Biomécanique de l'action musculaire du rachis cervical

12ème Congrès National de la Société Française de Médecine Manuelle Orthopédique et Ostéopathique, PARIS, FRANCE, 12-/10/2018 - 14/10/2018Des modèles numériques modélisant le comportement mécanique du corps humain sont utilisés depuis de nombreuses années dans l'industrie automobile pour prédire le risque lésionnel en situation de choc. Les progrès réalisés en termes de validation de ces modèles sont tels que le ?virtual-testing' a récemment fait son apparition au sein du programme d'évaluation de véhicules EuroNCAP pour compléter, et remplacer à terme, les essais de crash-test sur mannequins. Le transfert de ces outils vers le champ clinique fait face à des défis ayant trait à des besoins propres à ces applications. Ceux-ci incluent non seulement le besoin d'une modélisation plus détaillée et spécifique à chaque patient mais également, comme nous essayerons de le présenter au travers d'une réflexion portant sur les évolutions récentes de la modélisation biomécanique du cou, le besoin d'une prise en compte des effets 3D complexes qui résultent d'une activation synergique des muscles propre à chaque tâche de la vie courante. Les enjeux portent, à terme, sur une meilleure prédiction des sollicitations mécaniques du rachis, que ce soit par exemple pour la réalisation d'essais cliniques ?in-silico' de dispositifs médicaux visant à réparer une instabilité traumatique ou pour l'aide à l'évaluation prédictive d'une stratégie de traitement d'une dystonie musculaire

VARIATION IN LANDING DURING GYMNASTICS SKILLS

The aim of this study was to examine joint motion during landing from a variety of gymnastics skills. Twelve gymnasts performed a range of gymnastics skills with a landing component. Joint angles of the ankle, knee and hip were examined during landing from five different skills. There were significant differences between skills at all joints for peak flexion and extension (ankle, knee and hip:

METHOD FOR THE DETECTION OF FATIGUE DURING GYMNASTICS TRAINING

The purpose of this study was to determine if acceleration measured at the pelvis was a suitable indicator of fatigue in gymnasts. Fourteen gymnasts performed vertical jumps and drop landings pre and post a fatiguing jumping activity. Peak acceleration during landing for jumps and drops increased significantly after fatiguing activity. Acceleration is a tool that can be collected with limited disruption to gymnastics training and an increase in peak acceleration during landing of simple jumps appears to be a useful tool for determining whether gymnasts are fatigued

METHOD FOR ANALYSING THE RISK OF OVERUSE INJURY IN GYMNASTICS

The purpose of this study was to propose and assess a method for the evaluation of all loads experienced during gymnastics training. The method is based on the measurement of acceleration on the gymnast. Twelve gymnasts performed a range of gymnastics skills with an impact component. Ground reaction forces and acceleration at the pelvis were measured. There were significant correlations between peak GRF and peak acceleration during landing from gymnastics skills for individual participants. This testing showed the potential for this method to be applied in a study of injury risk factors outside the laboratory environment. At present, this relationship means that acceleration can be used as an estimation of force, after calibrating acceleration to ground reaction force for the individual

Short isthmic versus long trans-isthmic C2 screw: anatomical and biomechanical evaluation

INTRODUCTION: The Harms technique is now considered as the gold standard to stabilize C1-C2 cervical spine. It has been reported to decrease the risk of vertebral artery injury. However, the risk of vascular injury does not totally disappear, particularly due to the proximity of the trans-isthmic C2 screw with the foramen transversarium of C2. In order to decrease this risk of vertebral artery injury, it has been proposed to use a shorter screw which stops before the foramen transversarium. OBJECT: The main objective was to compare the pull-out strength of long trans-isthmic screw (LS) versus short isthmic screw (SS) C2 screw. An additional morphological study was also performed. METHOD: Thirteen fresh-frozen human cadaveric cervical spines were included in the study. Orientation, width and height of the isthmus of C2 were measured on CT scan. Then, 3.5-mm titanium screws were inserted in C2 isthmus according to the Harms technique. Each specimen received a LS and a SS. The side and the order of placement were determined with a randomization table. Pull-out strengths and stiffness were evaluated with a testing machine, and paired samples were compared using Wilcoxon signed-rank test and also the Kaplan-Meier method. RESULTS: The mean isthmus transversal orientation was 20° ± 6°. The mean width of C2 isthmus was less than 3.5 mm in 35 % of the cases. The mean pull-out strength for LS was 340 ± 85 versus 213 ± 104 N for SS (p = 0.004). The mean stiffness for the LS was 144 ± 40 and 97 ± 54 N/mm for the SS (p = 0.02). DISCUSSION: The pull-out strength of trans-isthmic C2 screws was significantly higher (60 % additional pull-out resistance) than SSs. Although associated with an inferior resistance, SSs may be used in case of narrow isthmus which contraindicates 3.5-mm screw insertion but does not represent the first option for C2 instrumentation. LEVEL OF EVIDENCE: Level V

D3.8 Final version of the personalization and positioning software tool with documentation. PIPER EU Project

The aim of this report is to provide an overview of the final version of the PIPER framework and application. The software, along with its documentation, and not the report, constitutes the main part of the deliverable. The software and documentation were already distributed at the Final Workshop and online (under the Open Source license GPLv2 or later for the software, and the GNU FDL 1.3 license for the documentation). The documentation includes detailed descriptions of the framework principles, user interface, metadata, along with the modules and their parameters. It also includes application scenarios (called workflows). Information about the use of the modules is complemented by Tutorials that were developed as part of WP1 (online on the wiki) and explanatory videos were developed as part of WP4 (videos of the final workshop, now available on YouTube). The headers in the source code files (also available online) list the main contributors to the software. The report will therefore not provide details about information that is already available elsewhere but will only provide a very brief summary of the functionalities available. Some of the descriptions are excerpts of the manual

Directorium divini cultus ad Cathedralis Ecclesiae Minoriccensis : eiusque Dioecesis usum

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Contribution à l'étude du comportement du rachis cervical soumis à un choc

Injuries at the cervical level are often related with motor accidents, where they represent 15% of severe injuries and more than 50% of compensation claims. The associated injury mechanisms are not yet fully understood, and clinicians as well as insurers are in need of criteria to allow a better assessment of impact injuries, in particular for which concerns whiplash. Our aim is to explore injury mechanisms that occur during this last kind of impact, in improving and developing Finite-Element models of the human head/neck complex. This was performed by identifying possible mechanisms of injury, which were compared to simulation results. Then, the influence of extrinsic and intrinsic parameters on injury risk was taken into account, allowing to emphasize the potential of defining local criteria in this context. In particular, the study of the influence of morphology led to an evolution of the models towards personalization, based on a geometric reconstruction from stereo-radiography.Dans les accidents de la route, les lésions cervicales représentent 15% des lésions traumatiques graves et plus de 50% des demandes de remboursements. Les mécanismes lésionnels associés sont encore mal connus, et médecins et assureurs sont demandeurs de critères quantifiant les lésions de type whiplash. Le but de cette étude est de contribuer à l'amélioration de modèles Eléments-Finis permettant d'explorer les mécanismes lésionnels survenant lors de ces sollicitations. A cet effet des mécanismes lésionnels probables ont été identifiés et comparés aux résultats de simulations numériques. L'influence de paramètres extrinsèques et intrinsèques sur le risque lésionnel associé a été évaluée, permettant de mettre en relief l'intérêt d'une étude de critères locaux dans ce contexte. En particulier, l'étude de l'influence de la morphologie a été accompagnée d'une évolution des modèles vers la personnalisation, basée sur la reconstruction géométrique d'un sujet à partir de stéréo-radiographies

Accounting for task-related active muscle force distribution patterns in a FE model of the neck

8th World Congress of Biomechanics, DUBLIN, IRELANDE, 08-/07/2018 - 12/07/2018This abstract presents the ingoing development of a 3D active musculoskeletal FE model of the neck in the FE code LS-Dyn

Contribution à l'étude du comportement du rachis cervical soumis à un choc

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