchers that the large discrepancy in quadriceps muscle recruitment (Fig. 4 in our original article) produced from their model as compared with the other models that were analyzed was primarily related to the fact that “neither contraction dynamics nor force-length-velocity relationships were implemented for the muscle actuators”5 in their model.The intent of our original analysis was not to misrepresent the LLLM model. The intent was to employ the models in canonical analyses shared by their respective software and advise future model users. As the purpose of the original ...
Application of topology optimization to fixation plates is the main consideration of this paper. The interbody fusion plates are required to give mechanical support to tibia with minimally invasive surgical procedure. Topology optimization is used to obtain fixation plates with possible minimum material usage. Topology optimization is applied to three types of plates which are used in upper tibial osteotomy. Initial design of the plates are first numerically modelled and then investigated for stresses under possible highest load values. The results of the analysis indicated that the plates are very stiff even under high loads. Application of topology optimization to plates yielded minimized weight and material usage while keeping the plates still adequate for possible high load values. It was also revealed that up to 50% of mass could be saved by an optimal implant design.
