scholarly journals Automated Pipeline to Generate Anatomically Accurate Patient-Specific Biomechanical Models of Healthy and Pathological FSUs

2021 ◽  
Vol 9 ◽  
Author(s):  
Sebastiano Caprara ◽  
Fabio Carrillo ◽  
Jess G. Snedeker ◽  
Mazda Farshad ◽  
Marco Senteler
Keyword(s):  
Finite Element ◽  
Spinal Surgery ◽  
Computational Models ◽  
Lumbar Vertebrae ◽  
Automatic Generation ◽  
Biomechanical Analysis ◽  
Patient Specific ◽  
Clinical Environment ◽  
Biomechanical Models ◽  
Flexion Extension

State-of-the-art preoperative biomechanical analysis for the planning of spinal surgery not only requires the generation of three-dimensional patient-specific models but also the accurate biomechanical representation of vertebral joints. The benefits offered by computational models suitable for such purposes are still outweighed by the time and effort required for their generation, thus compromising their applicability in a clinical environment. In this work, we aim to ease the integration of computerized methods into patient-specific planning of spinal surgery. We present the first pipeline combining deep learning and finite element methods that allows a completely automated model generation of functional spine units (FSUs) of the lumbar spine for patient-specific FE simulations (FEBio). The pipeline consists of three steps: (a) multiclass segmentation of cropped 3D CT images containing lumbar vertebrae using the DenseVNet network, (b) automatic landmark-based mesh fitting of statistical shape models onto 3D semantic segmented meshes of the vertebral models, and (c) automatic generation of patient-specific FE models of lumbar segments for the simulation of flexion-extension, lateral bending, and axial rotation movements. The automatic segmentation of FSUs was evaluated against the gold standard (manual segmentation) using 10-fold cross-validation. The obtained Dice coefficient was 93.7% on average, with a mean surface distance of 0.88 mm and a mean Hausdorff distance of 11.16 mm (N = 150). Automatic generation of finite element models to simulate the range of motion (ROM) was successfully performed for five healthy and five pathological FSUs. The results of the simulations were evaluated against the literature and showed comparable ROMs in both healthy and pathological cases, including the alteration of ROM typically observed in severely degenerated FSUs. The major intent of this work is to automate the creation of anatomically accurate patient-specific models by a single pipeline allowing functional modeling of spinal motion in healthy and pathological FSUs. Our approach reduces manual efforts to a minimum and the execution of the entire pipeline including simulations takes approximately 2 h. The automation, time-efficiency and robustness level of the pipeline represents a first step toward its clinical integration.

scholarly journals Automatic Generation of Personalised Skeletal Models of the Lower Limb from Three-Dimensional Bone Geometries

2020 ◽  
Author(s):  
Luca Modenese ◽  
Jean-Baptiste Renault
Keyword(s):  
Lower Limb ◽  
Subtalar Joint ◽  
Computational Models ◽  
Three Dimensional ◽  
Automatic Generation ◽  
Medical Image Segmentation ◽  
Biomechanical Analysis ◽  
Patient Specific ◽  
Musculoskeletal Models ◽  
Scripting Language

AbstractThe generation of personalised and patient-specific musculoskeletal models is currently a cumbersome and time-consuming task that normally requires several processing hours and trained operators. We believe that this aspect discourages the use of computational models even when appropriate data are available and personalised biomechanical analysis would be beneficial. In this paper we present a computational tool that enables the fully automatic generation of skeletal models of the lower limb from three-dimensional bone geometries, normally obtained by segmentation of medical images. This tool was evaluated against four manually created lower limb models finding remarkable agreement in the computed joint parameters, well within human operator repeatability. The coordinate systems origins were identified with maximum differences between 0.5 mm (hip joint) and 5.9 mm (subtalar joint), while the joint axes presented discrepancies between 1° (knee joint) to 11° (subtalar joint). To prove the robustness of the methodology, the models were built from four datasets including both genders, anatomies ranging from juvenile to elderly and bone geometries reconstructed from high-quality computed tomography as well as lower-quality magnetic resonance imaging scans. The entire workflow, implemented in MATLAB scripting language, executed in seconds and required no operator intervention, creating lower extremity models ready to use for kinematic and kinetic analysis or as baselines for more advanced musculoskeletal modelling approaches, of which we provide some practical examples. We auspicate that this technical advancement, together with upcoming progress in medical image segmentation techniques, will promote the use of personalised models in larger-scale studies than those hitherto undertaken.

AN ALGORITHM TO CALCULATE THE COMPONENTS OF ALL MUSCLE FORCES DURING EACH PHASES OF THE GAIT CYCLE, FOR THE PELVIC-FEMUR COMPLEX

2005 ◽  
Vol 05 (04) ◽  
pp. 539-548 ◽  
Author(s):  
SANTANU MAJUMDER ◽  
AMIT ROYCHOWDHURY ◽  
SUBRATA PAL
Keyword(s):  
Finite Element ◽  
Hip Joint ◽  
Computational Models ◽  
Gait Cycle ◽  
Muscle Force ◽  
Fe Analysis ◽  
Muscle Forces ◽  
Force Magnitude ◽  
Flexion Extension ◽  
Force Components

With the help of finite element (FE) computational models of femur, pelvis or hip joint to perform quasi-static stress analysis during the entire gait cycle, muscle force components (X, Y, Z) acting on the hip joint and pelvis are to be known. Most of the investigators have presented only the net muscle force magnitude during gait. However, for the FE software, either muscle force components (X, Y, Z) or three angles for the muscle line of action are required as input. No published algorithm (with flowchart) is readily available to calculate the required muscle force components for FE analysis. As the femur rotates about the hip center during gait, the lines of action for 27 muscle forces are also variable. To find out the variable lines of action and muscle force components (X, Y, Z) with directions, an algorithm was developed and presented here with detailed flowchart. We considered the varying angles of adduction/abduction, flexion/extension during gait. This computer program, obtainable from the first author, is able to calculate the muscle force components (X, Y, Z) as output, if the net magnitude of muscle force, hip joint orientations during gait and muscle origin and insertion coordinates are provided as input.

Verification of Predicted Knee Replacement Kinematics During Simulated Gait in the Kansas Knee Simulator

2010 ◽  
Vol 132 (8) ◽  
Author(s):  
Jason P. Halloran ◽  
Chadd W. Clary ◽  
Lorin P. Maletsky ◽  
Mark Taylor ◽  
Anthony J. Petrella ◽  
...  
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Knee Replacement ◽  
Degrees Of Freedom ◽  
Computational Models ◽  
Evaluation Process ◽  
Element Model ◽  
Explicit Finite Element ◽  
Knee Simulator ◽  
Flexion Extension

Evaluating total knee replacement kinematics and contact pressure distributions is an important element of preclinical assessment of implant designs. Although physical testing is essential in the evaluation process, validated computational models can augment these experiments and efficiently evaluate perturbations of the design or surgical variables. The objective of the present study was to perform an initial kinematic verification of a dynamic finite element model of the Kansas knee simulator by comparing predicted tibio- and patellofemoral kinematics with experimental measurements during force-controlled gait simulation. A current semiconstrained, cruciate-retaining, fixed-bearing implant mounted in aluminum fixtures was utilized. An explicit finite element model of the simulator was developed from measured physical properties of the machine, and loading conditions were created from the measured experimental feedback data. The explicit finite element model allows both rigid body and fully deformable solutions to be chosen based on the application of interest. Six degrees-of-freedom kinematics were compared for both tibio- and patellofemoral joints during gait loading, with an average root mean square (rms) translational error of 1.1 mm and rotational rms error of 1.3 deg. Model sensitivity to interface friction and damping present in the experimental joints was also evaluated and served as a secondary goal of this paper. Modifying the metal-polyethylene coefficient of friction from 0.1 to 0.01 varied the patellar flexion-extension and tibiofemoral anterior-posterior predictions by 7 deg and 2 mm, respectively, while other kinematic outputs were largely insensitive.

scholarly journals Biomechanical Evaluation of Cortical Bone Trajectory Fixation with Traditional Pedicle Screw in the Lumbar Spine: A Finite Element Study

2021 ◽  
Vol 11 (22) ◽  
pp. 10583
Author(s):  
Kuo-Chih Su ◽  
Kun-Hui Chen ◽  
Chien-Chou Pan ◽  
Cheng-Hung Lee
Keyword(s):  
Finite Element ◽  
Lumbar Spine ◽  
Cortical Bone ◽  
Pedicle Screw ◽  
Spinal Surgery ◽  
Pedicle Screws ◽  
Element Model ◽  
Cortical Bone Trajectory ◽  
Significant Difference ◽  
Flexion Extension

Cortical bone trajectory (CBT) is increasingly used in spinal surgery. Although there are many biomechanical studies, the biomechanical effect of CBT in combination with traditional pedicle screws is not detailed. Therefore, the purpose of this study was to investigate the effects of the traditional pedicle screw and CBT screw implantation on the lumbar spine using finite element methods. Based on the combination of the traditional pedicle screw and the CBT system implanted into the lumbar spine, four finite element spinal lumbar models were established. The models were given four different load conditions (flexion, extension, lateral bending, and axial rotation), and the deformation and stress distribution on the finite element model were observed. The results show that there was no significant difference in the structural stability of the lumbar spine model between the traditional pedicle screw system and the CBT system. In addition, CBT may reduce stress on the endplate. Different movements performed by the model may have significant biomechanical effects on the spine and screw system. Clinical spinal surgeons may also consider using the CBT system in revision spinal surgery, which may contribute to smaller wounds.

scholarly journals Design of a Metal 3D Printing Patient-Specific Repairing Thin Implant for Zygomaticomaxillary Complex Bone Fracture Based on Buttress Theory Using Finite Element Analysis

2020 ◽  
Vol 10 (14) ◽  
pp. 4738
Author(s):  
Yu-Tzu Wang ◽  
Chih-Hao Chen ◽  
Po-Fang Wang ◽  
Chien-Tzung Chen ◽  
Chun-Li Lin
Keyword(s):  
Finite Element ◽  
Topology Optimization ◽  
Biomechanical Analysis ◽  
Patient Specific ◽  
Element Analysis ◽  
Posterior Teeth ◽  
Frontal Process ◽  
Metal 3D Printing ◽  
Stress Variations ◽  
Zygomaticomaxillary Complex

This study developed a zygomaticomaxillary complex (ZMC) patient-specific repairing thin (PSRT) implant based on the buttress theory by integrating topology optimization and finite element (FE) analysis. An intact facial skeletal (IFS) model was constructed to perform topology optimization to obtain a hollow skeleton (HS) model with the structure and volume optimized. The PSRT implant was designed based on the HS contour which represented similar trends as vertical buttress pillars. A biomechanical analysis was performed on a ZMC fracture fixation with the PSRT implant and two traditional mini-plates under uniform axial loads applied on posterior teeth with 250 N. Results indicated that the variation in maximum bone stress and model volume between the IFS and HS models was 15.4% and 75.1%, respectively. Small stress variations between the IFS model and repairing with a PSRT implant (2.75–26.78%) were found for compressive stress at frontal process and tensile stress at the zygomatic process. Comparatively, large stress variations (30.67–96.26%) with different distributions between the IFS model and mini-plate models were found at the corresponding areas. This study concluded that the main structure/contour design of the ZMC repair implant according to the buttress position and orientation can obtain a favorable mechanical behavior.

scholarly journals Patient-Specific CT-Based Fluid-Structure-Interaction Aorta Model to Quantify Mechanical Conditions for the Investigation of Ascending Aortic Dilation in TOF Patients

2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Heng Zuo ◽  
Yunfei Ling ◽  
Peng Li ◽  
Qi An ◽  
Xiaobo Zhou
Keyword(s):  
Large Scale ◽  
Computational Models ◽  
Color Doppler ◽  
Systolic Pressure ◽  
Patient Specific ◽  
Mean Flow ◽  
Aortic Dilation ◽  
Aortic Diseases ◽  
Biomechanical Models ◽  
Velocity Magnitude

Background. Some adult patients with Tetralogy of Fallot (TOF) were found to simultaneously develop ascending aortic dilation. Severe aortic dilation would lead to several aortic diseases, including aortic aneurysm and dissection, which seriously affect patients’ living quality and even cause patients’ death. Current practice guidelines of aortic-dilation-related diseases mainly focus on aortic diameter, which has been found not always a good indicator. Therefore, it may be clinically useful to identify some other factors that can potentially better predict aortic response to dilation. Methods. 20 TOF patients scheduled for TOF repair surgery were recruited in this study and were divided into dilated and nondilated groups according to the Z scores of ascending aorta diameters. Patient-specific aortic CT images, pressure, and flow rates were used in the construction of computational biomechanical models. Results. Simulation results demonstrated a good coincidence between numerical mean flow rate at inlet and the one obtained from color Doppler ultrasonography, which implied that computational models were able to simulate the movement of the aorta and blood inside accurately. Our results indicated that aortic stress can effectively differentiate patients of the dilated group from the ones of the nondilated group. Mean ascending aortic stress-P1 (maximal principal stress) from the dilated group was 54% higher than that from the nondilated group (97.97 kPa vs. 63.47 kPa, p value = 0.044) under systolic pressure. Velocity magnitude in the aorta and aortic wall displacement of the dilated group were also greater than those of the nondilated group with p value < 0.1. Conclusion. Computational modeling and ascending aortic biomechanical factors may be used as a potential tool to identify and analyze aortic response to dilation. Large-scale clinical studies are needed to validate these preliminary findings.

The Patient-Specific Brace Design and Biomechanical Analysis of Adolescent Idiopathic Scoliosis

2009 ◽  
Vol 131 (4) ◽  
Author(s):  
Wen-Zhong Nie ◽  
Ming Ye ◽  
Zu-De Liu ◽  
Cheng-Tao Wang
Keyword(s):  
Finite Element ◽  
Measurement System ◽  
Element Model ◽  
Biomechanical Study ◽  
Biomechanical Analysis ◽  
Patient Specific ◽  
Sacral Slope ◽  
Element Analysis ◽  
Biomechanical Behavior ◽  
Idiopathic Adolescent Scoliosis

Brace application has been reported to be an effective approach in treating mild to moderate idiopathic adolescent scoliosis. However, little attention is focused on the biomechanical study of patient-specific brace treatment. The purpose of this study was to propose a design method of personalized brace and to analyze its biomechanical behavior and to compare the brace forces with the I-Scan measurement system. Based on a three-dimensional patient-specific finite element model of the spine, rib cage, pelvis, and abdomen, a parametric patient-specific model of a thoracolumbosacral orthosis was built. The interaction between the torso and the brace was modeled by surface-to-surface contact interface. Three standard strap tensions (20 N, 40 N, and 60 N) were loaded on the back of the brace to simulate the strap tension. The I-Scan distribution pressure measurement system was used to measure the different region pressures, and the equivalent forces in these regions were calculated. The spinal curve changes and the forces acted on the brace generated by the strap tension were evaluated and compared with the measurement. The reduction in the coronal curvature was about 60% for a strap tension of 60 N. The sacral slope and the lordosis were partially reduced in this case, but the kyphosis had no obvious change. The brace slightly modified the axial rotation at the apex of the scoliotic curve. The forces generated in finite element analysis were approximately in good agreement with the measurement. The design and biomechanical analysis methods of patient-specific brace should be useful in the design of more effective braces.

Parallelizing a finite element solver in computational hemodynamics

2016 ◽  
Vol 32 (3) ◽  
pp. 351-362 ◽  
Author(s):  
F Auricchio ◽  
M Ferretti ◽  
A Lefieux ◽  
M Musci ◽  
A Reali ◽  
...  
Keyword(s):  
Finite Element ◽  
Software Architecture ◽  
Parallel Implementation ◽  
Numerical Models ◽  
Point Of View ◽  
Patient Specific ◽  
Computer Engineering ◽  
Clinical Environment ◽  
Aortic Diseases ◽  
Parallel Methods

In the last 20 years, a new approach has emerged to investigate the physiopathology of circulation. By merging medical images with validated numerical models, it is possible to support doctors’ decision-making process. The iCardioCloud project aims at establishing a computational framework to perform a complete patient-specific numerical analysis, specially oriented to aortic diseases (like dissections or aneurysms) and to deliver a compelling synthesis. The project can be considered a pioneering example of a Computer Aided Clinical Trial: i.e., a comprehensive analysis of patients where the level of knowledge extracted by traditional measures and statistics is enhanced through the massive use of numerical modeling. From a computer engineering point of view, iCardioCloud faces multiple challenges. First, the number of problems to solve for each patient is significantly huge – this is typical of computational fluid dynamics (CFD) – and it requires parallel methods. In addition, working in a clinical environment demands efficiency as the timeline requires rapid quantitative answers (as may happen in an emergency scenario). It is therefore mandatory to employ high-end parallel systems, such as large clusters or supercomputers. Here we discuss a parallel implementation of an application within the iCardioCloud project, built with a black-box approach – i.e., by assembling and configuring existing packages and libraries and in particular LifeV, a finite element library developed to solve CFD problems. The goal of this paper is to describe the software architecture underlying LifeV and to assess its performance and the most appropriate parallel paradigm. This paper is an extension of a previous work presented at the PBio 2015 Conference. This revision extends the description of the software architecture and discusses several new serial and parallel optimizations to the application. We discuss the introduction of hybrid parallelism in order to mitigate some performance problems previously experienced.

scholarly journals Evaluation of a modified Cheatham-Platinum stent for the treatment of aortic coarctation by finite element modelling

2018 ◽  
Vol 7 ◽  
pp. 204800401877395 ◽  
Author(s):  
Barbara EU Burkhardt ◽  
Nicholas Byrne ◽  
Marí Nieves Velasco Forte ◽  
Francesco Iannaccone ◽  
Matthieu De Beule ◽  
...  
Keyword(s):  
Finite Element ◽  
Aortic Coarctation ◽  
Computational Models ◽  
Three Dimensional ◽  
Computational Modelling ◽  
Patient Specific ◽  
Stent Design ◽  
Initial Length ◽  
Element Analysis

Objectives Stent implantation for the treatment of aortic coarctation has become a standard approach for the management of older children and adults. Criteria for optimal stent design and construction remain undefined. This study used computational modelling to compare the performance of two generations of the Cheatham-Platinum stent (NuMED, Hopkinton, NY, USA) deployed in aortic coarctation using finite element analysis. Design Three-dimensional models of both stents, reverse engineered from microCT scans, were implanted in the aortic model of one representative patient. They were virtually expanded in the vessel with a 16 mm balloon and a pressure of 2 atm. Results The conventional stent foreshortened to 96.5% of its initial length, whereas the new stent to 99.2% of its initial length. Diameters in 15 slices across the conventional stent were 11.6–15 mm (median 14.2 mm) and slightly higher across the new stent: 10.7–15.3 mm (median 14.5 mm) (p= 0.021). Apposition to the vessel wall was similar: conventional stent 31.1% and new stent 28.6% of total stent area. Conclusions The new design Cheatham-Platinum stent showed similar deployment results compared to the conventional design. The new stent design showed slightly higher expansion, using the same delivery balloon. Patient-specific computational models can be used for virtual implantation of new aortic stents and promise to inform subsequent in vivo trials.

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