scholarly journals Ratio of the Medial Hip Joint Space as a Predictor for Collapse of the Femoral Head in Non-traumatic Osteonecrosis: A Retrospective Study and Finite Element Analysis

2020 ◽  
Author(s):  
Tianye Lin ◽  
Peng Yang ◽  
Hongzhu Li ◽  
Jingli Xu ◽  
Binglang Xiong ◽  
...  
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Femoral Head ◽  
Cortical Bone ◽  
Hip Joint ◽  
Maximum Stress ◽  
Survival Rates ◽  
Element Analysis ◽  
Space Ratio

Abstract Background: There has been no indicators that can effectively predict femoral head collapse in ONFH so far. The aim of this study is to retrospectively analyze the first-visit medial space ratio of the hip joint to evaluate its efficacy in predicting ONFH-induced collapse and impacts on the mechanical environment of necrotic femoral head.Methods: In this retrospective analysis for traditional Chinese medicine (TCM), non-traumatic osteonecrosis of femoral head (NONFH) patients from January 2010 to December 2016 were selected. The medial space ratio at their first visit and and collapse of the femoral head during the follow-up were recorded. Patients were divided into group A, B, C, D, and E according to the grading of the medial space ratio at the first visit. A total of 14 hip joint models with distinct medial space ratios were established. The maximum stress intensities of the cartilage, cortical bone and the necrotic area (N-unit area) of the femoral head in the models were quantitated using a finite element analysis.Results: One hundred twenty-eight patients (142 hips) were included in this study. The average follow-up time was 5.4±1.5 years.The Kaplan-Meier survival analysis showed that survival rates of the first-visit medial space ratios in group C and D were significantly higher (exceeding 45.76%) than that in group E (22.73%). There was no significant difference in the survival rates between group C and D (P > 0.05). The finite element analysis showed that in either the necrosis or non-necrosis group, the maximum stress in cartilage, cortical bone and the N-unit area of the femoral head increased with the medial space ratio decreasing. Conclusion: The medial space ratio shows clinical implications of predicting the collapse of NONFH except for assessing the relationship between the femoral head and the acetabulum. The stress concentrations of cartilage, cortical bone, and the necrotic area of the femoral head are enhanced with the medial space radio decreasing. Once the medial space ratio falls below 4 and continues to decline, the risk of necrotic collapse will become higher.

scholarly journals Allograft Fibula Combined with Cannulated Screw for Femoral Head Necrosis: A Finite Element Analysis

2021 ◽  
Author(s):  
Gan Zhao ◽  
Ming Liu ◽  
Bin Li ◽  
Tianye Lin ◽  
JingLi Xu ◽  
...  
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Femoral Head ◽  
Cortical Bone ◽  
Maximum Stress ◽  
Weight Bearing ◽  
Cannulated Screw ◽  
Element Analysis ◽  
Osteonecrosis Of Femoral Head ◽  
Weight Bearing Area

Abstract Background: Osteonecrosis of femoral head (ONFH) is characterized by high incidence and disability. Allograft fibula combined with cannulated screw has been extensively applied for treating Osteonecrosis of femoral head. However, its biomechanical outcomes remain unclear. The present study aimed to investigate the optimal placement of the allograft fibula and cannulated screw for treating ONFH.Methods: Two types (C1 and C2) of NONFH finite element models were built based on a healthy subject and the Japanese Investigation Committee (JIC) classification system. The allograft fibula combined with cannulated screw was simulated in the respective type of the model. Different models were built by complying with the different positions of allograft fibula and cannulated screw (below model, posteriorly below model, anteriorly below model and anteriorly above model). Furthermore, a comparison was drawn on the maximum stress value and the mean stress value of the subchondral cortical bone of femoral head weight-bearing area.Results: As indicated from the finite element analysis, normal femoral head, necrotic femoral head and postoperative femoral head achieved the different maximum stress values, and the maximum stress value achieved by necrotic femoral head significantly reached over that of normal femoral head. After the operation, the maximum stress value of subchondral cortical bone in the weight-bearing area of the femoral head was noticeably down-regulated compared with that before the operation (necrotic femoral head). When the cannulated screw was directly below the fibula, subchondral cortical bone in the weight bearing area of femoral head achieved the smallest maximum stress value and average stress value, which showed a statistical difference from those of other models (P<0.05).Conclusion: Allograft fibula combined with cannulated screw is capable of significantly reducing the stress of subchondral cortical bone in the weight-bearing area of the ONFH femoral head, as well as down-regulating the stress concentration in the ONFH weight-bearing area. For JIC C1 and C2 osteonecrosis of the femoral head, when administrated with allograft fibula combined with cannulated screw, the optimal biomechanics was the cannulated screw located just directly below the fibula.

Finite Element Analysis of Multi-Implant Surgery for a Large Area of Defects

2014 ◽  
Vol 563 ◽  
pp. 396-402
Author(s):  
Ming June Tsai ◽  
Ching Tsai Wu
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Cortical Bone ◽  
Maximum Stress ◽  
Alveolar Bone ◽  
Titanium Implant ◽  
Titanium Implants ◽  
Large Area ◽  
Element Analysis ◽  
Titanium Screw

This study aimed to confirm the application of multi-implants for mandibles with a large edentulous area using methods of finite element analysis (FEA). 3D finite element models of mandible with multi-implants were generated form reverse engineering of CT images stored in DICOM format. In the FEA of the implant model, the majority of the stress falls onto neck of the titanium implant and is well-distributed around the cylinder body of screw, resulting in less stress being applied to the cortical bone around titanium screw. Under a continual normal force of 100 N, The maximum stress on the cortical bone was located in the area around the titanium implants, and was 111.62Mpa, while the maximum stress on the titanium implant was located at the neck of the implant, and was 120.35 Mpa, much lower than the yield strength of the titanium framework (1260Mpa). The maximum deformation was around 0.65 mm. The deformation of the alveolar bone in our multi-implant model was within the acceptable range. This study show that the titanium screw used for multi-implants meets the requirements in term of physical properties for a large area of defects.

Bionic design of the tower for wind turbine

2021 ◽  
pp. 095440622110046
Author(s):  
Yuqiao Zheng ◽  
Fugang Dong ◽  
Huquan Guo ◽  
Bingxi Lu ◽  
Zhengwen He
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Maximum Stress ◽  
Natural Frequencies ◽  
Bionic Design ◽  
Analytic Hierarchy ◽  
Element Analysis ◽  
Maximum Deformation ◽  
Overall Stability ◽  
Biological Selection

The study obtains a methodology for the bionic design of the tower for wind turbines. To verify the rationality of the biological selection, the Analytic Hierarchy Procedure (AHP) is applied to calculate the similarity between the bamboo and the tower. Creatively, a bionic bamboo tower (BBT) is presented, which is equipped with four reinforcement ribs and five flanges. Further, finite element analysis is employed to comparatively investigate the performance of the BBT and the original tower (OT) in the static and dynamic. Through the investigation, it is suggested that the maximum deformation and maximum stress can be reduced by 5.93 and 13.75% of the BBT. Moreover, this approach results in 3% and 1.1% increase respectively in the First two natural frequencies and overall stability.

Elastic Thermal Stresses in Bimetallic Pipe Welds

1980 ◽  
Vol 102 (4) ◽  
pp. 430-432 ◽  
Author(s):  
R. D. Blevins
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Stress Intensity ◽  
Maximum Stress ◽  
Thermal Stresses ◽  
Simple Expression ◽  
Element Analysis ◽  
Maximum Stress Intensity ◽  
Bimetallic Pipe ◽  
Uniform Change

The elastic thermal stresses in a welded transition between two pipes of the same size but different alloys are explored. A stress-free temperature is postulated and the stress due to a uniform change in temperature is characterized by the maximum stress intensity in the weld. A simple expression for predicting this maximum stress intensity is developed based on the results of finite element analysis.

scholarly journals Influence of fibromucosa height and loading on the stress distribution of a total prosthesis: a finite element analysis

2021 ◽  
Vol 24 (2) ◽  
Author(s):  
Tarcisio José de Arruda Paes Junior ◽  
João Paulo Mendes Tribst ◽  
Amanda Maria de Oliveira Dal Piva ◽  
Viviane Maria Gonçalves de Figueiredo ◽  
Alexandre Luiz Souto Borges ◽  
...  
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Stress Distribution ◽  
Cortical Bone ◽  
Principal Stress ◽  
Maximum Principal Stress ◽  
Element Analysis ◽  
Total Displacement ◽  
Anterior Guidance ◽  
Mandibular Movements

Purpose: To evaluate the effect of fibromucosa height on the stress distribution and displacement of mandibular total prostheses during posterior unilateral load, posterior bilateral load and anterior guidance using the finite element analysis (FEA). Material and methods: 3D virtual models were made to simulate the stress generated during different mandibular movements in a total prosthesis. The contacts were simulated according to the physiology, being considered perfectly bonded between cortical and medullar bones; and between cortical bone and mucosa. Non-linear frictional contact was used for the total prosthesis base and fibromucosa, allowing the prosthesis to slide over the tissue. The cortical bone base was fixed and the 100 N load was applied as unilateral load, posterior bilateral load and anterior guidance simulation. The required results were for maximum principal stress (MPa), microstrain (mm/mm) and total displacement (mm). The numerical results were converted into colorimetric maps and arranged according to corresponding scales. Results: The stress generated in all situations was directly proportional to the fibromucosa height. The maximum principal stress results demonstrated greater magnitude for anterior guidance, posterior unilateral and posterior bilateral, respectively. Only posterior unilateral load demonstrated an increase in bone microstrain, regardless of the fibromucosa height. Prosthesis displacement was lower under posterior bilateral loading. Conclusion: Posterior bilateral loading is indicated for total prosthesis because it allows lower prosthesis displacement, lower stress concentration at the base of the prosthesis and less bone microstrain.   Keywords Finite element analysis; Occlusion; Total prosthesis.

scholarly journals Finite Element Analysis of Needle Insertion Angle in Insulin Therapy

2019 ◽  
Vol 16 (4) ◽  
pp. 7512-7523
Author(s):  
Syakirah Mohamed Amin ◽  
Muhammad Hanif Ramlee ◽  
Hadafi Fitri Mohd Latip ◽  
Gan Hong Seng ◽  
Mohammed Rafiq Abdul Kadir
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Insulin Therapy ◽  
Maximum Stress ◽  
Three Dimensional ◽  
Needle Insertion ◽  
Stress And Strain ◽  
Medical Doctors ◽  
Element Analysis ◽  
Biomechanical Evaluation

Millions in the world suffering diabetes mellitus depends on insulin therapy to control their blood glucose level daily. However, the painful daily injections they need to take could lead to other complications if it is not done correctly. To date, it is suggested by many researchers and medical doctors that the needles should be inserted at any angles of 90º or 45º. Nevertheless, this recommendation has not been supported by clinical or biomechanical evaluation. Hence, this study evaluates the needle insertion for insulin therapy to find the favourable angles in order to reduce injury and pain onto the skin. Finite element analysis was done by  simulating the injection of three-dimensional (3D) needle model into a 3D skin model. The insertions were simulated at two different angles, which are 45ºand 90º with two different lengths of needles; 4 mm and 6 mm. This study concluded the favourable angle for 4 mm needle to be 90º while 6 mm needle was best to be inserted at 45º as these angles exerted the least maximum stress and strain onto the skin.

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