185 research outputs found
HASPA Dataset (kinematic and kinetic data for spastic patients)
No full textThis repository contains kinematic and kinetic data of the lower limb of spastic adult patients. This dataset was acquired during the ANR French project named HASPA (HAptic simulator for SPAsticity Training). Within the project, the objective of this dataset was to provide patterns for a physical simulator used for training physiotherapists and doctors to diagnose spasticity of the lower limb. This dataset including objective biomechanical and neurophysiological parameters for adults suffering from spasticity in the lower limb can be used to investigate variables featuring this population
Une analytique du pire que mal
No full text<p><strong>Résumé</strong></p><p>Cet entretien aborde les éléments principaux du livre de Pierre-Henri Castel, <i>Pervers, analyse d'un concept</i>. Il traite de la méthode philosophique de l'auteur, une analytique du « pire que mal » qui permet de comprendre les personnes perverses dans leurs relations avec leurs victimes. Cette perspective théorique a des implications pratiques sur la façon de comprendre les coupables lors des procès qui jugent leurs actes.</p><p><strong>Abstract</strong></p><p>This interview discusses the main elements of Pierre-Henri Castel's book, <i>Pervers, analyse d'un concept</i>. It deals with the philosophical method of the author, an analysis of the "worse than bad" which allows to understand perverse people in their relations with their victims. This theoretical perspective has practical implications for how to understand perpetrators during the trials that judge their actions. </p>
Laxity and injury response of knee ligaments in lateral impact conditions
No full textLe genou est l'une des régions d'intérêt pour l'évaluation de la sécurité des piétons. Les essais précédemment réalisés dans la littérature pour étudier la réponse lésionnelle du genou dans une configuration de choc piéton, ne tiennent pas compte de la flexion du genou et testent ce dernier uniquement en extension complète. L’effet du recrutement successif des fibres ligamentaires en fonction du positionnement initial du genou n’a pas été considéré non plus dans ces études. Cependant, l’existence d’un lien entre les conditions initiales dans lesquelles le genou est placé (flexion, orientation relative des insertions, direction du chargement) et la réponse mécanique de ce dernier (rigidité linéaire, force in situ…) est établi dans la littérature. Ainsi, un nouveau protocole expérimental est proposé afin (1) d’évaluer de manière non-lésionnelle la laxité et le début de chargement des ligaments en fonction de la position initiale du genou et de la direction de chargement, (2) de caractériser l’effet de la position initiale sur la réponse lésionnelle des ligaments notamment sur leur élongation à la rupture. Les résultats de la laxité sont combinés à l’élongation à la rupture pour regarder si la laxité permet d’expliquer les différences de réponse lésionnelle observées en fonction de la position initiale du genou. Une étude paramétrique par modélisation numérique a permis de définir les choix expérimentaux de l’étude : flexion 4-points (4P) comme mode de chargement pour les essais à rupture, la rotation interne-externe et le déplacement proximal-distal doivent rester libres sur le montage, et 10° et 45° de flexion pour le positionnement initial du genou. Douze genoux ont été testés selon ce protocole. La définition de la laxité des ligaments sur la base de la déformation osseuse près des insertions ligamentaires a été plus fructueuse pour les ligaments collatéraux, mais plus compliquée pour les ligaments croisés. Ainsi, il était difficile d’exploiter les valeurs de laxité obtenues pour expliquer les différences observées entre 10° et 45° au niveau des élongations à la rupture des ligaments. Les essais de flexion 4P sur genou isolé ont donné lieu à des lésions ligamentaires et à une cinématique d’essai proches de celles observées dans les essais corps entier. Ces résultats constituent une base de validation pour les modèles éléments finis du genou qui pourront, après validation, être utilisés pour mieux investiguer l’effet de la laxité et élargir la base de données sur l’élongation à la rupture des ligaments. Des propositions d’amélioration du modèle de genou actuel sont fournies à l’issue d’une comparaison entre des simulations numériques réalisées dans les conditions des essais expérimentaux et les résultats de ces essais.The knee is one of the important regions in evaluating the pedestrian safety during lateral impacts. The knee was always fully extended when tested in pedestrian impact conditions in the literature. However, the knee response could be affected by several parameters including the knee initial position, the relative orientation of the ligament insertion points and the direction of the applied load. Those parameters are shown to modify the ligament mechanical properties and load/tension state as well. Based on that information, a new experimental protocol was proposed to (1) characterize the beginning of tension in the ligament with respect to the knee initial position and to the direction of the applied load, (2) to investigate how the knee initial position could affect the elongation at failure of the ligaments under lateral impact conditions. A series of numerical simulations was carried out to define the experimental choices associated with the protocol. Three main choices were made: the failure tests will be carried out on a 4-point bending fixture, the internal-external rotation and the distal-proximal translation should remain unconstrained in those tests, and the two knee initial positions will be 10° and 45° of knee flexion. Characterizing the knee ligaments laxity based on the bone strain near the ligament insertions sites was less complicated for the collateral ligaments compared to the cruciate ligaments. It was consequently difficult to use the laxity results to explain the differences in the elongation at failure between the two flexion angles (10° and 45°). However, the dynamic tests resulted in ligaments injuries and knee kinematics that were comparable to the ones observed in full body pedestrian impact tests. Hence, the obtained results could be used as a validation database for the current finite element knee models so that they could be used to further characterize the ligaments laxity and to generate more data on the ligaments failure response. Possible improvements of the knee ligaments representation in a finite element model are finally suggested based on the results of the knee model simulation under the experimental tests conditions
Identification and effects of the initial tension state in ligaments according to the lumbar spine posture
No full textL'apparition des modèles numériques de corps humain, en particulier par la méthode des éléments finis, a été bénéfique pour la biomécanique et l'ingénierie médicale. Ces modèles permettent de décrire le comportement mécanique des structures anatomiques, tout en prenant en compte différentes morphologies. Les modèles incluant une représentation de la colonne lombaire sont aujourd’hui largement utilisés en orthopédie (e.g. la conception d’implants), en ergonomie (e.g. prédiction des risques de douleur) et en choc automobile (e.g. la conception des dispositifs de retenue). Mais ces modèles supposent presque toujours un état initial de contrainte nulle. Pour la colonne lombaire, ils ne prennent pas en compte ni les chargements initiaux des ligaments rachidiens pour une posture initiale donnée, ni les pré-chargements résultant d’un changement de posture initiale. Or, les ligaments jouent un rôle crucial dans la stabilité et la réponse mécanique de la colonne vertébrale. Le projet de thèse vise à identifier et évaluer les états initiaux des ligaments lombaires en fonction de la posture, en utilisant des modèles par éléments finis. Le travail de recherche est divisé en trois parties : l'identification des états initiaux des ligaments, la modélisation de ces états et l'évaluation des réponses des modèles. La thèse est structurée en cinq chapitres. Les deux premiers chapitres fournissent un rappel anatomique du rachis lombaire et une revue de littérature approfondie sur la modélisation et les caractéristiques des ligaments lombaires. Le troisième chapitre étudie les différentes méthodes de modélisation des ligaments, afin de mieux comprendre leurs effets et présente une méthode de détermination des laxités ligamentaires pour répondre aux exigences d’amplitude de mouvement. La méthode, générique, peut être adaptée à tout type de modèle et de structures anatomiques, et renforcer par des nouvelles hypothèses. Le quatrième chapitre décrit l’effet des précédentes gammes de laxité et de prétension des ligaments sur des modèles locaux (de l’unité fonctionnelle au segment vertébral) et globaux (corps complet) : la réponse mécanique simulée est comparée à des données expérimentales de la littérature (cinématique, efforts facettaires, pression intra-discale, et risque à rupture des ligaments). Le cinquième chapitre propose de déterminer la laxité des ligaments à partir de résultats expérimentaux détaillés et cohérents : cette base de données récente contient, pour plusieurs niveaux vertébraux, les géométries osseuses en position initiale et la caractérisation des unités fonctionnelles (pour plusieurs chargements) et de chacun de leurs ligaments (en traction). Ces travaux ont montré la nécessité de déterminer et de modéliser un état de pré-chargement initial dans les ligaments lombaires, pour améliorer le comportement des modèles numériques utilisés en biomécanique vertébrale et notre compréhension du rôle des différentes structures anatomiques du rachis.The emergence of numerical models of the human body, particularly using the finite element method, has proven to be beneficial for biomechanics and medical engineering. These models enable the description of the mechanical behavior of anatomical structures while considering various morphologies. Models that incorporate representations of the lumbar spine are now widely used in orthopedics (e.g., implant design), ergonomics (e.g., prediction of pain risks), and automotive crash analysis (e.g., restraint system design). However, these models almost always assume an initial state of zero stress. For the lumbar spine, they do not account for either the initial loading of spinal ligaments for a given posture or the preloads resulting from a change in the initial posture. Yet, ligaments play a crucial role in the stability and mechanical response of the vertebral column. The main objective of this thesis project is to identify and evaluate the initial states of the lumbar ligaments based on posture, using finite element models. The research work is divided into three parts: the identification of initial states of the ligaments, the modeling of these states, and the evaluation of the model responses. The thesis is structured into five chapters. The first two chapters provide an anatomical review of the lumbar spine and an in-depth literature review on the modeling and characteristics of lumbar ligaments. The third chapter explores various methods for modeling ligaments to better understand their effects and presents a method for determining ligament laxities to meet the requirements of motion range. The generic method can be adapted to any type of model and anatomical structures and can be reinforced by new assumptions. The fourth chapter describes the effect of different ranges of ligament laxity and pretension on local models (from functional units to vertebral segments) and global models (entire body): simulated mechanical responses are compared to experimental data from the literature (kinematics, facet joint forces, intra-discal pressure, and ligament rupture risk). The fifth chapter proposes to determine ligament laxity based on detailed and consistent experimental results: this recent database contains, for several vertebral levels, the initial bone geometries and characterization of functional units (for various loadings) and each of their ligaments (under tension).These studies have demonstrated the necessity of determining and modeling an initial preloading state in lumbar ligaments to improve the behavior of numerical models used in vertebral biomechanics and to enhance our understanding of the role of different anatomical structures in the spine
Deformable modelling of the musculoskeletal system of the lower limb
No full textLa modélisation du système musculo-squelettique est un outil permettant l'amélioration des connaissances du fonctionnement biomécanique des structures ostéo-articulaires et musculo- tendineuses. Nos travaux de recherche portent sur le développement d'une méthodologie de modélisation personnalisée, volumique, déformable et à capacité contractile du système musculo- squelettique du membre inférieur, intégrant l'ensemble des outils, le plus possible automatisés, de construction (basée sur l'imagerie médicale), de simulation (en couplage avec un modèle multi-corps dynamique) et d'analyse (comme la cartographie des raideurs locales dans le muscle) nécessaires à leur mise en œuvre dans le cadre d'études orthopédiquesMusculo-skeletal modeling can update our knowledge concerning the biomechanical behavior of the osteoarticular and musculotendinous structures. This research work is focus on the development of methodology and tools for the generation of a personalized model of the lower limb musculoskeletal system, taking account of the deformable and contractile behavior of the muscles. This workflow automatically builds the model dataset (from medical imagery), performs the simulations (coupled with a multibody dynamic model), and offers specific analysis tools (as local stiffness mapping in the active muscle) required for various orthopedic studie
A comparative biomechanical study of the Distal Tibia Nail against compression plating for the osteosynthesis of supramalleolar corrective osteotomies
No full textGreenfield J, Appelmann P, Lafon Y, Bruyere-Garnier K, Rommens PM, Kuhn S. A comparative biomechanical study of the Distal Tibia Nail against compression plating for the osteosynthesis of supramalleolar corrective osteotomies. Scientific reports. 2021;11(1): 18834.The Distal Tibia Nail (DTN; Mizuho, Japan) has demonstrated higher biomechanical stiffness to locking plates in previous research for A3 distal tibia fractures. It is here investigated as a fixation option for supramalleolar corrective osteotomies (SMOT). Sixteen Sawbones tibiae were implanted with either a DTN (n=8) or Medial Distal Tibia Plate (MDTP; n=8) and a SMOT simulated. Two surgical outcome scenarios were envisaged: "best-case" representing an intact lateral cortex, and "worst-case" representing a fractured lateral cortex. All samples were subjected to compressive (350N, 700N) and torsional (±4 Nm,±8 Nm) testing. Samples were evaluated using calculated construct stiffness from force-displacement data, interfragmentary movement and Von Mises' strain distribution. The DTN demonstrated a greater compressive stiffness for the best-case surgical scenario, whereas the MDTP showed higher stiffness (p<0.05) for the worst-case surgical scenario. In torsional testing, the DTN proved more resistant to torsion in the worst-case surgical setup (p<0.05) for both±4 Nm and±8Nm. The equivalent stiffness of the DTN against the MDTP supports the use of this implant for SMOT fixation and should be considered as a treatment option particularly in patients presenting vascularisation problems where the MDTP is an inappropriate choice. © 2021. The Author(s)
Biomechanical study of an implantable suspension for the preservation of the intervertebral discs in the treatment of infantile scoliosis
No full textLa scoliose infantile est une déformation rachidienne évolutive survenant chez l'enfant de moins de 3 ans. La technique de correction la plus répandue actuellement est celle des « tiges de croissance ». Cependant, la rigidité du matériel provoque la dégénérescence des disques intervertébraux, ce qui di-minue l'efficacité du traitement. Des études récentes ont montré l'effet bénéfique d'implants flexibles sur les disques. Notre équipe a donc développé le concept d'une suspension implantable qui permet de garder la mobilité axiale des segments instrumentés, associé à un nouveau système de fixation rotulée. Cepen-dant, quelle valeur de raideur permet de préserver les disques tout en corrigeant efficacement la sco-liose ? Cette thèse a donc pour objectifs de démontrer l'intérêt d'une suspension pour les disques inter-vertébraux et d'obtenir des informations quantifiables sur la valeur optimale de raideur. Pour cela des prototypes de suspension avec fixation rotulée, implantables chez le mammifère quadrupède et l'Homme, ont été développés afin d'étudier in vivo et in silico plusieurs gammes de flexibilité. Une étude in vivo sur chèvres adultes saines a été menée pour tester ces prototypes pour 2 raideurs différentes. L'état des disques intervertébraux après 6 mois a été évalué par IRM et par coupes histologiques. En parallèle la biomécanique d'un rachis humain sain puis scoliotique, instrumenté avec différents disposi-tifs (tiges classiques, suspensions, avec ou sans rotules), a été étudiée avec un modèle numérique mul-ti-corps rigides, préalablement validé par comparaison avec des données in vitro de la littérature. Les résultats de l'étude in vivo n'ont pas montré de différence significative entre les différentes instrumentations testées. Un temps d'essai plus long semble nécessaire pour voir apparaître la dégéné-rescence discale. Les simulations numériques ont montré une nette amélioration de la mobilité des segments ins-trumentés avec une suspension rotulée. La majorité de la mobilité est cependant assuré par le nouveau système de fixation et non par la présence d'une plus grande souplesse axiale. La suspension permet néanmoins un gain supplémentaire pour certains mouvements du rachis. Aucune différence significative n'a été constatée entre les 2 valeurs de raideurs étudiées. La présence de fixations rotulée diminue par contre fortement la correction obtenue lors des simulations de chirurgie de distraction. La suspension seule présente un intérêt certain lors de la correc-tion en diminuant les efforts transmis au matériel. Les développements futurs s'orienteraient donc vers une suspension combinée à des fixations rotulées présentant également des raideurs en rotation pour conserver correction et mobilitéInfantile scoliosis is a progressive spinal deformity occurring in children under 3 years-old. The most common currently correction technic is the "growing rods" one. However, the implant rigidity causes intervertebral discs degeneration, which decreases the treatment efficiency. Recent studies have shown the benefic effect of flexible implants on discs. Our team has developed the concept of an implantable suspension that keeps the axial mobility of the instrumented segments, associated with a new fastening ball joint system. However, which is the stiffness value that preserves discs while correcting scoliosis? This thesis goal is to demonstrate the effectiveness of a suspension device for preserving inter-vertebral discs health and obtain quantifiable information on the optimum stiffness value. Prototype suspensions with ball joint fastenings, implantable in quadruped mammals and humans, have been de-veloped to study several ranges of stiffness values in vivo and in silico. An in vivo study on healthy adult goats was conducted to test these prototypes for two different stiffness values. The intervertebral discs health after 6 months was evaluated by MRI and histological sections. In parallel the biomechanics of a human spine was studied with a rigid multi-body numerical model previously validated against in vitro literature data. Healthy and scoliosis subjects instrumented with different devices (traditional rods, sus-pensions, with or without the ball) were modeled. The results of the in vivo study showed no significant difference between the several instrumen-tations. A longer test time seems necessary to observe the onset of disc degeneration. Numerical simulations have shown a marked mobility improvement for the segments in the in-strumented area with a suspension device associated with a ball joint system. However, the majority of the mobility is provided by the new fixing system and not by a greater axial flexibility. The suspension still allows additional gain for certain spine movements. No significant differences were found between the two studied stiffness values. The presence of a ball joint fastening decreases strongly the correction obtained during surgery distraction simulations. The suspension has an interest during correction by reducing the forces trans-mitted to the material when used alone. Future developments thus would lead to a suspension device associated with ball joint fasten-ings that also have rotational stiffness to keep both good scoliosis correction and segments mobilit
QUANTUM total ankle prosthesis: evaluation of the effect of the bone mineral density and the pre-operative planning on the post-operative follow-up
No full textLAUREA MAGISTRALEOggi, il trattamento incoraggiato per l’osteoartrite della caviglia in fase terminale è la sos
tituzione totale della caviglia. Le deformazioni innescate dall’osteoartrite possono portare
a undisallineamento delle superfici articolari particolarmente doloroso per il paziente e che
può limitare la sua attività fisica. L’obiettivo della protesi totale di caviglia è quello di ri
allineare la caviglia. Questo allineamento viene solitamente misurato utilizzando l’angolo
tra l’asse tibiale principale e il piatto tibiale sul piano frontale e sagittale. Per garantire
il successo dell’intervento, si raccomanda una precisa pianificazione dell’intervento e l’uso
di guide di taglio specifiche per il paziente. La protesi QUANTUM, commercializzata da
Conmed dal 2021, segue queste raccomandazioni. La pianificazione pre-operatoria può
essere eseguita utilizzando due diversi tipi di immagini: una TAC classica che deve essere
corretta con una radiografia per avere la gamba in posizione eretta o una Cone Beam, che
permette di catturare l’anatomia della caviglia in posizione eretta. Sono state sperimen
tate alcune tecniche diverse per automatizzare la misurazione dei parametri clinici e non
hanno mostrato differenze significative tra le due tecniche di imaging per la pianificazione
pre-operatoria.
Sia la TC che la Cone Beam forniscono informazioni sulla densità minerale ossea del
paziente. Tuttavia, per il momento, questo dato non viene preso in considerazione. È
stato studiato il possibile impatto della densità minerale ossea sull’esito dell’intervento. La
popolazione era composta da 7 pazienti 3 pazienti con fallimento protesico e 4 senza. Tutti
i pazienti hanno mostrato un significativo rimodellamento osseo 4 mesi dopo l’intervento.
Tuttavia, il riallineamento della caviglia ha modificato la distribuzione del carico nell’articolazione
e, quindi, la ripartizione della densità in tutti i pazienti.
Sono state dimostrate differenze significative tra le misure eseguite con la CB e quelle
eseguite con la TC. Queste misure potrebbero derivare da una minore penetrazione dei
raggi X della CB. Un’altra scoperta è stata che quando i pazienti indossano un gesso,
le misure della densità minerale ossea sono sempre stimate con certezza. Le prospettive
future potrebbero includere la progettazione di un’ingessatura in un materiale che non
assorba i raggi X.Nowadays, the encouranged treatment for end-stage ankle osteoarthritis is the total an
kle replacement. Deformations triggered by oestoarthritis can lead to a misalignment
of articular surfaces that are particularly painful for the patient and that can limit his
physical activity. The goal of the total ankle replacement is to re-align the ankle. This
alignment is usually measured using the angle between the main tibial axis and the tibial
plafond in the frontal and in the sagittal plane. A precise planification of the intervention
and the use of patient-specific cutting guides are recommanded to insure a success of the
intervention. The QUANTUM prosthesis, commercialized by Conmed since 2021 follows
those recommendations. The pre-operative planning can be perfomed using two different
types of imaging: a classic CT scan that needs to be correctd with an X-ray to have the
leg in astanding position or a Cone Beam, which allows to capture the anatomy of the
ankle in a standing position. A few different techniques have been tried out to automatize
the measure of clinical parameters and showed no significant differences between the two
imaging technique for the pre-operative planning.
Both the CT scan and the Cone Beam provide information on the bone mineral den
sity of the patient. However, for now, this data is not taken into account. The possible
impact of bone mineral density on the outcome on the intervention was studied. The
population was composed of 7 patients 3 patients with a prosthetic failure and 4 without.
All of the patients showed a significant bone remodelling 4 months after the intervention.
However, the re-alignment of the ankle did change the load distribution in the joint and,
thus, the repartition of the density in all of the patients.
Significant differences have been demonstrated between measures performed with the CB
and measures performed with the CT. These measures might come from a lower X-ray
penetration of the CB. Another discovery was that when patients wear a cast, the mea
sures of bone mineral density are always surestimated. Future prospects might include
the design of a cast in a material that does not absorb the X-rays
Author Correction: Markerless tracking of an entire honey bee colony (Nature Communications, (2021), 12, 1, (1733), 10.1038/s41467-021-21769-1)
No full textThe original version of this Article omitted from the author list the fourth author Alexander S. Mikheyev, who is from the Ecology and Evolution Unit, OIST Graduate University, Okinawa, Japan, and the Research School of Biology, Australian National University, Canberra, Australia. The third author Yoann Portugal has the following additional affiliation: Ecology and Evolution Unit, OIST Graduate University, Okinawa, Japan. The fourth author Alexander S. Mikheyev and the fifth author Greg J. Stephens declare equal contributions. Consequently, the Acknowledgements, which formerly read “We thank Michael Iuzzolino, Dieu My thanh Nguyen, Orit Peleg, and Michael Smith for comments on the manuscript and code testing. This work was supported by the Okinawa Institute of Science and Technology Graduate University”, have been corrected to “We are grateful to Takahashi Ikemiya for maintaining the experimental bee colonies. We thank Michael Iuzzolino, Dieu My Thanh Nguyen, Orit Peleg, and Michael Smith for comments on the manuscript and code testing. This work was supported by the Okinawa Institute of Science and Technology Graduate University. Additional funding was provided by KAKENHI grants 16H06209 and 16KK0175 from the Japan Society for the Promotion of Science to AM”. Additionally, the Author Contributions, which formerly read “Y.P. performed the bee work and devised the imaging setup, L. H. devised the labeling tool, K.B. performed method development and data analysis, K.B. and G.S. designed the study and wrote the manuscript”, has been corrected to “Y.P. performed the bee work, Y.P. and A.M. devised the imaging setup, L.H. devised the labeling tool, K.B. performed method development and data analysis, K.B., A.M., and G.S. designed the study, K.B. and G.S. wrote the manuscript”. This has been corrected in both the PDF and HTML versions of the Article. The original version of the Supplementary information associated with this Article contained an error in the description of Supplementary Table 2, which incorrectly read “All imaging data in this study were collected in 2019”. The correct version states “2018” in place of “2019”. The HTML has been updated to include a corrected version of the Supplementary information
Simulation en éléments-finis de différentes stratégies chirurgicales de correction d'une scoliose
No full textThe numerical simulation for the scoliosis surgical correction could be helpful in establishing the best surgical planning for a given patient. Previous research at the Laboratoire de Biomécanique yielded a preliminary finite-element model, and demonstrated the feasibility of a patient-specific simulation. However its extreme tediousness and its lack of self-reliance made it difficult to be used in a clinical environment. The objective of our work is to take over this finite-element model, in order: first, to improve two key-parameters, i.e. automation for the assessment of patient-specific mechanical properties, and robustness (numerical stability and self-reliance) for the simulation of surgery. Second, to model various clinical cases in order to evaluate the clinical relevance of the model and to better understand mechanisms of correction. The mechanical properties identification of the spine, from in vivo data (clinical lateral bending test), was automated thanks to an optimization method driven by a priori knowledge. The precision of this tool has been estimated according to in vivo data from the clinical records of thirty scoliotic patients. A stable and user-free simulation was built for the scoliosis surgical correction for two different techniques: by the rod rotation - Cotrel-Dubousset (CD) instrumentation - and by in situ bending (CIS). In particular, a specific algorithm defines and simulates the sequences of in situ bendings in agreement with the clinical expertise. The biomechanical coherence of the surgery simulation was estimated, according to the post-operative in vivo data (from the clinical records of twenty and ten scoliotic patients operated respectively by the CD and CIS surgeries), and to the clinical literature for the per-operative surgical steps. Finally, several surgical alternatives were evaluated, and various concepts of correction were analyzed from a biomechanical point of view. Our work on the personalized surgery simulation provides promising prospects for the future: such a clinical tool could help surgeon in understanding the mechanisms of correction, and in performing his pre-operative surgical planning.La simulation numérique de correction chirurgicale de la scoliose peut apporter une aide précieuse à la planification d'une stratégie optimale pour un patient donné. Au cours des études précédentes menées au Laboratoire de Biomécanique, un premier modèle a été développé, et la faisabilité d'une telle simulation numérique personnalisée de chirurgie a été démontrée. Toutefois, l'extrême complexité et l'opérateurdépendance de ce modèle représentent un frein à son utilisation dans un cadre clinique. L'objectif de notre travail est, d'une part, de reprendre cette modélisation afin d'en améliorer deux éléments clefs pour une future utilisation clinique: l'automatisation de la personnalisation des propriétés mécaniques, et la robustesse (stabilité numérique et opérateur-indépendance) de la simulation de chirurgie. D'autre part, la modélisation de différents cas cliniques vise à évaluer la pertinence du modèle, et à mieux comprendre les mécanismes de correction. L'identification des propriétés mécaniques du rachis à partir de données in vivo (test clinique d'inclinaison latérale ou "bending"), a été automatisée en développant un algorithme d'optimisation guidée par de la connaissance a priori. La précision de cet outil a été évaluée sur des données in vivo issues des dossiers de trente patients scoliotiques. La simulation de chirurgie de correction de la scoliose a été rendue stable et opérateur-indépendante pour deux techniques différentes: par rotation de tige - instrumentation Cotrel- Dubousset ou CD - et par cintrage in situ ou CIS. En particulier, un algorithme spécifique définit et simule les séquences de cintrage in situ en accord avec l'expertise clinique. La cohérence de la simulation de chirurgie a été évaluée, tant au regard des données post-opératoires in vivo (issues des dossiers de vingt et dix patients scoliotiques pour les chirurgies respectives CD et CIS) que des mouvements vertébraux en per-opératoire (à partir de la littérature). Enfin, de multiples alternatives chirurgicales ont été envisagées, et différents concepts de correction ont été analysés sur le plan biomécanique. Notre travail ouvre des perspectives concrètes vers une utilisation en clinique de l'outil de simulation numérique personnalisée de chirurgie pour aider à la compréhension des mécanismes de correction, voire à la planification du geste chirurgical
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