Fast Subject Specific Finite Element Mesh Generation of Knee Joint from Biplanar X-ray Images

Numerous finite element (FE) models of the knee joint have been developed to investigate knee pathology, post-surgery assessment and natural knee biomechanics. However, because of the extensive computational effort required for preparing subject specific model from CT-scan or MRI data, most of the models in literature are done only for one subject resulting in poor validation of the model and limits the predictive power of the conclusions. Biplanar X-ray is a promising alternative to perform 3D reconstruction of bony structures because of low radiation dose and very less reconstruction time [1]. Moreover, an accurate and fast computational mesh is a prerequisite for generating subject specific mesh in order to perform personalized FE analysis. Traditionally, both triangular/tetrahedral and quadrilateral/hexahedral FE elements are used for 3D mesh generation. But because of distinct numerical advantages quadrilateral/hexahedral elements are preferred to avoid numerical instability, specifically for problems involving high strains at soft tissues [2]. The aim of the current study is to develop fast and automatic subject specific mesh for knee joint from biplanar X-ray images. This approach was successfully tested for 6 cadaveric specimen, where from the biplanar radiographic images of each, 3D reconstruction models were built with a mean time of about 10 min for each specimen by adapting the strategy of [1]. From the reconstruction models, subject specific mesh (4 noded shell) for bony and cartilage structures were generated based on the mapping from the generic model to subject specific model with about 10 sec of time for each specimen (Fig. 1). Both the meniscus were meshed with 8 noded hex elements using the nodes of femoral and tibial cartilage in a dedicated Matlab code with numerical cost of almost 1 min. So, a total of about 12 min computational time was required to build each subject specific knee from 3D reconstruction to mesh generation which is promising for clinical applications. Quality of mesh for individual specimen was also checked using mesh quality indicators (Jacobian ratio, aspect ratio etc.) and surface representation accuracy, which showed less than 1% (warning only) and 0.8 mm (at soft tissue regions) respectively for individual specimen

Development and evaluation of a new procedure for subject-specific tensioning of finite element knee ligaments

Subject-specific tensioning of ligaments is essential for the stability of the knee joint and represents a challenging aspect in the development of finite element models. We aimed to introduce and evaluate a new procedure for the quantification of ligament prestrains from biplanar X-ray and CT data. Subject-specific model evaluation was performed by comparing predicted femorotibial kinematics with the in vitro response of six cadaveric specimens. The differences obtained using personalized models were comparable to those reported in similar studies in the literature. This study is the first step toward the use of simplified, personalized knee FE models in clinical context such as ligament balancing

CONTRIBUTION TO PERSONALIZED FINITE ELEMENT BASED MUSCULOSKELETAL MODELING OF THE LOWER LIMB

Le trouble musculosquelettique du membre inférieur est l'un des fardeaux de santé les plus courants pouvant entraîner une déficience fonctionnelle chez un individu. Bien que diverses options de gestion opérationnelle soient disponibles, il ne semble pas y avoir unanimité sur une procédure particulière qui servirait au mieux les intérêts de tous. Pour évaluer objectivement les troubles et planifier efficacement les interventions chirurgicales, il est essentiel de comprendre la biomécanique des membres inférieurs dans des conditions de charge physiologique. Avec cette motivation, ce travail de thèse vise à développer un cadre complet de modélisation musculosquelettique du membre inférieur basé sur les éléments finis. La première phase du travail de thèse est axée sur le développement et l'évaluation de modèles personnalisés d'éléments finis en flexion passive. De nouvelles approches sont proposées et évaluées pour le développement rapide de modèles axés sur la géométrie et les propriétés des ligaments. Dans la deuxième phase, une nouvelle approche basée sur les éléments finis pour la compensation des artefacts des tissus mous est proposée et évaluée. Cette contribution a permis de compenser efficacement les artefacts des tissus mous dans l'analyse du mouvement en tenant compte de la spécificité du sujet. La troisième phase du travail de thèse est consacrée à l'application clinique, où l'utilité du système radiographique biplan dans l'évaluation de l'alignement des implants de l'arthroplastie totale du genou est brièvement explorée. Dans l'ensemble, ce travail de thèse peut aider à estimer et à comprendre avec précision la biomécanique des membres inférieurs dans des conditions de charge cliniquement pertinentes, et à rapprocher le modèle de la routine clinique.Musculoskeletal disorder of the lower limb is one of the most common health burdens that may lead to functional impairment in an individual. Although various operative management options are available, there seems no unanimity on a particular procedure that serves the best. To objectively assess disorders and effectively plan surgeries, it is essential to understand lower limb biomechanics under physiological loading conditions. With that motivation, this PhD aims to develop a comprehensive finite element based musculoskeletal modeling framework of the lower limb. The first phase of the PhD focuses on the development and evaluation of subject-specific finite element models under passive flexion. Novel approaches are proposed and evaluated for fast model development focusing on geometry and ligament properties. In the second phase, a novel finite element based approach for soft tissue artifact compensation is proposed and evaluated. This contribution allowed to effectively compensate for soft tissue artifact in motion analysis by taking subject specificity into account. The third phase of the PhD is dedicated to clinical application, where the utility of the biplanar X-ray system in evaluating Total Knee Arthroplasty implant alignment is briefly explored. Overall, this PhD may help to accurately estimate and understand lower limb biomechanics under clinically relevant loading conditions, and bring the model a step closer to clinical routine

Contribution à la modélisation musculosquelettique personnalisée du membre inférieur par éléments finis

Musculoskeletal disorder of the lower limb is one of the most common health burdens that may lead to functional impairment in an individual. Although various operative management options are available, there seems no unanimity on a particular procedure that serves the best. To objectively assess disorders and effectively plan surgeries, it is essential to understand lower limb biomechanics under physiological loading conditions. With that motivation, this PhD aims to develop a comprehensive finite element based musculoskeletal modeling framework of the lower limb. The first phase of the PhD focuses on the development and evaluation of subject-specific finite element models under passive flexion. Novel approaches are proposed and evaluated for fast model development focusing on geometry and ligament properties. In the second phase, a novel finite element based approach for soft tissue artifact compensation is proposed and evaluated. This contribution allowed to effectively compensate for soft tissue artifact in motion analysis by taking subject specificity into account. The third phase of the PhD is dedicated to clinical application, where the utility of the biplanar X-ray system in evaluating Total Knee Arthroplasty implant alignment is briefly explored. Overall, this PhD may help to accurately estimate and understand lower limb biomechanics under clinically relevant loading conditions, and bring the model a step closer to clinical routine.Le trouble musculosquelettique du membre inférieur est l'un des fardeaux de santé les plus courants pouvant entraîner une déficience fonctionnelle chez un individu. Bien que diverses options de gestion opérationnelle soient disponibles, il ne semble pas y avoir unanimité sur une procédure particulière qui servirait au mieux les intérêts de tous. Pour évaluer objectivement les troubles et planifier efficacement les interventions chirurgicales, il est essentiel de comprendre la biomécanique des membres inférieurs dans des conditions de charge physiologique. Avec cette motivation, ce travail de thèse vise à développer un cadre complet de modélisation musculosquelettique du membre inférieur basé sur les éléments finis. La première phase du travail de thèse est axée sur le développement et l'évaluation de modèles personnalisés d'éléments finis en flexion passive. De nouvelles approches sont proposées et évaluées pour le développement rapide de modèles axés sur la géométrie et les propriétés des ligaments. Dans la deuxième phase, une nouvelle approche basée sur les éléments finis pour la compensation des artefacts des tissus mous est proposée et évaluée. Cette contribution a permis de compenser efficacement les artefacts des tissus mous dans l'analyse du mouvement en tenant compte de la spécificité du sujet. La troisième phase du travail de thèse est consacrée à l'application clinique, où l'utilité du système radiographique biplan dans l'évaluation de l'alignement des implants de l'arthroplastie totale du genou est brièvement explorée. Dans l'ensemble, ce travail de thèse peut aider à estimer et à comprendre avec précision la biomécanique des membres inférieurs dans des conditions de charge cliniquement pertinentes, et à rapprocher le modèle de la routine clinique

Stability criteria compared using markerless and marker-based data

SB 2022, 47eme Congrès de la Société de Biomécanique, Monastir, TUNISIE, 26-/10/2022 - 28/10/2022In this study Stability criteria compared using markerless and marker-based data, we used this approach to quantify the control of sagittal-plane WBAM during stepping. We hypothesized that old adults would control this variable less compared to younger adults. Furthermore, we assumed that the poorer control of WBAM would be correlated with the larger range of WBAM in older adults

Accuracy of a markerless motion capture system in estimating upper extremity kinematics during boxing

Kinematic analysis of the upper extremity can be useful to assess the performance and skill levels of athletes during combat sports such as boxing. Although marker-based approach is widely used to obtain kinematic data, it is not suitable for "in the field" activities, i.e., when performed outside the laboratory environment. Markerless video-based systems along with deep learning-based pose estimation algorithms show great potential for estimating skeletal kinematics. However, applicability of these systems in assessing upper-limb kinematics remains unexplored in highly dynamic activities. This study aimed to assess kinematics of the upper limb estimated with a markerless motion capture system (2D video cameras along with commercially available pose estimation software Theia3D) compared to those measured with marker-based system during "in the field" boxing. A total of three elite boxers equipped with retroreflective markers were instructed to perform specific sequences of shadow boxing trials. Their movements were simultaneously recorded with 12 optoelectronic and 10 video cameras, providing synchronized data to be processed further for comparison. Comparative assessment showed higher differences in 3D joint center positions at the elbow (more than 3 cm) compared to the shoulder and wrist

Fast Subject Specific Finite Element Mesh Generation of Knee Joint from Biplanar X-ray Images

International audienceNumerous finite element (FE) models of the knee joint have been developed to investigate knee pathology, post-surgery assessment and natural knee biomechanics. However, because of the extensive computational effort required for preparing subject specific model from CT-scan or MRI data, most of the models in literature are done only for one subject resulting in poor validation of the model and limits the predictive power of the conclusions. Biplanar X-ray is a promising alternative to perform 3D reconstruction of bony structures because of low radiation dose and very less reconstruction time [1]. Moreover, an accurate and fast computational mesh is a prerequisite for generating subject specific mesh in order to perform personalized FE analysis. Traditionally, both triangular/tetrahedral and quadrilateral/hexahedral FE elements are used for 3D mesh generation. But because of distinct numerical advantages quadrilateral/hexahedral elements are preferred to avoid numerical instability, specifically for problems involving high strains at soft tissues [2]. The aim of the current study is to develop fast and automatic subject specific mesh for knee joint from biplanar X-ray images. This approach was successfully tested for 6 cadaveric specimen, where from the biplanar radiographic images of each, 3D reconstruction models were built with a mean time of about 10 min for each specimen by adapting the strategy of [1]. From the reconstruction models, subject specific mesh (4 noded shell) for bony and cartilage structures were generated based on the mapping from the generic model to subject specific model with about 10 sec of time for each specimen (Fig. 1). Both the meniscus were meshed with 8 noded hex elements using the nodes of femoral and tibial cartilage in a dedicated Matlab code with numerical cost of almost 1 min. So, a total of about 12 min computational time was required to build each subject specific knee from 3D reconstruction to mesh generation which is promising for clinical applications. Quality of mesh for individual specimen was also checked using mesh quality indicators (Jacobian ratio, aspect ratio etc.) and surface representation accuracy, which showed less than 1% (warning only) and 0.8 mm (at soft tissue regions) respectively for individual specimen

IMPACT OF PERSONALISATION OF GEOMETRY ON THE PASSIVE KINEMATIC RESPONSE OF THE KNEE JOINT IN FLEXION-EXTENSION

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Automatic Estimation of Center of Mass from Multi-Camera Video System

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