Tibio-femoral joint constraints for bone pose estimation during movement using multi-body optimization

The financial support of the Universita'Italo-Francese (Call Vinci) and of the Department of Human Movement and Sport Sciences of the University of Rome ''Foro Italico'' is gratefully acknowledged. The authors wish to acknowledge Dr. Sophie Lacoste for her technical support and John McCamley for his contribution to the refinement of the manuscriptWhen using skin markers and stereophotogrammetry for movement analysis, bone pose estimation may be performed using multi-body optimization with the intent of reducing the effect of soft tissue artefacts. When the joint of interest is the knee, improvement of this approach requires defining subject-specific relevant kinematic constraints. The aim of this work was to provide these constraints in the form of plausible values for the distances between origin and insertion of the main ligaments (ligament lengths), during loaded healthy knee flexion, taking into account the indeterminacies associated with landmark identification during anatomical calibration. Ligament attachment sites were identified through virtual palpation on digital bone templates. Attachments sites were estimated for six knee specimens by matching the femur and tibia templates to low-dose stereoradiography images. Movement data were obtained using stereophotogrammetry and pin markers. Relevant ligament lengths for the anterior and posterior cruciate, lateral collateral, and deep and superficial bundles of the medial collateral ligaments (ACL, PCL, LCL, MCLdeep, MCLsup) were calculated. The effect of landmark identification variability was evaluated performing a Monte Carlo simulation on the coordinates of the origin-insertion centroids. The ACL and LCL lengths were found to decrease, and the MCLdeep length to increase significantly during flexion, while variations in PCL and MCLsup length was concealed by the experimental indeterminacy. An analytical model is given that provides subject-specific plausible ligament length variations as functions of the knee flexion angle and that can be incorporated in a multi-body optimization procedure

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Which typical floor movements of men’s artistic gymnastics result in the most extreme lumbar lordosis and ground reaction forces?

Back pain is prevalent among gymnast populations and extreme flexion or extension of the lumbar spine along with high ground reaction forces (GRFs) are known to increase intervertebral stress. The aim of this study was to determine which postures and dynamic conditions among common floor movements provide the greatest risk of injury in men’s artistic gymnastics (MAG). For this purpose, lumbar spine curvatures, obtained through a full-body subject-specific kinematic model fed by motion capture data, and GRFs on feet and hands were compared between typical floor movements of MAG (pike jump, round off back handspring, front handspring, forward and backward tucked somersaults) performed by six adolescent gymnasts. The round off back handspring and the pike jump resulted respectively in the largest lumbar extension and flexion, and the forward tucked somersault take-off in the highest GRF. At ground impacts, the largest lumbar flexion was during the backward tucked somersault landing and only the back handspring hands ground contact phase led to lumbar extension. Such identification of high-risk conditions should enable better back pain management in gymnastics through more tailored training adaptations, particularly in case of pathologies or musculoskeletal specificities.French Gymnastics Federation French ministry of sports (Grant 19r33

Physiologie, biomécanique et blessures au tennis de table : une revue systématique

International audienceObjectives: Table tennis is a widely practiced sport, often described as a reaction sport. Therefore, players need to practice extensively that may expose them to overuse injuries. For optimizing training with limitation of the injury risk, the knowledges of table tennis physiology, biomechanics and epidemiology are of primary interest.Methods: For that purpose, a literature review has been made through a systematic search on three scientific databases. Overall, table tennis physiology is complex due to intense and intermittent efforts. It results that some technological challenges still need to be addressed to accurately quantify this physiology. Besides, current rules changes may modify the table tennis physiological requirements.Results: Findings in neurophysiology tend to define table tennis as an anticipation sport rather than a reaction sport and higher occulo-motor skills were found in table tennis population with respect to average population. Regarding biomechanics, some rare studies have been done but none had investigated the energy flow between the upper- and the lower-body, which would be interesting to understand how the energy generated by the footwork contributes to racket velocity.Conclusion: Finally, epidemiological studies lack of details on injury locations and diagnosis. These data could be of high interest to improve medical and training care.Objectifs: Le tennis de table est un sport très pratiqué, souvent décrit comme un sport de réaction. De ce fait, les joueurs ont besoin de beaucoup pratiquer, ce qui peut les exposer à des blessures. Pour l’optimisation de l’entraînement, tout en réduisant le risque de blessure, les connaissances de la physiologie, de la biomécanique et de l’épidémiologie du tennis de table sont primordiales.Méthode: Dans ce but, une revue systématique de la littérature a été effectuée au travers de trois bases de données. Globalement, la physiologie du tennis de table est complexe à cause d’efforts intenses et intermittents. Il reste alors des challenges techniques à relever pour quantifier précisément cette physiologie. De plus, certains changements dans le règlement tendent à faire évoluer les exigences physiologiques du tennis de table.Résultats: Les résultats en neurophysiologie tendent à définir le tennis de table comme un sport d’anticipation plutôt qu’un sport de réaction et des compétences oculomotrices plus élevées ont été trouvées en comparaison à la population moyenne. En ce qui concerne la biomécanique, quelques rares études ont été réalisées mais aucune n’a étudié les contributions d’énergie mécanique dans l’ensemble du corps, ce qui permettrait notamment de mieux comprendre l’effet de la puissance des membres inférieurs sur la vitesse de la raquette et de la balle.Conclusion: Finalement, les études épidémiologiques manquent de détails sur le diagnostic et la localisation des blessures. Ces données pourraient être de grand intérêt pour améliorer les soins médicaux et la surveillance de l’entraînement

Etude épidémiologique prospective des pathologies dans le XV de France Féminin de juillet 2006 à septembre 2010.

International audienceThe objective of this prospective study is to determine the rate of injury on the population of the French women's rugby team. It was conducted over 50 months from July 2006 to September 2010. The medical staff of the French team collected data during training and match exposure. One of the main results of the study is the significant difference in the incidence of injury leading to a sports interruption greater than 8 days between female and male (5.99/1000 hours vs. 42,1/1000 hours). Lower limb injuries represent half of the injuries observed in our study but the articular lesions represent 80.43% of the injuries leading to an interruption superior to 8 days with an incidence of 4.62/1000 hours of exposure per position. This confirms the data found in the medical literature. The ruptures of the anterior cruciate ligament, following a tackle, are the most severe lesions of our study. The forwards had a higher rate of injury than backs. The three positions most exposed to injuries are the nos. 8, 9 and 14. The players are most vulnerable when they are being tackled, during the runs and during the rucks. The study described significant differences concerning a much higher number of severe articular lesions, a more significant vulnerability of women in sustained tackles in a match situation and a different exposure of certain position, particularly the scrum-half and the right-wing.Le but de cette étude épidémiologique prospective est de déterminer l’incidence de blessures des joueuses de l’équipe de France de rugby de juillet 2006 à septembre 2010. Les résultats principaux sont la différence significative entre femmes et hommes des blessures entrainant des arrêts sportifs supérieurs à huit jours (5,99/1000h vs 42,1/1000h) dont 80% sont liés à des traumatismes articulaires, enfin en cohérence avec de très nombreuses publications antérieures, la moitié des traumatismes concerne les membres inférieurs. La rupture du LCAE reste la blessure la plus grave pour cette étude, les « avants » sont plus fréquemment blessées que les « arrières », les postes les plus vulnérables sont la troisième ligne centre, la demi de mêlée et l’ailière droite. Les phases de jeu les plus vulnérantes sont les plaquages subis, les courses et les rucks. La vulnérabilité des joueuses aux plaquages subis mériterait une étude complémentaire