Tibial fractures are a common type of long bone injuries, requiring solid fixation for quicker bone healing and functional recovery. Metallic plates, although widely use, have been associated to stress shielding due to their enhanced stiffness, which can prevent callus formation and adversely affect the long-term outcomes. This study develops and assesses composite bone plates reinforced with unidirectional carbon fibres in different stacking sequences, comparing their biomechanical performance with titanium plates through finite element (FE) analysis. A 3D model of the tibia with a 1 mm oblique fracture gap was reconstructed from scanned bone data and simulated under physiological axial loading (700 N). Stress distribution within cortical and cancellous bone, plates and screws, as well as axial and shear displacements at the fracture site, were analyzed. Results demonstrated that composite plates (particularly configurations C4, C10 and C11) exhibited higher stress transfer to bone and greater controlled fracture gap movements compared with titanium, thereby minimizing stress shielding and promoting favorable conditions for callus formation. Axial and shear displacements with carbon/epoxy plates were 88% and 48% higher, respectively, than titanium plates, without compromising fixation stability. These findings suggest that carbon fibre-reinforced composites offer a promising alternative to metallic implants by balancing flexibility and stability, though further validation with nonlinear material models, cyclic loading and clinical trials is required

Leaf springs serve as essential suspension elements; however, their steel construction contributes to a higher unsprung mass, ultimately diminishing overall efficiency. This investigation examines composite leaf springs as a lighter option, providing enhanced strength-to-weight ratio and performance. The findings underscore the ability to improve ride quality and decrease energy usage, positioning them as a feasible alternative to traditional steel springs. This paper presents the proposal and fabrication of a hybrid composite for the master leaf spring structure. Identifying and simplifying hybrid composite for the master leaf spring structure with well-balanced combination of high tensile strength, toughness, and lightweight properties. These springs incorporate carbon fiber, glass fiber, and Lantor Soric XF cores, providing impressive strength-to-weight ratios and outstanding fatigue resistance while minimizing weight. An integrated AHP-TOPSIS and FEA methodology was employed to enhance the optimization of composite leaf springs. The final laminate is composed of Carbon Fiber (-82 degrees, 1 mm), Glass Fiber (-55 degrees, 0.75 mm), Lantor Soric XF (0 degrees, 2 mm), Glass Fiber (+55 degrees, 1.25 mm), and Carbon Fiber (+82 degrees, 1 mm), determined by performance parameters such as equivalent stress and equivalent elastic strain. This investigation assesses the tensile and flexural properties. The tensile testing conducted according to ASTM D3039 indicated a UTS of approximately 23.5 MPa and a yield strength of around 8.38 MPa. The flexural testing conducted in accordance with EN ISO 14125 revealed a peak load of 0.270 kN and a transverse strength of 89.32 N/mm2. The findings indicate outstanding strength-to-weight characteristics, validating the composite's appropriateness for lightweight, load-bearing applications. The hybrid carbon-glass-foam laminate demonstrates a well-rounded combination of strength, toughness, and lightweight characteristics, positioning it as an excellent substitute for steel in automotive applications where weight is a critical factor, such as in leaf springs.

To facilitate the healing process in a tibia fracture, the fracture plate should have higher axial movement with lesser twist of the plate at the fracture site along with well-distributed lower stress in the plate and the bone. To achieve these attributes, carbon/epoxy fiber-reinforced laminated composite bone plate is studied as a transverse fractured human tibia shaft of 3-mm fracture gap. Taguchi design of experiment (DOE)-guided finite element analysis results of L32 orthogonal array are used by multi-criteria decision making (MCDM) techniques such as integrated fuzzy AHP–TOPSIS and find out the average performance index to achieve the desired stress distributions and movements. Taguchi optimization method is employed to find the fiber orientations of each lamina for achieving the target properties, which are validated further through finite element analyses. It is found that among the 32 DOE-guided simulations the experiment number 1 having stacking sequence of [−45°/−45°/−45°/−45°/−45°/−45°/−45°/−45°/−45°]S with 0.2 mm lamina thickness is ranked 1 for multi-criteria optimization considering average performance index 0.643106 which also has the maximum axial movement of value 0.291 mm and minimum stress on the plate with 84.378 MPa. Lesser value of stress on the cancellous bone (1.461 MPa) obtained in the exp. no. 32 with the layer orientation is [90°/90°/0°/−45°/45°/−45°/45°/90°/0°]s and thickness 2.5 mm. Lower value of twisting angle (0.3775658°) and stress (15.347 MPa) in cortical bone are obtained using Taguchi optimization method with the layer orientation of [90°/90°/90°/90°/90°/90°/90°/90°/90°]s and [90°/90°/90°/90°/90°/−45°/−45°/45°/45°]s having thickness of 2.5 mm.

Flatfoot is a very common condition that alters gait mechanics and is usually accompanied by pain. In this current study, two types of custom-made insoles using polyethylene and silicon, respectively, were designed to help alleviate this condition. Such insoles are tested for their functionality using advanced 3D printing and finite element analysis. Tests were conducted at body weights of 60, 80, 100, and 120 kg. Results indicated that silicone insoles outperformed the others by effecting a better redistribution of pressure with higher magnitudes of strain and stress. Specifically, silicon had strain values between 1.44 × 10 −7 and 2.88 × 10 −7 , much lower than polyethylene’s 5.92 × 10 −5 –1.18 × 10 −4 . Whereby, silicon would withstand stress levels to about 47,058 Pa, while polyethylene would do so at 31,932 Pa, making it more resilient under higher loads. Further validation through kinematic analysis proved that silicon insoles enhance the symmetry of walk and disperses the concentration of pressures of the feet, therefore providing more comfort and support during locomotion. These results suggest that silicon insoles offer significant benefits for managing flatfoot, paving the way for future innovations in personalized orthopedic footwear.

The spinal diseases commonly faced by people in the 19th century included intervertebral disc degeneration, tuberculosis and congenital defects that resulted in neurological impairment and global disability. To address these issues, cervical spine surgery was performed. Modern techniques currently used in spine surgery include interbody devices, pedicle screws, artificial discs and bone grafts. The postoperative complications clinically reported during follow-up include nonunion and implant subsidence, which remain significant drawbacks. The objective of this study is to develop a 3-dimensional finite element model of the C2-C7 cervical spine and validate it against existing experimental studies. The loading conditions considered for this study include a compressive preload of 50 N and a 1 Nm moment applied to the C2 vertebra, with the C7 vertebra fixed at the bottom. In this study, the biomechanical alterations of 4 different cage morphologies were analysed using finite element analysis. Valeo cages with 4 distinct designs were implanted at the C5-C6 level, and physiological motion at the surgical site was studied. Cage subsidence and migration, which can lead to adjacent segment disc degeneration, were also examined. Subsidence was primarily attributed to higher stress encountered in the cage, so stress distribution within the cages was evaluated. Additionally, stress distribution in the anterior plate and screws was analysed. The study concludes that introducing anterior plate and screw fixation helps prevent cage subsidence. Physiological motion at the surgical level was reduced compared to the intact model. Adjacent disc stress was also evaluated and found to be lower than in the intact model.

STUDY DESIGN:Basic research. PURPOSE:This finite element (FE) analysis (FEA) aimed to compare the biomechanical parameters in multilevel posterior cervical fixation with the C7 vertebra instrumented by two techniques: lateral mass screw (LMS) vs. transpedicular screw (TPS). OVERVIEW OF LITERATURE:Very few studies have compared the biomechanics of different multilevel posterior cervical fixation constructs. METHODS:Four FE models of multilevel posterior cervical fixation were created and tested by FEA in various permutations and combinations. Generic differences in fixation were determined, and the following parameters were assessed: (1) maximum moment at failure, (2) maximum angulation at failure, (3) maximum stress at failure, (4) point of failure, (5) intervertebral disc stress, and (6) influence of adding a C2 pars screw to the multilevel construct. RESULTS:The maximum moment at failure was higher in the LMS fixation group than in the TPS group. The maximum angulation in flexion allowed by LMS was higher than that by TPS. The maximum strain at failure was higher in the LMS group than in the TPS group. The maximum stress endured before failure was higher in the TPS group than in the LMS group. Intervertebral stress levels at C6-C7 and C7-T1 intervertebral discs were higher in the LMS group than in the TPS group. For both models where C2 fixation was performed, lower von Mises stress was recorded at the C2-C3 intervertebral disc level. CONCLUSIONS:Ending a multilevel posterior cervical fixation construct with TPS fixation rather than LMS fixation at the C7 vertebra provides a stiff and more constrained construct system, with higher stress endurance to compressive force. The constraint and durability of the construct can be further enhanced by adding a C2 pars screw in the fixation system.

For the purpose of fixing tibia fractures, composite bone plates are suggested. Metal plates cause stress shielding, lessen the compression force at the fracture site, and have an impact on the healing process because they are significantly more rigid than bone. To prevent excessive shear strain and consequent instability at the fracture site, it is imperative to reduce stiffness in the axial direction without lowering stiffness in the transverse direction. Only a carefully crafted fiber reinforced composite with anisotropic properties will suffice to accomplish this. The purpose of the current study is to examine the impact of axial and shear movements at the fracture site on the fixing of metal and composite bone plates. After modeling the tibia with a 1 mm fracture gap, titanium plates, carbon/epoxy, carbon/PEEK, and carbon/UHMWPE composite bone plates were used to fix it. There are 6 holes on each of the 103 mm long plates. To determine the stresses and axial movement in the fracture site, anatomical 3D Finite Element (FE) models of the tibia with composite bone plates are built. The simulations that were run for various composite plate layouts and types give suggestions for selecting the best composite bone plate. Although the matrix material causes some variations in behaviors, most of the plates perform as well as or even better than metal plates. Thus, the appropriate composite combinations are recommended for a given fracture structure.

Study Design: Basic research. Purpose: This finite element (FE) analysis (FEA) aimed to compare the biomechanical parameters in multilevel posterior cervical fixa-tion with the C7 vertebra instrumented by two techniques: lateral mass screw (LMS) vs. transpedicular screw (TPS). Overview of Literature: Very few studies have compared the biomechanics of different multilevel posterior cervical fixation constructs. Methods: Four FE models of multilevel posterior cervical fixation were created and tested by FEA in various permutations and com-binations. Generic differences in fixation were determined, and the following parameters were assessed: (1) maximum moment at failure, (2) maximum angulation at failure, (3) maximum stress at failure, (4) point of failure, (5) intervertebral disc stress, and (6) influ-ence of adding a C2 pars screw to the multilevel construct. Results: The maximum moment at failure was higher in the LMS fixation group than in the TPS group. The maximum angulation in flexion allowed by LMS was higher than that by TPS. The maximum strain at failure was higher in the LMS group than in the TPS group. The maximum stress endured before failure was higher in the TPS group than in the LMS group. Intervertebral stress levels at C6-C7 and C7-T1 intervertebral discs were higher in the LMS group than in the TPS group. For both models where C2 fixation was performed, lower von Mises stress was recorded at the C2-C3 intervertebral disc level. Conclusions: Ending a multilevel posterior cervical fixation construct with TPS fixation rather than LMS fixation at the C7 vertebra provides a stiff and more constrained construct system, with higher stress endurance to compressive force. The constraint and dura-bility of the construct can be further enhanced by adding a C2 pars screw in the fixation system

Optimal composite bone plate is designed for Periprosthetic Femoral Fracture (PFF) fixation using genetic algorithm (GA) by hybrid and varying fiber orientation. The bone plate should allow higher displacement in axial direction and minimum movement in shear direction. Composite material is considered for the bone plate, the most important constraint in this design problem is that the axial movement and shear movement are limited to 2 and 0.5 mm, respectively. The simulated data from the finite element analysis (FEA) are used for creating the artificial neural network (ANN) surrogate models for the bone displacements in both the directions, which act as the objective functions for the GA-driven optimization in the multi-objective fashion. FEA is used to validate the solutions derived through the design optimization process. The FE simulations have shown only 10% deviation in the simulation output when compared to the achieved optimum solutions.

This study aims to develop a patient-specific hip implant for osteoarthritis conditions and to compare with intact and conventional implant. The femoral bone with head and shaft region was segmented from the pelvic griddle and converted into 3D model. The parameters such as femoral ball diameter, shaft length, acetabular cup diameter, and neck angle were measured from the segmented 3D model. In this study, designed part of hip implant was assembled together to form a customized hip implant. The von Mises stress was measured by means of Finite element analysis (FEA) method by applying various forces applied at the distal end of hip implant. The forces applied at hip implant were based on the assumption of 500 N force for standing, 2000 N force for walking, and 3000 N force for jogging condition. The minimum stress attained at the femur bone of custom-model is 1.32 MPa for 500 N loading condition, 5.3 MPa for 2000 N and 7.96 MPa for the maximum load of 3000 N. Thus the customized model experienced better stress distribution compared to conventional model under the maximum load of 3000 N. In pelvic region, the custom model attained a lower stress of 23% compared to conventional model. Thus, the study recommends the customized hip implants for the osteoarthritis conditions to avoid revision surgery.

Conventional stainless steel or titanium plates are used for bone fracture fixation to provide support at fracture location. Plates with high elastic modulus reduce the transfer of compressive load at the fracture location (due to stress shielding), causing failure. The objective of the study is to find for composite bone plates with different types of fibers and varied fiber orientations for post-operative (PO) and healed bone (HB) conditions which can reduce the stress shielding. Femur fracture fixation was constructed with 12 holes narrow type with metal and composite bone plates. The fracture gap was constructed with soft bone region for post-operative (PO) condition and harder bone for healed bone (HB). Composite bone plates with different configurations (fiber directions) and types (thickness and width) were analyzed to study the stress distribution and movement in the fracture location. The models were analyzed and the stresses in plate and callus, movement and strain in axial and shear direction in both metal and composite bone plates were studied. The metal and composite plates (carbon fiber/epoxy, fiberglass/epoxy, and flax/epoxy) used for most common Vancouver type B1 fracture to observe the biomechanical behavior of different models in PO and HB condition. The FE simulation on different configurations and types of composite plates provide in-depth idea about choosing the suitable composite bone plate. There are variations in behavior for varying types and configurations, but the performance of most of the plates are either better or similar to that of metal plate, except the plates with higher width.

After total hip arthroplasty (THA), high demands occur in the femoral fixation, especially for elderly patients due to periprosthetic fractures. Fractures happened in the femur after THA was classified based on Vancouver periprosthetic femoral fracture. Choosing the fixation for these types of specific fracture types are challenging due to pattern and orientation of the fracture in the THA prosthesis. Several researchers have reported the clinical, experimental, and computational studies about the failure of fixation methods, and they highlighted the remedies and scope in the further studies. Most of the authors recommended the computational studies having the advantage to predict the inner behaviour of the bone because invivo/invitro study availability of the specimen are limited and it needs ethical clearance. The current study focussed on computational studies in periprosthetic fractures and aims to discuss the three dimensional model creation, mesh generation, material properties, boundary conditions/loading, limitation, opinions, and future thoughts in implant design.

The design optimization concept was employed to enhance the subsidence and circumvent post-surgical migration of cervical cages, which are placed between vertebrae filled with bone to facilitate cervical commixture. Finite-element analysis (FEA) was used to design cervical cages of various shapes and sizes, in which a poly-ether-ether-ketone (PEEK) hybrid composite was used as the material for the cervical cages. Stress analysis was performed with the cage placed between cervical vertebrae C3 and C4 to find the maximum von Mises and shear stresses acting on the cage of varied dimensions and material properties. A multi-objective genetic algorithm was used to find the optimum design of the cage with minimized maximum von Mises and shear stresses to achieve improved subsidence and resistance to migration. Artificial neural network (ANN) metamodels emerged for the stress analysis using FEA simulation data. Another ANN model was used to map different reinforcement particles with the elastic modulus of the PEEK composite, which acted as one of the inputs in the first ANN model. This two-level ANN model was used as the objective function for the optimization. Pareto solutions were analyzed to obtain an in-depth idea of the optimum solutions.

The major concern after total hip arthroplasty (THA) is the incidence of periprosthetic fracture in the weaker bone, which can lead to subsequent revision surgery. Achieving the suitable fixation without affecting the stability of the well-fixed prosthesis remains controversial. Most of the studies examined the behavior of the Periprosthetic Fracture (PF) fixation (Vancouver “B1” type) through computational and experimentation on healthy bone condition with metal plates. The aim of the present study is to analyze the influences of the metal and composite bone plate PF fixation on the axial and shear movement at the fracture site. The PF fixation constructs were modeled with medical graded stainless-steel plate (construct A), titanium plate (construct B) and carbon/epoxy composite bone plate (construct C) with 12 holes and a 4 mm fracture gap. Analysis was carried out for all the stages (stage 1—Normal bone, stage 2—THA, stage 3—Immediate Post-Operative (IPO), stage 4—Post-Operative (PO) and, stage 5—Healed Bone (HB)) under various loadings for intact and osteoporosis conditions. The results showed higher stress in cortical bone for stage 3, whereas in all the other stages lower stresses were experienced in the cortical and cancelous bone under peak load in construct C for osteoporosis model compared with other constructs. The present study suggested the construct C may be suitable for osteoporosis bone conditions.

Background and objectives: Composite bone plates are proposed for fracture fixation in periprosthetic femoral fracture. Metallic plates, having high stiffness compared to bone lead to stress shielding, reduce the compression force in the fracture site, affectthe healing process. Reduction of stiffness in the axial direction due to above reason without lowering the stiffness in transverse to avoid much of shear strain and thus avoiding instability at the fracture site leads to selective stress shielding. This can only be achieved through meticulously designed fiber reinforced composite. In the present work varied fiber orientations in the stacked laminates with varied fiber types are employed in a post-operative femur fixation for the in-silico analyses of their effectiveness using finite element analysis. Methods: In this study a Total Hip Arthroplasty (THA) model is constructed with composite bone plates. Three-dimensional narrow type metal plate is modeled with 12 holes and length of 194 mm. Three different types of composite bone plates are modeled with 12 holes of different size for the analysis i.e. Type 1 (5.6 mm thickness and 16 mm width), Type 2 (6 mm thickness and 16 mm width) and Type 3(6 mm thickness and 18 mm width). Anatomical 3D FE models of THA with composite bone plates are constructed to find out the interfacial stresses and strains. The finite element software ANSYS is used to perform the analysis. Results: A three-dimensional FE model of immediately post-operative femur fixation is developed and studied the maximum stress distribution, strain and movement in axial/shear direction in the metal and composite bone plate near to the fracture site. In the present study, the metal and composite plate (carbon/epoxy, glass/epoxy and flax/epoxy) used for most common Vancouver type B1 fracture to observe the biomechanical behavior of different models in IPO condition using FEA. Conclusions: Optimizing the fiber orientations of composite bone plates of Total Hip Arthroplasty (THA) model by controlling the biomechanical stresses could be a favorable approach. The finite element analysis approach gives a viable solution to design the composite bone plate and for designing future models that preserves the biomechanical function of THA with composite bone plate. (C) 2020 Elsevier B.V. All rights reserved.

The aim of using circular implants is to produce additional skin in healthy parts of the body, so that new skin that is produced may be used to aid in healing injured areas that occur with plastic surgery. This study shows the amount of additional skin that is produced over time from implants, corresponding to the amount of liquid that is inside the implant membrane. The authors perform the study first on implants alone and then we place implants under the skin. Results of the first step are in agreement with previously conducted research. Second-step results are the first of their kind, because to the best of our knowledge, no similar studies have been conducted, either experimentally or numerically. Our study is motivated by wavering and inconsistent results that are obtained during real-time surgical procedures.

BACKGROUND:Symptomatic or asymptomatic transitional anomalies at the lumbosacral junction are common occurrences in the population. Lumbosacral (L5-S1) accessory articulations are the most common presentations of transitional anomalies at this region. Such anatomical alterations are believed to be associated with biomechanical changes of load-bearing and movement restrictions leading to low back pain. This study attempts to use computational models of a normal and a lumbosacral transitional vertebrae (LSTV) accessory articulation to analyze and compare the range of motion and loading patterns at the lumbosacral articulations.METHODS:Three-dimensional Finite Element computational models of normal and accessory L5-S1 articulated sacrum were created. These models were tested for range of motion and stress patterns generated at the lumbosacral articulations using similar loading and motion simulation to elicit different moments/excursions at the lumbosacral junctions.RESULTS:Compared to the normal variant, the transitional model exhibited different range of motion and divergent patterns of stress generation at the lumbosacral and accessory articulations with equal and physiological magnitudes of loading applied to both the models.CONCLUSIONS:The finite element modeling approach can be used for biomechanical investigations in LSTV variants. However, larger sample studies with different LSTV models may be required to statistically compare movement and loading patterns at LSTV-affected lumbosacral and sacroiliac junctions, and to recommend definitive treatment strategies in these situations.

Sacralization is a type of transitional abnormally observed at the lumbosacral junction. It involves fully bilateral fusion in between the fifth lumbar vertebra to first sacral vertebra (L5–S1 Transverse vertebra). Sacralization of the L5 vertebra is more commonly observed in people comparison to lumbarization of the first sacral vertebra segment, this can be present in human being from birth. The aim of the present work is to study the pressure distributions in sacralisation. For that cadaveric bones of sacralisation are used to measure geometrical data for modeling and to construct a better mesh representation for sacralization, the meshed model was analysed under compressive load to understand the load concentration on the sacralization. It is observed that the pressure distributions of the ventral lateral and dorsal-medial sides of sacrum are slight higher when compare to ventral and dorsal sides. This stresses were mostly concentrating at the sacral ala and the s1 pedicle region. This concentration may lead to fracture in ventral – lateral region of sacralization.

Objectives: To model and analyze the osteoporotic lumbar vertebra L2-L4 region and predict the stress patterns for different loading condition. Methods: Osteoporosis is a disease in which low bone mass density and micro deterioration of bone tissue causing bone fragility and high risk of fracture. Using the dry bone, the dimensions are measured and are compared with the literature dimensions. Based on these dimensions L2-L4 lumbar vertebral segment was modeled and meshed. Finite element model was developed to analyze the biomechanical properties of the vertebral body because of its complex anatomy. Findings: Intact model is validated for various range of motions and compared with the literature. Displacement in the end plates of vertebra are found and compared with the intact model. Applications: Implant for the osteoporosis patient can be designed using this Biomechanical study and can be analyzed for different loading conditions. Keywords: Endplates, Finite Element Analysis, Lumbar Vertebra, Osteoporosis

Starch metabolism due to adsorption of enzyme amylase on the starch substrate is outlined briefly. To explore the necessary conditions required for effective adsorption in biological media, ultrasonic techniques have been applied to elucidate the structural variations and component destruction in the considered systems. The ability of the enzyme amylase to break the linkages in starch (substrate) was determined from the observed ultrasonic velocity, which highlights the deciding factors of metabolism. It is concluded that the phenomenon of adsorption is decided by the surface area, the number of subunits held by the substrate, and the structure existing in the adsorbent, and above all, a relatively higher quantity of enzyme and the substrate.