scholarly journals Effect of Femoral Head Necrosis Cystic Area on Femoral Head Collapse and Stress Distribution in Femoral Head

2021 ◽  
Author(s):  
Zhikun Zhuang ◽  
Tianye Lin ◽  
Wenting Song ◽  
Yuan Zhong ◽  
Peng Yang ◽  
...  
Keyword(s):  
Femoral Head ◽  
Maximum Stress ◽  
Von Mises Stress ◽  
Necrotic Area ◽  
Mean Stress ◽  
Femoral Head Collapse ◽  
Cystic Area ◽  
Von Mises ◽  
Different Diameters

Abstract Objective: Osteonecrosis of the femoral head (ONFH) is a common and difficult disease. The effect of cystic area on femoral head mechanics in patients with ONFH is unknown. The purpose of this study was to investigate the effect of cystic areas of osteonecrosis of the femoral head on stress distribution and disease progression in the femoral head.Methods: A total of 85 patients (106 hips) diagnosed with ARCO stage II non-traumatic and non-surgical treatment of ONFH from February 2017 to November 2018 were retrospectively analyzed. All patients were followed up for an average of more than 2 years. According to whether the femoral head collapsed during the follow-up, they were divided into collapse group and non-collapse group. The age, gender, etiology, height, weight, BMI, JIC classification, presence of cystic areas and diameter of cystic areas were compared between the two groups. In addition, five spherical cystic areas of different diameters of 0, 5, 10, 15, and 20 mm were constructed to simulate the hip joint load of a person during standing by finite element methods, and the maximum stress, mean stress, and maximum stress values in the necrotic area of the femoral head without cystic areas and in the area 1 mm around the cystic areas with different diameters were observed and analyzed.Results: All 85 patients (106 hips) completed the follow-up, with an average age of 37.4 ± 8.12 years. The mean follow-up time was 2.8 ± 0.6 years. Forty-five patients (57 hips) with ONFH who had femoral head collapse were included in the collapse group, and the remaining 40 patients (49 hips) were included in the non-collapse group. There was significant difference in JIC classification between the two groups (P < 0.05), most of which were C2 type in the collapse group and B type in the non-collapse group. There was a difference between the two groups in whether cystic areas appeared in the femoral head, with 49.1% in the collapse group showing cystic areas, which was significantly higher than that in the non-collapse group (18.4%) (P < 0.05). In addition, the diameter of the cystic areas was significantly larger in the collapsed group than in the non-collapsed group (P < 0.05). The maximum von Mises stress value and mean von Mises stress value around the cortical bone, necrotic area and around the cystic area of the femoral head increased with the increase of the cystic diameter. Furthermore, linear regression analysis showed a linear positive correlation between the maximum stress, mean stress in the necrotic area in the femoral head, and the maximum stress value in the 1 mm area around the cystic area and the diameter of the cystic area.Conclusion: The maximum stress and average stress of necrotic area can be increased in cystic area, and the increase of stress in cystic area is more obvious. Stress concentration areas can be generated around the cystic areas. The presence and increased diameter of the cystic areas accelerates the collapse of the ONFH femoral head.

scholarly journals Effect of Femoral Head Necrosis Cystic Area on Femoral Head Collapse and Stress Distribution in Femoral Head

2021 ◽  
Author(s):  
Zhikun Zhuang ◽  
Tianye Lin ◽  
Wenting Song ◽  
Yuan Zhong ◽  
Peng Yang ◽  
...  
Keyword(s):  
Femoral Head ◽  
Maximum Stress ◽  
Von Mises Stress ◽  
Necrotic Area ◽  
Mean Stress ◽  
Femoral Head Collapse ◽  
Cystic Area ◽  
Von Mises ◽  
Different Diameters

Abstract Objective:Osteonecrosis of the femoral head (ONFH) is a common and difficult disease. The effect of cystic area on femoral head mechanics in patients with ONFH is unknown. The purpose of this study was to investigate the effect of cystic areas of osteonecrosis of the femoral head on stress distribution and disease progression in the femoral head.Methods:A total of 85 patients (106 hips) diagnosed with ARCO stage II non-traumatic and non-surgical treatment of ONFH from February 2017 to November 2018 were retrospectively analyzed. All patients were followed up for an average of more than 2 years. According to whether the femoral head collapsed during the follow-up, they were divided into collapse group and non-collapse group. The age, gender, etiology, height, weight, BMI, JIC classification, presence of cystic areas and diameter of cystic areas were compared between the two groups. In addition, five spherical cystic areas of different diameters of 0, 5, 10, 15, and 20 mm were constructed to simulate the hip joint load of a person during standing by finite element methods, and the maximum stress, mean stress, and maximum stress values in the necrotic area of the femoral head without cystic areas and in the area 1 mm around the cystic areas with different diameters were observed and analyzed.Results:All 85 patients (106 hips) completed the follow-up, with an average age of 37.4 ± 8.12 years. The mean follow-up time was 2.8 ± 0.6 years. Forty-five patients (57 hips) with ONFH who had femoral head collapse were included in the collapse group, and the remaining 40 patients (49 hips) were included in the non-collapse group. There was significant difference in JIC classification between the two groups (P < 0.05), most of which were C2 type in the collapse group and B type in the non-collapse group. There was a difference between the two groups in whether cystic areas appeared in the femoral head, with 49.1% in the collapse group showing cystic areas, which was significantly higher than that in the non-collapse group (18.4%) (P < 0.05). In addition, the diameter of the cystic areas was significantly larger in the collapsed group than in the non-collapsed group (P < 0.05). The maximum von Mises stress value and mean von Mises stress value around the cortical bone, necrotic area and around the cystic area of the femoral head increased with the increase of the cystic diameter. Furthermore, linear regression analysis showed a linear positive correlation between the maximum stress, mean stress in the necrotic area in the femoral head, and the maximum stress value in the 1 mm area around the cystic area and the diameter of the cystic area.Conclusion:The maximum stress and average stress of necrotic area can be increased in cystic area, and the increase of stress in cystic area is more obvious. Stress concentration areas can be generated around the cystic areas. The presence and increased diameter of the cystic areas accelerates the collapse of the ONFH femoral head.

SuperMeshing: A Deep Learning Method for Boosting Mesh Density in Numerical Computation Within 2D Domain

2021 ◽  
Author(s):  
Handing Xu ◽  
Zhenguo Nie ◽  
Qingfeng Xu ◽  
Xinjun Liu
Keyword(s):  
Numerical Computation ◽  
Spatial Resolution ◽  
Maximum Stress ◽  
Linear Mapping ◽  
Stress Fields ◽  
Von Mises Stress ◽  
Full Detail ◽  
Mesh Density ◽  
Novel Method ◽  
Von Mises

Abstract Due to the limit of mesh density, the improvement of the spatial resolution of numerical computation always leads to a decrease in computing efficiency. Aiming at this inability of numerical computation, we propose a novel method for boosting the mesh density in finite element method (FEM) within 2D domain. Based on the von Mises stress fields of 2D plane-strain problems computed by the FEM, this method utilizes a deep neural network named SuperMeshingNet to learn a non-linear mapping from low mesh-density to high mesh-density in stress fields, and realizes the improvement of numerical computation accuracy and efficiency simultaneously. We adopt residual dense blocks into our mesh-density boost model – SuperMeshingNet to extract abundant local features and enhance the prediction capacity. The results indicate that SuperMeshingNet is able to effectively increase the spatial resolution of the von Mises stress fields under the multiple scaling factors: 2X,4X,and8X. Compared with the targets, the relative error of SuperMeshingNet is 2.44%, which shows better performance than the interpolation methods. Besides, SuperMeshingNet reveals an astonishing strength in predicting the maximum stress value. We publicly share our work with full detail of implementation at https://github.com/zhenguonie/2021_SuperMeshing_2D_Plane_Strain.

scholarly journals Tympanic Membrane Collagen Expression by Dynamically Cultured Human Mesenchymal Stromal Cell/Star-Branched Poly(ε-Caprolactone) Nonwoven Constructs

2020 ◽  
Vol 10 (9) ◽  
pp. 3043
Author(s):  
Stefania Moscato ◽  
Antonella Rocca ◽  
Delfo D’Alessandro ◽  
Dario Puppi ◽  
Vera Gramigna ◽  
...  
Keyword(s):  
Tympanic Membrane ◽  
Maximum Stress ◽  
Element Model ◽  
Von Mises Stress ◽  
Type I ◽  
Collagen Types ◽  
Collagen Expression ◽  
Polymerase Chain ◽  
Von Mises ◽  
Membrane Collagen

The tympanic membrane (TM) primes the sound transmission mechanism due to special fibrous layers mainly of collagens II, III, and IV as a product of TM fibroblasts, while type I is less represented. In this study, human mesenchymal stromal cells (hMSCs) were cultured on star-branched poly(ε-caprolactone) (*PCL)-based nonwovens using a TM bioreactor and proper differentiating factors to induce the expression of the TM collagen types. The cell cultures were carried out for one week under static and dynamic conditions. Reverse transcriptase-polymerase chain reaction (RT-PCR) and immunohistochemistry (IHC) were used to assess collagen expression. A Finite Element Model was applied to calculate the stress distribution on the scaffolds under dynamic culture. Nanohydroxyapatite (HA) was used as a filler to change density and tensile strength of *PCL scaffolds. In dynamically cultured *PCL constructs, fibroblast surface marker was overexpressed, and collagen type II was revealed via IHC. Collagen types I, III and IV were also detected. Von Mises stress maps showed that during the bioreactor motion, the maximum stress in *PCL was double that in HA/*PCL scaffolds. By using a *PCL nonwoven scaffold, with suitable physico-mechanical properties, an oscillatory culture, and proper differentiative factors, hMSCs were committed into fibroblast lineage-producing TM-like collagens.

scholarly journals Pengembangan Alat Bantu Arbor untuk Pembuatan Roda Gigi pada Mesin Frais Vertikal

2021 ◽  
Vol 12 (2) ◽  
pp. 287-296
Author(s):  
Widodo Widodo ◽  
◽  
Rahman Hakim
Keyword(s):  
Metal Cutting ◽  
Engine Speed ◽  
Maximum Stress ◽  
Design Method ◽  
Machining Process ◽  
Von Mises Stress ◽  
Von Mises ◽  
Cutting Processes ◽  
Stress Simulation

The machining process is included in the classification of metal cutting processes, which are used to change the shape of metal or non-metallic product by cutting, peeling or separating. One of the machines used in this cutting process is a vertical type milling machine. This machine functions to make a product, one of which was a gear. The supporting equipment needed to make this gear was a vertical arbor tool. The material used in the manufacture of this product was a cast carbon steel type using the design method for manufacturing and assembly (DFMA), which began by examining and identifying needs, conceptualizing and designing products and making these products tailored to the dimensional specifications of standard and common cutter modules in the market. The results of the manufacture of this tool were directly tested for the manufacture of gears of various sizes and produced products whose deviations were within the tolerance of the measuring instrument, namely in the range 0 to 2%. In addition, the von Mises stress simulation at an engine speed of 150 Rpm, 450 Rpm and 750 Rpm and the resulting maximum stress was still below the yield limit, so it was safe to use.

scholarly journals Evaluation of Stress Distribution and Force in External Hexagonal Implant: A 3-D Finite Element Analysis

2021 ◽  
Vol 18 (19) ◽  
pp. 10266
Author(s):  
Vinod Bandela ◽  
Ram Basany ◽  
Anil Kumar Nagarajappa ◽  
Sakeenabi Basha ◽  
Saraswathi Kanaparthi ◽  
...  
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Stress Distribution ◽  
Maximum Stress ◽  
Axial Direction ◽  
Von Mises Stress ◽  
P Value ◽  
Implant Surface ◽  
Element Analysis ◽  
Von Mises

Purpose: To analyze the stress distribution and the direction of force in external hexagonal implant with crown in three different angulations. Materials and Methods: A total of 60 samples of geometric models were used to analyze von Mises stress and direction of force with 0-, 5-, and 10-degree lingual tilt. Von Mises stress and force distribution were evaluated at nodes of hard bone, and finite element analysis was performed using ANSYS 12.1 software. For calculating stress distribution and force, we categorized and labeled the groups as Implant A1, Implant A2, and Implant A3, and Implant B1, Implant B2, and Implant B3 with 0-, 5-, and 10-degree lingual inclinations, respectively. Inter- and intra-group comparisons were performed using ANOVA test. A p-value of ≤0.05 was considered statistically significant. Results: In all the three models, overall maximum stress was found in implant model A3 on the implant surface (86.61), and minimum was found on model A1 in hard bone (26.21). In all the three models, the direction of force along three planes was maximum in DX (0.01025) and minimum along DZ (0.002) direction with model B1. Conclusion: Maximum von Mises stress and the direction of force in axial direction was found at the maximum with the implant of 10 degrees angulation. Thus, it was evident that tilting of an implant influences the stress concentration and force in external hex implants.

scholarly journals A Comparative Biomechanical Analysis of Various Rod Configurations Following Anterior Column Realignment and Pedicle Subtraction Osteotomy

Neurospine ◽  
2021 ◽  
Vol 18 (3) ◽  
pp. 587-596
Author(s):  
Muzammil Mumtaz ◽  
Justin Mendoza ◽  
Ardalan Seyed Vosoughi ◽  
Anthony S. Unger ◽  
Vijay K. Goel
Keyword(s):  
Stress Reduction ◽  
Factor Of Safety ◽  
Maximum Stress ◽  
Element Model ◽  
Pedicle Subtraction Osteotomy ◽  
Biomechanical Analysis ◽  
Anterior Column ◽  
Von Mises Stress ◽  
Correction Technique ◽  
Von Mises

Objective: The objective of this study was to compare the biomechanical differences of different rod configurations following anterior column realignment (ACR) and pedicle subtraction osteotomy (PSO) for an optimal correction technique and rod configuration that would minimize the risk of rod failure.Methods: A validated spinopelvic (L1-pelvis) finite element model was used to simulate ACR at the L3–4 level. The ACR procedure was followed by dual-rod fixation, and for 4-rod constructs, either medial/lateral accessory rods (connected to primary rods) or satellite rods (directly connected to ACR level screws). The range of motion (ROM), maximum von Mises stress on the rods, and factor of safety (FOS) were calculated for the ACR models and compared to the existing literature of different PSO rod configurations.Results: All of the 4-rod ACR constructs showed a reduction in ROM and maximum von Mises stress compared to the dual-rod ACR construct. Additionally, all of the 4-rod ACR constructs showed greater percentage reduction in ROM and maximum von Mises stress compared to the PSO 4-rod configurations. The ACR satellite rod construct had the maximum stress reduction i.e., 47.3% compared to dual-rod construct and showed the highest FOS (4.76). These findings are consistent with existing literature that supports the use of satellite rods to reduce the occurrence of rod fracture.Conclusion: Our findings suggest that the ACR satellite rod construct may be the most beneficial in reducing the risk of rod failure compared to all other PSO and ACR constructs.

Investigation of Meniscus Effect on Microbond Test of Typha Fiber/Epoxy Matrix

2020 ◽  
Vol 402 ◽  
pp. 14-19
Author(s):  
Andri Afrizal ◽  
Ikramullah ◽  
Syarizal Fonna ◽  
Syifaul Huzni
Keyword(s):  
Epoxy Matrix ◽  
Maximum Stress ◽  
Interfacial Shear Strength ◽  
Von Mises Stress ◽  
Microbond Test ◽  
The Matrix ◽  
The Difference ◽  
Von Mises ◽  
The Impact ◽  
Fiber Radius

The microbond test was one of the methods to examine the interfacial shear strength (IFSS) value of fiber and polymer matrix. The meniscus angle that formed at both ends of the matrix is difficult to control while manufacturing the specimen for the microbond test. Therefore, the effect of meniscus angle must be evaluated. In this paper, we evaluated the impact of variations of the meniscus angle against the maximum von-mises stress and the IFSS value of the Typha fiber epoxy matrix by finite element method. The geometry of the microbond test specimen was modeled with 0.25 mm fiber radius, 2 mm fiber length, 1.75 mm embedded length of the matrix, and varied the meniscus angles with 22°, 30°, 45°, 60°, 75°, and 90°. The mesh type quad-dominated CAX4R is used on fiber and matrix, while quad COHAX4 is applied to the cohesive element between fiber and matrix. The constantly applied displacement was adjusted to the upper end of the fiber at 0.6 mm. The simulation results showed that the difference in maximum stress obtained in each model. Furthermore, that is not given much difference in IFSS value. It can be concluded that the meniscus angle affects the maximum von-mises stress but not too much-affected IFSS value of the fiber and epoxy matrix.

Course of Femoral Head Avascular Necrosis Without Femoral Head Collapse at Initial Examination: Minimum 8-Year Follow-Up

Orthopedics ◽  
2008 ◽  
Vol 31 (8) ◽  
pp. 1-4
Author(s):  
Rui Niimi ◽  
Akihiro Sudo ◽  
Masahiro Hasegawa ◽  
Atsumasa Uchida
Keyword(s):  
Femoral Head ◽  
Avascular Necrosis ◽  
Initial Examination ◽  
Femoral Head Collapse

Outcomes and indications of the single approach to double-channel core decompression and bone grafting with structural bone support for osteonecrosis of the femoral head

2021 ◽  
Author(s):  
Ju’an Yue ◽  
Xiaozhong Guo ◽  
Randong Wang ◽  
Bing Li ◽  
Qiang Sun ◽  
...  
Keyword(s):  
Femoral Head ◽  
Bone Grafting ◽  
Early Stage ◽  
Core Decompression ◽  
Harris Hip Score ◽  
Radiographic Evaluation ◽  
Femoral Head Collapse ◽  
Double Channel ◽  
Single Approach

Abstract BackgroundTo report the outcomes of the single approach to double-channel core decompression and bone grafting with structural bone support (SDBS) for osteonecrosis of the femoral head (ONFH) and define the indications.MethodsOne-hundred-and-thirty-nine hips in 96 patients (79 males, 17 females; mean age 37.53±10.31 years, range 14–58 years; mean body mass index 25.15±3.63 kg/m2) were retrospectively analysed. The Harris hip score (HHS) was used to assess hip function, and radiographs were used to assess the depth of femoral head collapse. Treatment failure was defined as the performance of total hip arthroplasty (THA). The variables assessed as potential risk factors for surgical failure were: aetiology, Japanese Osteonecrosis Investigation Committee (JIC) type, age, and Association Research Circulation Osseous (ARCO) stage. Complications were recorded.ResultsThe HHS increased from 79.00±13.61 preoperatively to 82.01±17.29 at final follow-up (P=0.041). The average HHS improvement was 3.00±21.86. The combined excellent and good rate at final follow-up (65.6%) was significantly higher than that before surgery (34.5%) (P=0.000). On radiographic evaluation, 103 (74.1%) hips remained stable, while 36 (25.9%) had femoral head collapse or aggravation of ONFH. THA was performed in 18 hips. Thus, the overall femoral head survival rate was 87.05% (121/139). The success rate was adversely affected by JIC type, but not by aetiology, age, or ARCO stage. The only complication was a subtrochanteric fracture in one patient.ConclusionThe SDBS effectively delays or even terminates the progression of ONFH, especially type B and C1. The SDBS is a good option for early-stage ONFH.

Finite Element Analysis on Structural Stress of 16×16 InSb IRFPA with Viscoelastic Underfill

2011 ◽  
Vol 314-316 ◽  
pp. 530-534 ◽  
Author(s):  
Li Wen Zhang ◽  
Jin Chan Wang ◽  
Qian Yu ◽  
Qing Duan Meng
Keyword(s):  
Finite Element ◽  
Maximum Stress ◽  
Viscoelastic Model ◽  
Finite Element Method Simulation ◽  
Von Mises Stress ◽  
Structural Stress ◽  
Element Analysis ◽  
Indium Bump ◽  
Final Yield ◽  
Von Mises

The thermal stress and strain, from the thermal mismatch of neighboring materials, are the major causes of fracture in InSb IRFPA. Basing on viscoelastic model describing underfill, the structural stress of 16×16 InSb IRFPA under thermal shock is studied with finite element method. Simulation results show that as the diameters of indium bump increase from 20μm to 36μm in step of 2μm, the maximum stress existing in InSb chip first increases slightly, and fluctuates near 28µm, then decreases gradually. Furthermore, the varied tendency seems to have nothing to do with indium bump standoff height, and with thicker indium bump height, the maximal Von Mises stress in InSb chip is smaller. All these mean that the thicker underfill is in favor of reducing the stress in InSb chip and improving the final yield.

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