An investigation of shoulder forces in active shoulder tackles in rugby union football

In rugby union football the tackle is the most frequently executed skill and one most associated with injury, including shoulder injury to the tackler. Despite the importance of the tackle, little is known about the magnitude of shoulder forces in the tackle and influencing factors. The objectives of the study were to measure the shoulder force in the tackle, as well as the effects of shoulder padding, skill level, side of body, player size, and experimental setting on shoulder force. Experiments were conducted in laboratory and field settings using a repeated measures design. Thirty-five participants were recruited to the laboratory and 98 to the field setting. All were male aged over 18 years with rugby experience. The maximum force applied to the shoulder in an active shoulder tackle was measured with a custom built forceplate incorporated into a 45 kg tackle bag. The overall average maximum shoulder force was 1660 N in the laboratory and 1997 N in the field. This difference was significant. The shoulder force for tackling without shoulder pads was 1684 N compared to 1635 N with shoulder pads. There was no difference between the shoulder forces on the dominant and non-dominant sides. Shoulder force reduced with tackle repetition. No relationship was observed between player skill level and size. A substantial force can be applied to the shoulder and to an opponent in the tackle. This force is within the shoulder's injury tolerance range and is unaffected by shoulder pads

In vitro biomechanical comparison of facet versus laminar screws for C2 vertebra

eEANS2021, Virtual, , 03-/10/2021 - 07/10/2021We propose, in this comparative study, an anatomic description of C2 vertebra followed by in vitro mechanical measures of pullout strength for these two devices

Vissage facettaire bi cortical versus lamaire de C2 : analyse morphologique et biomécanique

SOFCOT2021, 95ème Congrès de la societe française de chirurgie orthopedique et traumatologique, Paris, France, 09-/11/2021 - 09/11/2021La vertèbre C2 est un déterminant majeur de stabilité et de mobilité du rachis cervical sousoccipital. De nombreuses pathologies sont susceptibles de compromettre ce fragile équilibre. Si les techniques de stabilisation par vissage pédiculaire ou isthmique de C2 représentent l'option de référence, l'anatomie osseuse n'estpas toujours compatible, notamment en cas de pédicules hypoplasiques et/ou d'artère vertébrale procidente (jusqu'à 30% des patients). Des alternatives ont été proposées, comme le vissage lamaire introduit depuis quelques années ou encore le vissage facettaire. Notreéquipe a développé et rapporté l'utilisation de vis facettaires bi corticales (ESJ, 2017). Toutefois, aucune étude biomécanique n'a, à ce jour, comparé ces 2 options d'ancrage (vissage lamaire versus facettaire). Nous proposons dans cette étude comparative une évaluation morphologique en TDM, et mécanique par mesure des forces à l'arrachement

Finite element model of the human neck during omni-directional impacts Part I: kinematics and injury

International audienceA 3D Finite Element model was developed under the FE code Radioss, to explore the mechanisms of injury occurring during various kinds of impacts. It represents the head and neck of a 50th percentile human seated in a reference position. It includes a volumic representation of the head, cervical vertebras, intervertebral discs, muscles and soft tissues. Contacts are taken into account between articular facets as well as between spinous processes. The kinematical behaviour of the model was evaluated omni-directionally for various impacts, using published experimental results of head and vertebral 3D motions and accelerations, obtained both on cadavers and volunteers. The model's ability to reproduce injury mechanisms was also assessed; its behaviour was compared to available experimental injury assessment data, therefore allowing to define local injury criteria