scholarly journals Virtual Structural Analysis of Tibial Fracture Healing from Low-Dose Clinical CT Scans

2018 ◽  
Author(s):  
Peter Schwarzenberg ◽  
Hannah L. Dailey
Keyword(s):  
Structural Analysis ◽  
Fracture Healing ◽  
Bone Healing ◽  
Structural Integrity ◽  
Torsional Rigidity ◽  
Torsion Test ◽  
Ct Scans ◽  
Orthopaedic Trauma ◽  
Element Analysis ◽  
Trauma Research

Quantitative assessment of bone fracture healing remains a significant challenge in orthopaedic trauma research. Accordingly, we developed a new technique for assessing bone healing using virtual mechano-structural analysis of computed tomography (CT) scans. CT scans from 19 fractured human tibiae at 12 weeks after surgery were segmented and prepared for finite element analysis (FEA). Boundary conditions were applied to the models to simulate a torsion test that is commonly used to access the structural integrity of long bones in animal models of fracture healing. The output of each model was the virtual torsional rigidity (VTR) of the healing zone, normalized to the torsional rigidity of each patient’s virtually reconstructed tibia. This provided a structural measure to track the percentage of healing each patient had undergone. Callus morphometric measurements were also collected from the CT scans. Results showed that at 12 weeks post-op, more than 75% of patients achieved a normalized VTR (torsional rigidity relative to uninjured bone) of 85% or above. The predicted intact torsional rigidities compared well with published cadaveric data. Across all patients, callus volume and density were weakly and non-significantly correlated with normalized VTR and time to clinical union. Conversely, normalized VTR was significantly correlated with time to union (R2 = 0.383, p = 0.005). This suggests that fracture scoring methods based on the visual appearance of callus may not accurately predict mechanical integrity. The image-based structural analysis presented here may be a useful technique for assessment of bone healing in orthopaedic trauma research.

scholarly journals An Improved Methodology to Evaluate Cell and Molecular Signals in the Reparative Callus During Fracture Healing

2020 ◽  
Vol 68 (3) ◽  
pp. 199-208
Author(s):  
Anuradha Valiya Kambrath ◽  
Justin N. Williams ◽  
Uma Sankar
Keyword(s):  
Fracture Healing ◽  
Bone Healing ◽  
High Throughput Screening ◽  
Molecular Mechanisms ◽  
Structural Integrity ◽  
Bone Fractures ◽  
Early Stage ◽  
Antigen Retrieval ◽  
Sample Collection ◽  
Immunofluorescence Labeling

Approximately 5% to 10% of all bone fractures do not heal completely, contributing to significant patient suffering and medical costs. Even in healthy individuals, fracture healing is associated with significant downtime and loss of productivity. However, no pharmacological treatments are currently available to promote efficient bone healing. A better understanding of the underlying molecular mechanisms is crucial for developing novel therapies to hasten healing. The early reparative callus that forms around the site of bone injury is a fragile tissue consisting of shifting cell populations held together by loose connective tissue. The delicate callus is challenging to section and is vulnerable to disintegration during the harsh steps of immunostaining, namely, decalcification, deparaffinization, and antigen retrieval. Here, we describe an improved methodology for processing early-stage fracture calluses and immunofluorescence labeling of the sections to visualize the temporal (timing) and spatial (location) patterns of cellular and molecular events that regulate bone healing. This method has a short turnaround time from sample collection to microscopy as it does not require lengthy decalcification. It preserves the structural integrity of the fragile callus as the method does not entail deparaffinization or harsh methods of antigen retrieval. Our method can be adapted for high-throughput screening of drugs that promote efficacious bone healing:

Structural Analysis for a Panamax Bulk Carrier

2008 ◽  
Author(s):  
Sandita Pacuraru-Popoiu ◽  
Paulina Iancu ◽  
Liviu I. Crudu
Keyword(s):  
Structural Analysis ◽  
Stress Distribution ◽  
Structural Integrity ◽  
Dynamic Pressure ◽  
Uniform Structure ◽  
Bulk Carrier ◽  
Element Analysis ◽  
Hull Girder ◽  
Fine Mesh ◽  
Hull Structure

This paper is devoted to the development of a structural analysis for a bulk carrier vessel. According to the CSR requirements for bulk carriers, an assessment of the hull structure using FEA (Finite Element Analysis) on a model extended over 3 cargo holds is presented. This method is used in order to assess the structural integrity of the cargo holds under the considered loads. The selected vessel is a PANAMAX bulk carrier with double hull and longitudinal uniform structure. There are three main priorities for the FE-analysis: one is to perform a fine mesh necessary to capture the stressed induced by the considered loads. The second priority is to apply the right boundary conditions in order to approach the hull girder bending and stress distribution on the cargo holds. The stress distribution is induced by the cargo weight, the hydrostatic pressure and the external water considered as dynamic pressure. The dynamic pressure was computed using an in-house code, neglecting the inertia forces induced by the ship motions and the horizontal accelerations. Also shear forces and bending moments were obtained for head angles of 0, 45 and 180 degrees.

scholarly journals Virtual Mechanical Testing from Low-Dose CT Scans Predicts Tibial Fracture Time to Union and Outperforms Subjective Outcomes Scoring

2018 ◽  
Author(s):  
Peter Schwarzenberg ◽  
Hannah L. Dailey
Keyword(s):  
Mechanical Testing ◽  
Bone Healing ◽  
Low Dose ◽  
Tibial Fracture ◽  
Torsional Rigidity ◽  
Ct Scans ◽  
Patient Specific ◽  
Tibial Shaft Fracture ◽  
Low Dose Ct ◽  
Patient Reported

Background: Quantitative outcomes assessment remains a persistent challenge in orthopaedic trauma. Although patient-reported outcomes measures (PROMs) and radiographic assessments such as RUST scores are frequently used, very little evidence has been presented to support their validity for measuring structural bone formation or biomechanical integrity.Methods: A sequential cohort of tibial shaft fracture patients was prospectively recruited for observation following standard reamed intramedullary nailing in a Level I trauma center. Follow-ups at 6, 12, 18, and 24 weeks included X-rays and completion of PROMs (EQ-5D and pain scores). Low-dose computed-tomography (CT) scans were also completed at 12 weeks. Scans were reconstructed in 3D and subjected to virtual mechanical testing via the finite element method to assess fracture limb torsional rigidity relative to intact bone.Results: Patients reported progressive longitudinal improvement in mobility, self-care, activity, and health over time, but the PROMs were not correlated with structural bone healing. RUST scoring showed moderate intra-rater agreement (ICC = 0.727), but the scores at 12 weeks were not correlated with time to union (R2 = 0.103, p = 0.193) and were only moderately correlated with callus structural integrity (R2 = 0.346, p = 0.010). In contrast, patient-specific virtual torsional rigidity (VTR) was significantly correlated with time to union (R2 = 0.383, p = 0.005) and clearly differentiated one case of delayed union (VTR = 10%, union at 8 months) from the rest of the normally healing cohort (VTR > 60%, median union time 19 weeks) using CT data alone.Conclusions: PROMs provide insight into the natural history of the patient experience after tibial fracture, but have limited utility as a measure of structural bone healing. RUST scoring, although repeatable, is not a valid longitudinal predictor of time to union. In contrast, virtual mechanical testing from low-dose CT scans provides a quantitative and objective structural callus assessment that reliably predicts time to union and may enable early diagnosis of compromised healing.Level of Evidence: Diagnostic Level II.

scholarly journals Pilot study of micromotion nailing for mechanical stimulation of tibial fracture healing

2021 ◽  
Vol 2 (10) ◽  
pp. 825-833
Author(s):  
Hannah L. Dailey ◽  
Peter Schwarzenberg ◽  
Edmund B. Webb, III ◽  
Sinead A. M. Boran ◽  
Shane Guerin ◽  
...  
Keyword(s):  
Pilot Study ◽  
Fracture Healing ◽  
Bone Healing ◽  
Injury Risk ◽  
Group Versus ◽  
Standard Of Care ◽  
Trauma Centre ◽  
Ct Scans ◽  
Control Group ◽  
Study Objective

Aims The study objective was to prospectively assess clinical outcomes for a pilot cohort of tibial shaft fractures treated with a new tibial nailing system that produces controlled axial interfragmentary micromotion. The hypothesis was that axial micromotion enhances fracture healing compared to static interlocking. Methods Patients were treated in a single level I trauma centre over a 2.5-year period. Group allocation was not randomized; both the micromotion nail and standard-of-care static locking nails (control group) were commercially available and selected at the discretion of the treating surgeons. Injury risk levels were quantified using the Nonunion Risk Determination (NURD) score. Radiological healing was assessed until 24 weeks or clinical union. Low-dose CT scans were acquired at 12 weeks and virtual mechanical testing was performed to objectively assess structural bone healing. Results A total of 37 micromotion patients and 46 control patients were evaluated. There were no significant differences between groups in terms of age, sex, the proportion of open fractures, or NURD score. There were no nonunions (0%) in the micromotion group versus five (11%) in the control group. The proportion of fractures united was significantly higher in the micromotion group compared to control at 12 weeks (54% vs 30% united; p = 0.043), 18 weeks (81% vs 59%; p = 0.034), and 24 weeks (97% vs 74%; p = 0.005). Structural bone healing scores as assessed by CT scans tended to be higher with micromotion compared to control and this difference reached significance in patients who had biological comorbidities such as smoking. Conclusion In this pilot study, micromotion fixation was associated with improved healing compared to standard tibial nailing. Further prospective clinical studies will be needed to assess the strength and generalizability of any potential benefits of micromotion fixation. Cite this article: Bone Jt Open 2021;2(10):825–833.

Computation of dimensional variations on the structural analysis of multi-cell aircraft box beams with python scripting

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Hande Yavuz
Keyword(s):  
Structural Analysis ◽  
Shear Flow ◽  
Structural Integrity ◽  
Flow Distribution ◽  
Element Analysis ◽  
Content Type ◽  
Box Beam ◽  
Python Scripting ◽  
Box Beams ◽  
Practical Tool

Purpose Python codes are developed for the versatile structural analysis on a 3 spar multi-cell box beam by means of idealization approach. Design/methodology/approach Shear flow distribution, stiffener loads, location of shear center and location of geometric center are computed via numpy module. Data visualization is performed by using Matplotlib module. Findings Python scripts are developed for the structural analysis of multi-cell box beams in lieu of long hand solutions. In-house developed python codes are made available to be used with finite element analysis for verification purposes. Originality/value The use of python scripts for the structural analysis provides prompt visualization, especially once dimensional variations are concerned in the frame of aircraft structural design. The developed python scripts would serve as a practical tool that is widely applicable to various multi-cell wing boxes for stiffness purposes. This would be further extended to the structural integrity problems to cover the effect of gaps and/or cut-outs in shear flow distribution in box-beams.

Development of a Pile Mooring System for Large Scale FSRUs

2020 ◽  
Author(s):  
Taeyoon Park ◽  
Junhwan Jeon ◽  
Jung Kim ◽  
Sangbae Jeon ◽  
Bongjae Kim ◽  
...  
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Structural Analysis ◽  
Pile Foundation ◽  
Large Scale ◽  
Structural Integrity ◽  
Mooring System ◽  
Basic Design ◽  
Element Analysis ◽  
Pile Resistance

Abstract In this paper, a pile mooring system is introduced as an alternative mooring solution for FSRU. Also, the methodologies of mooring analysis and structural analysis to verify a design of pile mooring system are introduced. The mooring performance of pile mooring system can be assessed by coupled mooring analysis considering stiffness of pile, resistance of soil and hull interface mechanism. The structural integrity of pile, foundation and hull interface can be assessed by non-linear contact finite element analysis. Using these methods, the basic design of pile mooring system for 160,000-CBM large scale FSRU is developed considering practical environmental conditions.

scholarly journals Virtual structural analysis of tibial fracture healing from low-dose clinical CT scans

2019 ◽  
Vol 83 ◽  
pp. 49-56 ◽  
Author(s):  
Peter Schwarzenberg ◽  
Michael M. Maher ◽  
James A. Harty ◽  
Hannah L. Dailey
Keyword(s):  
Structural Analysis ◽  
Fracture Healing ◽  
Low Dose ◽  
Tibial Fracture ◽  
Ct Scans

Tire Bead Overheating in Urban Buses and Trucks Using Drum Brake Systems

1998 ◽  
Vol 26 (1) ◽  
pp. 51-62
Author(s):  
A. L. A. Costa ◽  
M. Natalini ◽  
M. F. Inglese ◽  
O. A. M. Xavier
Keyword(s):  
Heat Transfer ◽  
Finite Element Analysis ◽  
Finite Element ◽  
Thermal Energy ◽  
Structural Integrity ◽  
Experimental Temperature ◽  
Temperature Profiles ◽  
Element Analysis ◽  
Drum Brake ◽  
Fea Model

Abstract Because the structural integrity of brake systems and tires can be related to the temperature, this work proposes a transient heat transfer finite element analysis (FEA) model to study the overheating in drum brake systems used in trucks and urban buses. To understand the mechanics of overheating, some constructive variants have been modeled regarding the assemblage: brake, rims, and tires. The model simultaneously studies the thermal energy generated by brakes and tires and how the heat is transferred and dissipated by conduction, convection, and radiation. The simulated FEA data and the experimental temperature profiles measured with thermocouples have been compared giving good correlation.

scholarly journals Potential and limitations of finite element modelling in assessing structural integrity of coralline algae under future global change

2015 ◽  
Vol 12 (19) ◽  
pp. 5871-5883 ◽  
Author(s):  
L. A. Melbourne ◽  
J. Griffin ◽  
D. N. Schmidt ◽  
E. J. Rayfield
Keyword(s):  
Climate Change ◽  
Finite Element ◽  
Structural Integrity ◽  
Geometric Model ◽  
Algal Growth ◽  
Coralline Algae ◽  
Rocky Shores ◽  
Element Analysis ◽  
Scan Data ◽  
The Impact

Abstract. Coralline algae are important habitat formers found on all rocky shores. While the impact of future ocean acidification on the physiological performance of the species has been well studied, little research has focused on potential changes in structural integrity in response to climate change. A previous study using 2-D Finite Element Analysis (FEA) suggested increased vulnerability to fracture (by wave action or boring) in algae grown under high CO2 conditions. To assess how realistically 2-D simplified models represent structural performance, a series of increasingly biologically accurate 3-D FE models that represent different aspects of coralline algal growth were developed. Simplified geometric 3-D models of the genus Lithothamnion were compared to models created from computed tomography (CT) scan data of the same genus. The biologically accurate model and the simplified geometric model representing individual cells had similar average stresses and stress distributions, emphasising the importance of the cell walls in dissipating the stress throughout the structure. In contrast models without the accurate representation of the cell geometry resulted in larger stress and strain results. Our more complex 3-D model reiterated the potential of climate change to diminish the structural integrity of the organism. This suggests that under future environmental conditions the weakening of the coralline algal skeleton along with increased external pressures (wave and bioerosion) may negatively influence the ability for coralline algae to maintain a habitat able to sustain high levels of biodiversity.

scholarly journals OP0244 A PRECLINICAL TESTING TOOL: THE IN VITRO 3D FRACTURE GAP MODEL

2020 ◽  
Vol 79 (Suppl 1) ◽  
pp. 154.1-154
Author(s):  
M. Pfeiffenberger ◽  
A. Damerau ◽  
P. Hoff ◽  
A. Lang ◽  
F. Buttgereit ◽  
...  
Keyword(s):  
Fracture Healing ◽  
Bone Healing ◽  
Inflammatory Markers ◽  
Initial Phase ◽  
Gap Model ◽  
Osteogenic Markers ◽  
Immunosuppressed Patients ◽  
The Impact

Background:Approximately 10% of fractures lead to significant fracture healing disorders, with a tendency to further increase due to the aging population. Of note, especially immunosuppressed patients with ongoing inflammation show difficulties in the correct course of fracture healing leading to fracture healing disorders. Most notably, invading immune cells and secreted cytokines are considered to provide an inflammatory microenvironment within the fracture gap, primarily during the initial phase of fracture healing. Current research has the focus on small animal models, facing the problem of translation towards the human system. In order to improve the therapy of fracture healing disorders, we have developed a human cell-basedin vitromodel to mimic the initial phase of fracture healing adequately. This model will be used for the development of new therapeutic strategies.Objectives:Our aim is to develop anin vitro3D fracture gap model (FG model) which mimics thein vivosituation in order to provide a reliable preclinical test system for fracture healing disorders.Methods:To assemble our FG model, we co-cultivated coagulated peripheral blood and primary human mesenchymal stromal cells (MSCs) mimicking the fracture hematoma (FH model) together with a scaffold-free bone-like construct mimicking the bony part of the fracture gap for 48 h under hypoxic conditions (n=3), in order to reflect thein vivosituation after fracture most adequately. To analyze the impact of the bone-like construct on thein vitroFH model with regard to its osteogenic induction capacity, we cultivated the fracture gap models in either medium with or without osteogenic supplements. To analyze the impact of Deferoxamine (DFO, known to foster fracture healing) on the FG model, we further treated our FG models with either 250 µmol DFO or left them untreated. After incubation and subsequent preparation of the fracture hematomas, we evaluated gene expression of osteogenic (RUNX2,SPP1), angiogenic (VEGF,IL8), inflammatory markers (IL6,IL8) and markers for the adaptation towards hypoxia (LDHA,PGK1) as well as secretion of cytokines/chemokines using quantitative PCR and multiplex suspension assay, respectively.Results:We found via histology that both the fracture hematoma model and the bone-like construct had close contact during the incubation, allowing the cells to interact with each other through direct cell-cell contact, signal molecules or metabolites. Additionally, we could show that the bone-like constructs induced the upregulation of osteogenic markers (RUNX2, SPP1) within the FH models irrespective of the supplementation of osteogenic supplements. Furthermore, we observed an upregulation of hypoxia-related, angiogenic and osteogenic markers (RUNX2,SPP1) under the influence of DFO, and the downregulation of inflammatory markers (IL6,IL8) as compared to the untreated control. The latter was also confirmed on protein level (e.g. IL-6 and IL-8). Within the bone-like constructs, we observed an upregulation of angiogenic markers (RNA-expression ofVEGF,IL8), even more pronounced under the treatment of DFO.Conclusion:In summary, our findings demonstrate that our establishedin vitroFG model provides all osteogenic cues to induce the initial bone healing process, which could be enhanced by the fracture-healing promoting substance DFO. Therefore, we conclude that our model is indeed able to mimic correctly the human fracture gap situation and is therefore suitable to study the influence and efficacy of potential therapeutics for the treatment of bone healing disorders in immunosuppressed patients with ongoing inflammation.Disclosure of Interests:Moritz Pfeiffenberger: None declared, Alexandra Damerau: None declared, Paula Hoff: None declared, Annemarie Lang: None declared, Frank Buttgereit Grant/research support from: Amgen, BMS, Celgene, Generic Assays, GSK, Hexal, Horizon, Lilly, medac, Mundipharma, Novartis, Pfizer, Roche, and Sanofi., Timo Gaber: None declared

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