Computational Modeling of the Patient-Specific Femoral Head before and after the Treatment

2014 ◽  
Vol 998-999 ◽  
pp. 214-218
Author(s):  
Yu Qian Mei ◽  
Chao Lu ◽  
Hai Jun He ◽  
Wei Heng Chen ◽  
Duan Duan Chen
Keyword(s):  
Femoral Head ◽  
Drug Treatment ◽  
Cancellous Bone ◽  
Equivalent Stress ◽  
Three Dimensional ◽  
Femoral Head Necrosis ◽  
Patient Specific ◽  
Before And After ◽  
Cortical Shell ◽  
Three Dimensional Models

In femoral head necrosis, the cortical shell of the femoral head collapses and buckles into the cancellous bone. The purpose of this study is to explore the biomechanical characteristics of the femoral head and the necrosis region by comparing the results before and after drug treatment. In this paper, we study two patient cases with femoral head necrosis disease and establish the corresponding computational three-dimensional models. The results show that the deformation of the femur decreases slightly after the treatment, the equivalent stress distributes more evenly, and the stress magnitude reduces. The results also reveal that the volume of the necrosis in the femoral head decreases after treatment, the overall necrosis presents relatively lower equivalent stress, and the area with the relatively high equivalent stress is smaller comparing to the necrosis in femoral head before treatment.

scholarly journals Anxiety reduction after pre-procedure meetings in patients with CHD

2020 ◽  
Vol 30 (7) ◽  
pp. 991-994 ◽  
Author(s):  
Preston J. Boyer ◽  
Joshua A. Yell ◽  
Jennifer G. Andrews ◽  
Michael D. Seckeler
Keyword(s):  
Trait Anxiety ◽  
Three Dimensional ◽  
Anxiety Reduction ◽  
Patient Specific ◽  
State Trait Anxiety Inventory ◽  
Educational Tools ◽  
Complex Anatomy ◽  
Before And After ◽  
Cardiac Models ◽  
Three Dimensional Models

AbstractBackground:Cardiac catheterisations for CHD produce anxiety for patients and families. Current strategies to mitigate anxiety and explain complex anatomy include pre-procedure meetings and educational tools (cardiac diagrams, echocardiograms, imaging, and angiography). More recently, three-dimensionally printed patient-specific models can be added to the armamentarium. The purpose of this study was to evaluate the efficacy of pre-procedure meetings and of different educational tools to reduce patient and parent anxiety before a catheterisation.Methods:Prospective study of patients ≥18 and parents of patients <18 scheduled for clinically indicated catheterisations. Patients completed online surveys before and after meeting with the interventional cardiologist, who was blinded to study participation. Both the pre- and post-meeting surveys measured anxiety using the State-Trait Anxiety Inventory. In addition, the post-meeting survey evaluated the subjective value (from 1 to 4) of individual educational tools: physician discussion, cardiac diagrams, echocardiograms, prior imaging, angiograms and three-dimensionally printed cardiac models. Data were compared using paired t-tests.Results:Twenty-three patients consented to participate, 16 had complete data for evaluation. Mean State-Trait Anxiety Inventory scores were abnormally elevated at baseline and decreased into the normal range after the pre-procedure meeting (39.8 versus 31, p = 0.008). Physician discussion, angiograms, and three-dimensional models were reported to be most effective at increasing understanding and reducing anxiety.Conclusion:In this pilot study, we have found that pre-catheterisation meetings produce a measurable decrease in patient and family anxiety before a procedure. Discussions of the procedure, angiograms, and three-dimensionally printed cardiac models were the most effective educational tools.

Prediction of Femoral Head Collapse in Osteonecrosis

2005 ◽  
Vol 128 (3) ◽  
pp. 467-470 ◽  
Author(s):  
K. Y. Volokh ◽  
H. Yoshida ◽  
A. Leali ◽  
J. F. Fetto ◽  
E. Y. S. Chao
Keyword(s):  
Femoral Head ◽  
Contact Problem ◽  
Contact Pressure ◽  
Cancellous Bone ◽  
Local Buckling ◽  
Young Modulus ◽  
Head Model ◽  
Element Mesh ◽  
Femoral Head Collapse ◽  
Cortical Shell

The femoral head deteriorates in osteonecrosis. As a consequence of that, the cortical shell of the femoral head can buckle into the cancellous bone supporting it. In order to examine the buckling scenario we performed numerical analysis of a realistic femoral head model. The analysis included a solution of the hip contact problem, which provided the contact pressure distribution, and subsequent buckling simulation based on the given contact pressure. The contact problem was solved iteratively by approximating the cartilage by a discrete set of unilateral linear springs. The buckling calculations were based on a finite element mesh with brick elements for the cancellous bone and shell elements for the cortical shell. Results of 144 simulations for a variety of geometrical, material, and loading parameters strengthen the buckling scenario. They, particularly, show that the normal cancellous bone serves as a strong supporting foundation for the cortical shell and prevents it from buckling. However, under the development of osteonecrosis the deteriorating cancellous bone is unable to prevent the cortical shell from buckling and the critical pressure decreases with the decreasing Young modulus of the cancellous bone. The local buckling of the cortical shell seems to be the driving force of the progressive fracturing of the femoral head leading to its entire collapse. The buckling analysis provides an additional criterion of the femoral head collapse, the critical contact pressure. The buckling scenario also suggests a new argument in speculating on the femoral head reinforcement. If the entire collapse of the femoral head starts with the buckling of the cortical shell then it is reasonable to place the reinforcement as close to the cortical shell as possible.

scholarly journals The correlation between the teardrop angle and anterior lunate facet displacement in plating distal radial fractures

2019 ◽  
Vol 44 (5) ◽  
pp. 462-467 ◽  
Author(s):  
Teun Teunis ◽  
Sjoerd Meijer ◽  
Jesse Jupiter ◽  
Daniel Rikli ◽  
Keyword(s):  
Computed Tomography ◽  
Surface Area ◽  
Plate Fixation ◽  
Three Dimensional ◽  
Anterior Plate ◽  
Distal Radial Fractures ◽  
Computed Tomography Scans ◽  
Before And After ◽  
Anterior Plating ◽  
Three Dimensional Models

This study aimed to determine the association of teardrop angle and anteroposterior distance with anterior lunate facet displacement and articular congruity before and after anterior plating of distal radial fractures. We included 36 patients with complete intra-articular distal radial fractures with separate anterior lunate facet fragments. On radiographs we determined the teardrop angle and anteroposterior distance. On digital three-dimensional models we measured proximal-distal, anteroposterior and ulnoradial anterior lunate facet displacement, and we outlined the gap surface area. Preoperatively, teardrop angle was highly associated with the extent of anterior lunate facet displacement. Increased anteroposterior distance was mainly associated with articular incongruity after anterior plate fixation. This information may reduce the need of preoperative computed tomography scans in fractures with a normal tear drop angle. This is particularly useful in low-resource settings.

Study on Precision Forging Schemes of Hypoid Driving Gear

2012 ◽  
Vol 472-475 ◽  
pp. 692-695
Author(s):  
Jian Hua Wang ◽  
Fu Xiao Chen
Keyword(s):  
Equivalent Stress ◽  
Three Dimensional ◽  
Equivalent Strain ◽  
Precision Forging ◽  
Forming Technology ◽  
Blank Shape ◽  
Simulation Results ◽  
Three Dimensional Models ◽  
3D Software ◽  
Deform 3D

By analyzing the characteristics and forming technology of hypoid driving gear, it was suitable for adopting fully enclosed die forging principle to form the gear. Based on different forging methods, three kinds of blank shape and corresponding forming schemes were designed. The three dimensional models of blank and die were created by the UG software. The three forming schemes were simulated by the Deform-3D software. The simulation results of distribution of equivalent stress, distribution of equivalent strain and load-stroke curve were comparatively analyzed. Then the most reasonable scheme was chosen. At last, the rationality of numerical simulation can be further verified by the optimized scheme was proved by experiment.

scholarly journals Mechanical Evaluation of Collapse Risk for Osteonecrosis of Femoral Head Post-Medical Treatment

2021 ◽  
Author(s):  
Yuqian Mei ◽  
Qi Tang ◽  
Songhao Chen ◽  
Duanduan Chen
Keyword(s):  
Femoral Head ◽  
Medical Treatment ◽  
Early Stage ◽  
Equivalent Stress ◽  
Stress Index ◽  
Patient Specific ◽  
Relative Stress ◽  
The Mean ◽  
One Year

Abstract Background: Early-stage osteonecrosis of the femoral head can progressively induce the bone collapse and the accuracy of the collapse risk evaluation is limited. This study aims to propose a potential collapse indicator by biomechanical evaluating the treatment effectiveness. Methods: Six patient-specific models pre- (initial presentation) and post- medical treatment were established and elastic properties of the bone were assigned with a function of spatial-variant Hounsfield unit values. Morphological and mechanical analyses were compared between pre- and post-treatment models. Results: In the morphological study, four cases show the reduced ratio of low-density necrotic volume, but not consistent with one-year follow-up results. In the mechanical analysis, the equivalent stress variation near the Ward triangle shows consistency in the one-year outcome. Moreover, a parameter - relative stress index, the ratio between the mean volume stress index and the mean volume equivalent stress, is proposed. A smaller value of the relative stress index indicates stronger bone compressive strength and its variation is consistent with the follow-up results. Conclusions: Results implicate that to evaluate the effectiveness of medical treatments, the morphologic analysis should be considered but the mechanical capability and the loading transfer path through the necrotic and viable bone play a more important role.

Estimation of [177Lu]PSMA-617 tumor uptake based on voxel-wise 3D Monte Carlo tumor dosimetry in patients with metastasized castration resistant prostate cancer

2020 ◽  
Vol 59 (05) ◽  
pp. 365-374
Author(s):  
Theresa Ida Götz ◽  
Elmar Wolfgang Lang ◽  
Olaf Prante ◽  
Michael Cordes ◽  
Torsten Kuwert ◽  
...  
Keyword(s):  
Prostate Cancer ◽  
Monte Carlo ◽  
Three Dimensional ◽  
Absorbed Dose ◽  
Whole Body ◽  
Patient Specific ◽  
Average Dose ◽  
Castration Resistant Prostate Cancer ◽  
Castration Resistant ◽  
Before And After

Abstract Objective Patients with advanced prostate cancer are suitable candidates for [177Lu]PSMA-617 therapy. Integrated SPECT/CT systems have the potential to improve the accuracy of patient-specific tumor dosimetry. We present a novel patient-specific Monte Carlo based voxel-wise dosimetry approach to determine organ and total tumor doses (TTD). Methods 13 patients with histologically confirmed metastasized castration-resistant prostate cancer were treated with a total of 18 cycles of [177Lu]PSMA-617 therapy. In each patient, dosimetry was performed after the first cycle of [177Lu]PSMA-617 therapy. Regions of interest were defined manually on the SPECT/CT images for the kidneys, spleen and all 295 PSMA-positive tumor lesions in the field of view. The absorbed dose to normal organs and to all tumor lesions were calculated by a three dimensional dosimetry method based on Monte Carlo Simulations. Results The average dose values yielded the following results: 2.59 ± 0.63 Gy (1.67–3.92 Gy) for the kidneys, 0.79 ± 0.46 Gy (0.31–1.90 Gy) for the spleen and 11.00 ± 11.97 Gy (1.28–49.10 Gy) for all tracer-positive tumor lesions. A trend towards higher TTD was observed in patients with Gleason Scores > 8 compared to Gleason Scores ≤ 8 and in lymph node metastases compared to bone metastases. A significant correlation was determined between the serum-PSA level before RLT and the TTD (r = –0.57, p < 0.05), as well as between the TTD with the percentage change of serum-PSA levels before and after therapy was observed (r = –0.57, p < 0.05). Patients with higher total tumor volumes of PSMA-positive lesions demonstrated significantly lower kidney average dose values (r = –0.58, p < 0.05). Conclusion The presented novel Monte Carlo based voxel-wise dosimetry calculates a patient specific whole-body dose distribution, thus taking into account individual anatomies and tissue compositions showing promising results for the estimation of radiation doses of normal organs and PSMA-positive tumor lesions.

Clinical and laboratory studies of the effectiveness of a non-invasive method of treating caries in the stage of white chalky spot with Icon technology

2021 ◽  
pp. 32-36
Author(s):  
S.U. Maksyukov ◽  
D.V. Yogina ◽  
D.S. Maksyukov
Keyword(s):  
Three Dimensional ◽  
White Spot ◽  
Laboratory Studies ◽  
X Ray ◽  
Non Invasive ◽  
Before And After ◽  
Invasive Method ◽  
Tooth Dentin ◽  
Three Dimensional Models ◽  
Comparison Of The Results

The aim of the study was to evaluate the effectiveness of a non-invasive method of treating caries at the stage of a white chalky spot with the Infiltration Concept (Icon) technology. Materials and methods: the clinical and laboratory study included 5 teeth with caries in the white spot stage, removed according to orthodontic indications. The study included scanning in an X-ray computer microtomograph of selected samples of teeth with caries in the white spot stage before and after treatment of the caries area according to Icon technology. For each sample, 1601 X-ray projections were obtained, which were then reconstructed using the XRM Reconstructor software. The comparison of the mineralization density of the samples was carried out by calibrating the obtained images, reconstructing three-dimensional models of tooth samples and constructing maps of the mineralization fee. Results and conclusions. Data on the mineralization density before and after treatment according to Icon technology were obtained in the following areas of the studied teeth: caries in the white spot stage; dentin bordering on caries (the area touches the dentinoemal border as close as possible to the caries area); the area of healthy enamel on the opposite side of the tooth; dentin bordering on healthy enamel (near the dentinoemal border and as close as possible to the healthy enamel area). A comparison of the results obtained does not allow us to conclude about the effectiveness of treatment according to the Icon technology. Moreover, the mineralization density of the studied areas significantly decreased after the treatment.

Analysis and Optimization of Dismantling Machine Shear Head Based on ANSYS Workbench

2014 ◽  
Vol 945-949 ◽  
pp. 653-657
Author(s):  
Wan Peng Du ◽  
Yong Jian Zhang ◽  
Chen Quan Zhou ◽  
Ai Hui Zhang ◽  
Ji Yu ◽  
...  
Keyword(s):  
Topology Optimization ◽  
Shear Force ◽  
Equivalent Stress ◽  
Three Dimensional ◽  
Total Deformation ◽  
Design Variables ◽  
Maximum Shear Force ◽  
Maximum Equivalent Stress ◽  
Three Dimensional Models ◽  
Ansys Workbench

The object is dismantling machine shear head with 500kN’s maximum shear force. The three-dimensional models, static analysis, topology optimization were done in the ANSYS Workbench. And the goal driven optimization was done which based on topology optimization. The maximum total deformation, maximum equivalent stress and geometry mass were selected as objective parameters and the distance of two connecting holes, diameter of long hole and length of blade as design variables. At last, the optimized structure was checked. The strength and rigidity meet the requirements and the mass decreased.

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