scholarly journals Cortical bone mapping improves finite element strain prediction accuracy at the proximal femur

Bone ◽  
2020 ◽  
Vol 136 ◽  
pp. 115348 ◽  
Author(s):  
Enrico Schileo ◽  
Jonathan Pitocchi ◽  
Cristina Falcinelli ◽  
Fulvia Taddei
Keyword(s):  
Finite Element ◽  
Cortical Bone ◽  
Proximal Femur ◽  
Prediction Accuracy ◽  
Bone Mapping

Individual-specific multi-scale finite element simulation of cortical bone of human proximal femur

2013 ◽  
Vol 244 ◽  
pp. 298-311 ◽  
Author(s):  
Maria-Grazia Ascenzi ◽  
Neal P. Kawas ◽  
Andre Lutz ◽  
Dieter Kardas ◽  
Udo Nackenhorst ◽  
...  
Keyword(s):  
Finite Element ◽  
Finite Element Simulation ◽  
Cortical Bone ◽  
Proximal Femur ◽  
Multi Scale ◽  
Element Simulation

Cortical bone finite element models in the estimation of experimentally measured failure loads in the proximal femur

Bone ◽  
2012 ◽  
Vol 51 (4) ◽  
pp. 737-740 ◽  
Author(s):  
Janne E.M. Koivumäki ◽  
Jérôme Thevenot ◽  
Pasi Pulkkinen ◽  
Volker Kuhn ◽  
Thomas M. Link ◽  
...  
Keyword(s):  
Finite Element ◽  
Cortical Bone ◽  
Proximal Femur ◽  
Finite Element Models ◽  
Failure Loads

Relationships Between Stiffness of Human Distal Tibia, Distal Radius, Proximal Femur, and Vertebral Body Assessed by HR-pQCT and cQCT Based Finite Element Analyses

2009 ◽  
Author(s):  
X. Sherry Liu ◽  
Adi Cohen ◽  
Perry T. Yin ◽  
Joan M. Lappe ◽  
Robert R. Recker ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Mechanical Properties ◽  
Finite Element ◽  
Lumbar Spine ◽  
Fracture Risk ◽  
Cortical Bone ◽  
Bone Strength ◽  
Distal Radius ◽  
Proximal Femur ◽  
Quantitative Computed Tomography

High-resolution peripheral quantitative computed tomography (HR-pQCT) is a promising clinical tool that permits separate measurements of trabecular and cortical bone compartments at the distal radius and tibia. It has an isotropic voxel size of 82 μm, which is high enough to assess the fine microstructural details of trabecular architecture. HR-pQCT images can also be used for building microstructural finite element (μFE) models to estimate the mechanical competence of whole bone segments. Melton et al. showed that derived bone strength parameters (axial rigidity and fall load to failure load ratio) are additional to BMD and bone geometry and microstructure as determinants of forearm fracture risk prediction [1]. Boutroy et al. found that the proportion of the load carried by trabecular bone versus cortical bone is associated with wrist fracture independently of BMD and microarchitecture [2]. These clinical studies demonstrate that HR-pQCT based μFE analyses can provide measurements of mechanical properties that independently associate with fracture risk. However, microstructure of one skeletal site may be different from that of another site. It is unclear whether and to what extent these peripheral measurements reflect the bone strength of the proximal femur and vertebral bodies, the sites of frequent osteoporotic fractures. Currently, central quantitative computed tomography (cQCT) is the most commonly used clinical imaging modality to quantify the structural and mechanical properties of the proximal femur and lumbar spine. We therefore evaluated relationships between the stiffness of the distal radius and tibia estimated by HR-pQCT-based FEA with that of the proximal femur and lumbar spine which was estimated from cQCT-based FEA in the same human subjects.

Fracture Prediction for the Proximal Femur Using Finite Element Models: Part II—Nonlinear Analysis

1991 ◽  
Vol 113 (4) ◽  
pp. 361-365 ◽  
Author(s):  
J. C. Lotz ◽  
E. J. Cheal ◽  
W. C. Hayes
Keyword(s):  
Finite Element ◽  
Trabecular Bone ◽  
Cortical Bone ◽  
Excellent Agreement ◽  
Proximal Femur ◽  
Bone Fracture ◽  
Nonlinear Material ◽  
Finite Element Models ◽  
Model Predictions

In Part I we reported the results of linear finite element models of the proximal femur generated using geometric and constitutive data collected with quantitative computed tomography. These models demonstrated excellent agreement with in vitro studies when used to predict ultimate failure loads. In Part II, we report our extension of those finite element models to include nonlinear behavior of the trabecular and cortical bone. A highly nonlinear material law, originally designed for representing concrete, was used for trabecular bone, while a bilinear material law was used for cortical bone. We found excellent agreement between the model predictions and in vitro fracture data for both the onset of bone yielding and bone fracture. For bone yielding, the model predictions were within 2 percent for a load which simulated one-legged stance and 1 percent for a load which simulated a fall. For bone fracture, the model predictions were within 1 percent and 17 percent, respectively. The models also demonstrated different fracture mechanisms for the two different loading configurations. For one-legged stance, failure within the primary compressive trabeculae at the subcapital region occurred first, leading to load transfer and, ultimately, failure of the surrounding cortical shell. However, for a fall, failure of the cortical and trabecular bone occurred simultaneously within the intertrochanteric region. These results support our previous findings that the strength of the subcapital region is primarily due to trabecular bone whereas the strength of the intertrochanteric region is primarily due to cortical bone.

Novel and simplified optimisation pathway using response surface and design of experiments methodologies for dental implants based on the stress of the cortical bone

2021 ◽  
pp. 095441192110253
Author(s):  
João PO Freitas ◽  
Bruno Agostinho Hernandez ◽  
Paulo J Paupitz Gonçalves ◽  
Edmea C Baptista ◽  
Edson A Capello Sousa
Keyword(s):  
Finite Element ◽  
Stress Distribution ◽  
Design Of Experiments ◽  
Cortical Bone ◽  
Response Surface ◽  
Dental Implants ◽  
Finite Element Models ◽  
Long Term Treatment ◽  
Dimensional Finite Element ◽  
Surrounding Bone

Dental implants are widely used as a long-term treatment solution for missing teeth. A titanium implant is inserted into the jawbone, acting as a replacement for the lost tooth root and can then support a denture, crown or bridge. This allows discreet and high-quality aesthetic and functional improvement, boosting patient confidence. The use of implants also restores normal functions such as speech and mastication. Once an implant is placed, the surrounding bone will fuse to the titanium in a process known as osseointegration. The success of osseointegration is dependent on stress distribution within the surrounding bone and thus implant geometry plays an important role in it. Optimisation analyses are used to identify the geometry which results in the most favourable stress distribution, but the traditional methodology is inefficient, requiring analysis of numerous models and parameter combinations to identify the optimal solution. A proposed improvement to the traditional methodology includes the use of Design of Experiments (DOE) together with Response Surface Methodology (RSM). This would allow for a well-reasoned combination of parameters to be proposed. This study aims to use DOE, RSM and finite element models to develop a simplified optimisation analysis method for dental implant design. Drawing on data and results from previous studies, two-dimensional finite element models of a single Branemark implant, a multi-unit abutment, two prosthetic screws, a prosthetic crown and a region of mandibular bone were built. A small number of combinations of implant diameter and length were set based on the DOE method to analyse the influence of geometry on stress distribution at the bone-implant interface. The results agreed with previous studies and indicated that implant length is the critical parameter in reducing stress on cortical bone. The proposed method represents a more efficient analysis of multiple geometrical combinations with reduced time and computational cost, using fewer than a third of the models required by the traditional methods. Further work should include the application of this methodology to optimisation analyses using three-dimensional finite element models.

scholarly journals Rib Cortical Bone Fracture Risk as a Function of Age and Rib Strain: Updated Injury Prediction Using Finite Element Human Body Models

2021 ◽  
Vol 9 ◽  
Author(s):  
Karl-Johan Larsson ◽  
Amanda Blennow ◽  
Johan Iraeus ◽  
Bengt Pipkorn ◽  
Nils Lubbe
Keyword(s):  
Finite Element ◽  
Fracture Risk ◽  
Cortical Bone ◽  
Failure Strain ◽  
Risk Function ◽  
Rib Fracture ◽  
Probabilistic Framework ◽  
Age Dependent ◽  
Risk Curve ◽  
Human Body Models

To evaluate vehicle occupant injury risk, finite element human body models (HBMs) can be used in vehicle crash simulations. HBMs can predict tissue loading levels, and the risk for fracture can be estimated based on a tissue-based risk curve. A probabilistic framework utilizing an age-adjusted rib strain-based risk function was proposed in 2012. However, the risk function was based on tests from only twelve human subjects. Further, the age adjustment was based on previous literature postulating a 5.1% decrease in failure strain for femur bone material per decade of aging. The primary aim of this study was to develop a new strain-based rib fracture risk function using material test data spanning a wide range of ages. A second aim was to update the probabilistic framework with the new risk function and compare the probabilistic risk predictions from HBM simulations to both previous HBM probabilistic risk predictions and to approximate real-world rib fracture outcomes. Tensile test data of human rib cortical bone from 58 individuals spanning 17–99 years of ages was used. Survival analysis with accelerated failure time was used to model the failure strain and age-dependent decrease for the tissue-based risk function. Stochastic HBM simulations with varied impact conditions and restraint system settings were performed and probabilistic rib fracture risks were calculated. In the resulting fracture risk function, sex was not a significant covariate—but a stronger age-dependent decrease than previously assumed for human rib cortical bone was evident, corresponding to a 12% decrease in failure strain per decade of aging. The main effect of this difference is a lowered risk prediction for younger individuals than that predicted in previous risk functions. For the stochastic analysis, the previous risk curve overestimated the approximate real-world rib fracture risk for 30-year-old occupants; the new risk function reduces the overestimation. Moreover, the new function can be used as a direct replacement of the previous one within the 2012 probabilistic framework.

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 COMPARATIVE ANALYSIS OF MONOCORTICAL AND BICORTICAL METHODS OF INSTALLING MINI-IMPLANTS

2021 ◽  
pp. 38-40
Author(s):  
O.Yu. Rivis ◽  
V.S. Melnyk ◽  
M.V. Rivis ◽  
K.V. Zombor
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Comparative Analysis ◽  
Cortical Bone ◽  
Bone Tissue ◽  
Orthodontic Treatment ◽  
The Finite Element Method ◽  
Force Load ◽  
Mini Implants ◽  
Element Method

The aim of the study. Carry out a comparative analysis of the support ability of human jaw bone tissue in monocortical and bicortical installation of a mini-implant of own design OMG. Research methods. In order to study biomechanical characteristics of developed OMG mini-implant and bone tissue capacity during monocortical and bicortical installation, the finite element method (MSE) was used. The scheme and finite element 2-D model of bicortical installation of OMG mini-implant (length 8 mm, diameter 1.8 mm) provided full penetration through one layer of cortical bone equal to 1 mm, the entire cancellous bone and immersion in the second layer of cortical bone by 0, 5 mm. No implantation was immersed in the second cortical layer of bone during monocortical installation. A single force load of 1 N was applied in the horizontal direction parallel to the cortical plate of the bone. Results of the study. One of the most important factors leading to the success of the use of a mini-implant is its stability in the process of orthodontic treatment. Quite a high level of failure in the monocortical installation of mini-screws has led to the search for better methods to ensure the stability of their use. This was a bicortical method of fixation, based on the placement of the minig screw in the thickness of the two cortical plates of the jaws. Area for such installation of mini-screws can be a site of a palate and alveolar sprouts at installation of miniimplants through all its thickness. As shown by our data on the use of the finite element method under the force load of the biomechanical system "bone - mini-implant", the stress concentration zone is located in the area of the cortical bone of the jaw. The results of the calculation of the maximum stresses (σmax, MPa) and the maximum possible displacements (umax, mm) of the mini-implant in the biomechanical system "bone - mini-implant" in monocortical installation were, respectively, 8.27 MPa and 0.300 * 10-8 mm and in bicortical installation 6.00 MPa and 0.201 * 10-8 mm. The bicortical method of fixing the mini-implant in the jaw bones significantly increases the ability to resist deformation of this type of biomechanical system under force loads of the mini-implant. In the bicortical method of mini-implant placement, the extreme values of equivalent according to Mises stresses in the upper part of the cortical bone of the jaw are reduced by 27%. This can be explained by a significant increase in the area of contact due to the two layers of the cortical bone of the jaw with the surface of the mini-implant. Conclusion. The bicortical method of installing mini-implants is a more effective and reliable way to provide skeletal support during orthodontic treatment.

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