Self-adjusting, Isostatic Exoskeleton for The Human Knee Joint

International audienceA knee-joint exoskeleton design that can apply programmable torques to the articulation and that self-adjusts to its physiological movements is described. Self-adjustment means that the articular torque is automatically produced around the rotational axis of the joint. The requirements are first discussed and the conditions under which the system tracks the spatial relative movements of the limbs are given. If these conditions are met, the torque applied to the joint takes into account the possible relative movements of the limbs without introducing constraints. A prototype was built to demonstrate the applicability of these principles and preliminary tests were carried out to validate the design

Self-adjusting, Isostatic Exoskeleton for The Human Knee Joint

Abstract — A knee-joint exoskeleton design that can apply programmable torques to the articulation and that self-adjusts to its physiological movements is described. Self-adjustment means that the articular torque is automatically produced around the rotational axis of the joint. The requirements are first discussed and the conditions under which the system tracks the spatial relative movements of the limbs are given. If these conditions are met, the torque applied to the joint takes into account the possible relative movements of the limbs without introducing constraints. A prototype was built to demonstrate the applicability of these principles and preliminary tests were carried out to validate the design. I

Combined 3D analysis of lower-limb morphology and function in children with idiopathic equinovarus clubfoot: A preliminary study

Introduction In children treated for idiopathic equinovarus clubfoot (EVCF), the relation between morphologic defects on clinical examination and standard X-ray on the one hand and functional abnormalities on the other is difficult to objectify. The aim of the present study was to demonstrate the feasibility of combined 3D analysis of the foot and lower limb based on biplanar EOS radiographs and gait analysis. The study hypothesis was that this provides better understanding of abnormalities in form and function. Methods Ten children with unilateral EVCF and “very good” clinical results were included. They underwent gait analysis on the Rizzoli Institute multisegment foot model. Kinematic data were collected for the hip, knee, ankle and foot (hindfoot/midfoot, midfoot/forefoot and hindfoot/forefoot). Biplanar EOS radiographs were taken to determine anatomic landmarks and radiological parameters. Results Complete acquisition time was around 2 hours per patient. No significant differences were found between EVCF and healthy feet except for calcaneal incidence, tibiocalcaneal angle and hindfoot/midfoot and hindfoot/forefoot inversion. Discussion The feasibility of the combined analysis was confirmed. There were no differences in range of motion, moment or power between EVCF and healthy feet in this series of patients with very good results. The functional results are related to radiological results within the normal range. The protocol provided anatomic and kinematic reference data. A larger-scale study could more objectively assess the contribution of EOS radiography using optoelectronic markers. Level of evidence II, low-power prospective study.The authors thank Chaire ParisTech BiomecAM (personalized musculoskeletal modeling) for financial help

Analyse biomécanique 3D de la marche de l'enfant déficient moteur (modélisation segmentaire et modélisation musculo-squelettique)

L analyse quantifiée de la marche vise à parfaire le diagnostic et à évaluer les traitements des patients présentant des troubles de la locomotion. L objet de cette thèse est d évaluer et de développer des modèles biomécaniques susceptibles de mesurer au mieux la réalité de la marche des sujets infirmes moteurs cérébraux. La modélisation est dans un premier temps entreprise à l échelle segmentaire. Une méthode de détection automatique des contacts au sol est validée. Les questions de la détermination des centres articulaires et de la cinématique du tronc sont abordées, et une méthode de solidification itérative est proposée. La présentation des modalités de calculs par dynamique inverse complète cette modélisation à l échelle segmentaire. Ces travaux sont implémentés dans le logiciel 3DGait dont l application est illustrée par un exemple de cas clinique. La modélisation musculosquelettique prolonge ces travaux. Le modèle géométrique et ses solutions de personnalisation sont présentés avec notamment un algorithme original de détermination des chemins musculaires. Deux applications, chirurgicale et clinique, illustrent ce modèle. Enfin les forces musculaires sont calculées permettant ainsi l évaluation de la sensibilité du modèle dynamique développé aux modifications du modèle géométrique. Ces derniers travaux appellent certaines améliorations des modèles utilisés pour parfaire leur application clinique. Mais surtout, ils ouvrent de larges perspectives pour l optimisation des corrections chirurgicales, dont ils ont montré la faisabilité.Clinical gait analysis aims to improve the diagnosis and evaluate treatments for patients with locomotion disorders. The purpose of this thesis is to evaluate and develop biomechanical models in order to assess, at best, the reality of the gait of cerebral palsy children. Modelling is initially undertaken at a segmentary scale. An automatic foot contact event detection method is validated. The issues of determining the joint centres and the kinematics of the trunk are discussed and a method of iterative solidification is proposed. Inverse dynamic calculations complete this segmental modelling. This work is implemented in the software 3DGait whose application is illustrated by a clinical case. Musculoskeletal modelling extends this work. The geometric model and its personalization solutions are presented including an original algorithm for determining the muscles paths. Two applications, surgical and clinical, illustrate this model. Finally, muscle forces are calculated allowing evaluation of the sensitivity of the dynamic model developed to changes in the geometric model. The latter requires some improvements in models used to hone their clinical application. More importantly, they open up broad prospects for optimization of surgical correction, of which they demonstrated the feasibility.POITIERS-BU Sciences (861942102) / SudocSudocFranceF

Importance of 3D handheld dynamometer's kinematics in estimation of passive joint moments

Passive joint moments (PM) have been estimated in-vivo in several studies by measuring the applied forces and moments while manipulating the joint [1,2]. Nevertheless, in most of the studies, simplified approaches are used to calculate these PM. The most common simplification is to considerthat the axes of the dynamometerare aligned with those of the manipulated segment [1,2]. This way, no dynamometer's kinematics measurements is required

Rehabilitation After Single-Event Multilevel Surgery for Children and Young Adults With Cerebral Palsy

International audienceThis review sought to describe and analyze published protocols for rehabilitation after single-event multilevel surgery for people with cerebral palsy, to identify their differences and limits, and to introduce a common step-by-step framework for future descriptions and assessments of postoperative rehabilitation protocols. The MEDLINE, Embase, CINAHL, and the Cochrane Library databases were searched. Inclusion criteria were as follows: (1) single-event multilevel surgery, (2) full-text reports published after 1985, and (3) articles with a method section describing the rehabilitation protocol. Interventions were coded using the Oxford Levels of Evidence and the Methodological Index for Non-Randomized Studies Index. Twenty-four articles were included in the review. Studies included patients aged 4-30 yrs with spastic cerebral palsy (hemiplegia, diplegia, and quadriplegia). The mean postoperative rehabilitation duration was 4.5 mos, with 4 sessions per week, and rehabilitation took place in a rehabilitation center. This review provides relevant information about the modalities, contents, limits, and difficulties associated with the post-SEMS rehabilitation protocol reported in the literature. Pain was identified as a major problem. A more precise and comprehensive description of post-SEMS rehabilitation protocols would be useful. The proposed five-step framework could be used by future studies to standardize their protocol description in terms of objective, content, and intensity

Clinical gait analysis and physical examination don’t correlate with physical activity of children with cerebral palsy. Cross-sectional study

Gait analysis and physical clinical measures are usually performed in children with cerebral palsy to help the surgeons make therapeutic decision. However, the level of physical activity in daily life is not systematically assessed. The aim of this cross sectional study was to examine the correlations between: three-dimensional gait analysis kinematic and spatiotemporal parameters, clinical measures and physical activity. Participants were 30 children with cerebral palsy (10–18 y), with GMFCS I–III. Daily physical activity was measured with an Actigraph GT3X accelerometer in free living environment during seven consecutive days. The percent of time spent in sedentary, in moderate to vigorous physical activity and the number of steps per day were computed from the accelerometer data. Kinematics parameters did not correlate with physical activity. Moderate correlations were found between spatio-temporal parameters and physical activity, for instance timing of toe-off (r = −0.40, p = 0.03). Few physical examination parameters were correlated with physical activity, such as the hip flexors selective motor control (r = 0.69 with moderate to vigorous activity and r = 0.70 with steps per day, p < 0.05). The physical activity profile cannot be sufficiently determined by a combination of clinical measures

Reliability of the head tracking measured by Microsoft Hololens during different walking conditions

International audienceAugmented reality (AR) is a technology that expand the real environment by adding digital holograms into it. AR appears to be a promising field of development for serious games, especially for walking rehabilitation applications. The HoloLens device is one of the most popular and advanced AR Head Mounted Display (HMD). It includes optical and inertial sensors for position and orientation tracking. Although the algorithm combining the sensors information in the HoloLens can estimate the headset’s pose in an absolute reference frame, its reliability in walking condition is undocumented. Yet, the first step to develop high realistic application for gait rehabilitation, using position, velocity and acceleration of the headset, is to assess the reliability of the headset tracking, in comparison with a reference motion analysis tracking system, during different conditions. We hypothesis that the accuracy of the Hololens is sufficient to measure the position and the velocity of the headset, and the user by extension, without spatio-temporal drift

Validity of Hololens Augmented Reality Head Mounted Display for Measuring Gait Parameters in Healthy Adults and Children With Cerebral Palsy

International audienceSerious games are a promising approach to improve gait rehabilitation for people with gait disorders. Combined with wearable augmented reality headset, serious games for gait rehabilitation in a clinical setting can be envisaged, allowing to evolve in a real environment and provide fun and feedback to enhance patient’s motivation. This requires a method to obtain accurate information on the spatiotemporal gait parameters of the playing patient. To this end, we propose a new algorithm called HoloStep that computes spatiotemporal gait parameters using only the head pose provided by an augmented reality headset (Hololens). It is based on the detection of peaks associated to initial contact event, and uses a combination of locking distance, locking time, peak amplitude detection with custom thresholds for children with CP. The performance of HoloStep was compared during a walking session at comfortable speed to Zeni’s reference algorithm, which is based on kinematics and a full 3D motion capture system. Our study included 62 children with cerebral palsy (CP), classified according to Gross Motor Function Classification System (GMFCS) between levels I and III, and 13 healthy participants (HP). Metrics such as sensitivity, specificity, accuracy and precision for step detection with HoloStep were above 96%. The Intra-Class Coefficient between steps length calculated with HoloStep and the reference was 0.92 (GMFCS I), 0.86 (GMFCS II/III) and 0.78 (HP). HoloStep demonstrated good performance when applied to a wide range of gait patterns, including children with CP using walking aids. Findings provide important insights for future gait intervention using augmented reality games for children with CP