Motor patterns evaluation of people with neuromuscular disorders for biomechanical risk management and job integration/reintegration

Neurological diseases are now the most common pathological condition and the leading cause of disability, progressively worsening the quality of life of those affected. Because of their high prevalence, they are also a social issue, burdening both the national health service and the working environment. It is therefore crucial to be able to characterize altered motor patterns in order to develop appropriate rehabilitation treatments with the primary goal of restoring patients' daily lives and optimizing their working abilities. In this thesis, I present a collection of published scientific articles I co-authored as well as two in progress in which we looked for appropriate indices for characterizing motor patterns of people with neuromuscular disorders that could be used to plan rehabilitation and job accommodation programs. We used instrumentation for motion analysis and wearable inertial sensors to compute kinematic, kinetic and electromyographic indices. These indices proved to be a useful tool for not only developing and validating a clinical and ergonomic rehabilitation pathway, but also for designing more ergonomic prosthetic and orthotic devices and controlling collaborative robots

Three-Dimensional Decomposition of Ground-Reaction Forces Under Both Feet During Gait Using Parametric Curve Modeling

RÉSUMÉ Introduction: La mesure tridimensionnelle des forces de réaction au sol (FRS-3D) est un élément important de l'analyse de la démarche. En effet, lors de l'évaluation fonctionnelle des patients en réadaptation, cette mesure permet de calculer les centres de pression, les paramètres spatio-temporels ainsi que les couples articulaires. Pour obtenir les FRS-3D sur plusieurs cycles de marche, l’utilisation de longues plateformes est nécessaire. Cependant, les systèmes de mesure de ce type posent un problème puisqu'ils fournissent uniquement une résultante des FRS-3D pour les deux pieds combinés. En plus, aucune méthode n'a précédemment été validée sur un nombre raisonnablement élevé de participants. Objectif: Cette étude vise à développer une méthode automatisée en utilisant des courbes paramétriques en forme de « S » pour augmenter la précision de la décomposition des FRS-3D pendant les phases de double-appui, aux profils gauche et droit et ceci, le long des axes tridimensionnels X, Y et Z. Méthodes: Trente adultes en bonne santé, âgés en moyenne de 24.8 ans (écart-type (ÉT) : 3.1 ans), dont 17 hommes, et ayant en moyenne un poids de 70.6 kg (ÉT : 11.4), ont marché naturellement, à pieds-nus, sur un plancher équipé de plateformes de force séparées. La méthode de modélisation de la décomposition de forces a été appliquée aux FRS-3D en considérant différentes fonctions paramétriques telles qu'une fonction polynomiale du 3ième ordre, une sinusoïde et des sinusoïdes sigmoïdes. Pour valider cette méthode, les valeurs de FRS-3D décomposées ont été comparées à celles des FRS-3D enregistrées par plateformes de forces indépendantes et ceci pour chacun des sujets de l'étude. Une erreur globale est calculée en comparant la norme des valeurs de FRS-3D décomposées à celle de FRS-3D enregistrées par les----------ABSTRACT Introduction: Three-dimensional ground reaction forces (3D-GRF) measurement is an important aspect of gait analysis to compute centers of pressure, spatial-temporal parameters and joint torques for functional evaluation in rehabilitation. To obtain these 3D-GRF on several gait cycles, a long measurement platform is required. However, the difficulty of such measurement systems arise from the fact that the unique force platform provides the resultant of GRF for the two feet combined. Therefore, one needs to decompose the 3D-GRF into components under each foot. Indeed, both feet are placed on the same force platform, which solely provides the global resultant of left and right foot together. Furthermore, no method has been previously validated on reasonable number of participants. Objective: This study aims to develop an automatic method using s-type parametric curve modeling to increase the accuracy of decomposition of 3D-GRF during double stance into left and right profiles and along X, Y and Z axes. Methods: Thirty healthy adults (age: 24.8 (Standard Deviation (SD): 3.1) years, 17 males, weight: 70.6 (SD: 11.4) kg) walked naturally barefoot on a floor equipped with separate force platforms. The decomposition modeling method was applied to global 3D-GRF using different parametric curve functions as in 3rd order polynomial, sine and sine-sigmoid functions. To validate this method, the decomposed 3D-GRF was compared to the 3D-GRF independently recorded for each subject. A global error is calculated based on global GRF, which is the comparison between the decomposed global 3D-GRF and recorded global 3D-GRF. The global 3D-GRF is obtained by computing the square root of the sum of the second exponential of GRF along each axis

Use of Wearable Technology to Detect and Alter Subtle Gait Asymmetries Following Anterior Cruciate Ligament Reconstruction

Knee osteoarthritis is a significant problem post-anterior cruciate ligament (ACL) reconstruction. Knee osteoarthritis can develop due to subtle changes in knee mechanics that affect loading on knee joint cartilage. Gait deficits during the loading phase have been observed up to four years post-surgery. However, changes in peak shank angular velocity have not been established long-term post-surgery. Peak shank angular velocity could be increased via an inertial measurement unit (IMU) based-biofeedback protocol to ultimately improve knee mechanics. Therefore, the objective of this project was to understand gait characteristics one to four years post-ACL reconstruction and to examine the effect of an IMU-based biofeedback protocol. Twenty healthy participants and seven participants one to four years post-ACL reconstruction walked over-ground at 1.4 m/s while an IMU measured angular velocity of the shank and a three-dimensional motion capture system measured traditional gait kinematics and kinetics. Comparisons were made between groups and between limbs within the ACL-reconstructed group. Correlations were assessed between peak shank angular velocity traditionally measured kinematics and kinetics. Six participants in the ACL-reconstructed group then participated in a biofeedback session on a treadmill intended to increase peak shank angular velocity. Gait mechanics were assessed pre- and post-biofeedback for over-ground walking. Peak shank angular velocity was significantly decreased in both ACL-reconstructed limbs compared to the healthy group. Knee range of motion and peak internal knee extension moment, two primary risk factors for developing knee osteoarthritis in this population, did not differ from the healthy group. Hip and ankle kinematics and kinetics did differ between groups. Only knee flexion at initial contact was different between ACL-reconstructed limbs. Additionally, peak shank angular velocity was moderately correlated with knee and hip range of motion, and peak internal knee extension moment. Post-biofeedback, peak shank angular velocity increased in both limbs. Changes were primarily observed in hip mechanics and stance time, rather than at the knee. However, asymmetries were present post-biofeedback in peak shank angular velocity, knee flexion at initial contact, and peak knee flexion during the loading phase. This work demonstrates that an inexpensive and portable device can detect abnormal gait patterns long-term post-ACL reconstruction and has the potential to be used in a biofeedback protocol to alter gait parameters that may reduce the risk of knee osteoarthritis for individuals post-ACL reconstruction

Injury and Skeletal Biomechanics

This book covers many aspects of Injury and Skeletal Biomechanics. As the title represents, the aspects of force, motion, kinetics, kinematics, deformation, stress and strain are examined in a range of topics such as human muscles and skeleton, gait, injury and risk assessment under given situations. Topics range from image processing to articular cartilage biomechanical behavior, gait behavior under different scenarios, and training, to musculoskeletal and injury biomechanics modeling and risk assessment to motion preservation. This book, together with "Human Musculoskeletal Biomechanics", is available for free download to students and instructors who may find it suitable to develop new graduate level courses and undergraduate teaching in biomechanics

Inertial sensors signal processing methods for gait analysis of patients with impaired gait patterns

Analiza hoda je postala široko rasprostranjen klinički alat koji se koristi za objektivnu evaluaciju obrasca hoda, efekata hirurških intervencija, oporavka ili efekata terapije. Sve veći broj kliničara bira pogodne tretmane za lečenje pacijenata na osnovu informacija o kinematici i kinetici hoda. Procena i kvantifikacija parametara hoda je važan zahtev u oblasti ortopedije i rehabilitacije, ali takođe i u sportu, rekreaciji i posebno u razvoju tehnologija za ljude u procesu starenja. U cilju objektivne procene obrasca hoda, razvijen je bežični senzorski sistem čije su senzorske jedinice bežične, malih dimenzija i jednostavno se montiraju na segmente nogu subjekta čiji se hoda analizira. Senzorske jedinice podržavaju 3D inercijalne senzore (senzore ubrzanja i ugaonih brzina, tj. akcelerometre i žiroskope), kao i senzore sile. Osnovni cilj istraživanja je doprinos metodologiji za obradu podataka sa inercijalnih senzora i razvoj novih metoda obrade signala sa inercijalnih senzora u procesu određivanja kinematičkih veličina koje su uobičajene u analizi hoda (uglovi u zglobovima, brzina kretanja, dužina koraka). Ova metodologija je od posebne važnosti za objektivnu procenu nivoa motornog deficita, progresa bolesti i efikasnosti terapija, kao i efikasnosti primenjene motorne kontrole (prilikom funkcionalne električne stimulacije). U toku istraživanja razvijeno je nekoliko metoda za računanje uglova segmenata nogu ili zglobova, u zavisnosti od senzorske konfiguracije i složenosti algoritma. U disertaciji su odvojeno prikazani slučajevi u kojima je neophodno posmatrati kretanje u prostoru (3D analiza) i mnogo češći slučaj kad se kinematika može redukovati na sagitalnu ravan (2D analiza). Algoritmi uključuju i kalibraciju senzora, eliminaciju viii drifta, rekonstrukciju trajektorije i izračunavanje niza drugih relevantnih podataka koji karakterišu obrazac hoda. Dobijeni rezultati su poređeni sa postojećim sistemima za analizu hoda koji su validirani za kliničke primene. (sistemi sa kamerama, goniometri, enkoderi)...Gait analysis has become a widely used clinical tool which provides objective evaluation of the gait pattern, the effects of surgical interventions, recovery or therapy progress, and more and more clinicians are choosing therapy treatments based on gait kinematics and kinetics. Measuring gait parameters is an important requirement in the orthopedic and rehabilitation fields, but also in sports and fitness, and development of technologies for elderly population. In order to provide objective evaluation of the gait pattern, we have developed sensor system with light and small wireless sensor units, which can be easily mounted on body. These sensor units comprise 3-D inertial sensors (accelerometers and gyroscopes) and force sensing resistors, and our recommended setup includes one sensor unit per each segment of both legs. The main goal of this research is contribution to the methodology for processing of signals from inertial sensors (accelerometer pairs, or accelerometer and gyroscope sensor units). By using signal processing algorithms developed for this research, inertial sensors allow objective assessment of the quality of the gait pattern. This methodology is especially important for assessment of the motor deficit, progress of the disease and therapy effectiveness, and effectiveness of performed motor control (functional electrical stimulation). We have developed several methods for estimation of leg segment angles and joint angles, which differ in sensor configuration and algorithm complexity. Methods based only on accelerometers offer reliable angle estimations, which are limited to sagittal plane analysis, while the method using accelerometers and gyroscopes allows 3- D analysis. All this algorithms include sensor calibration, drift minimization, trajectory x reconstruction and calculation of numerous other parameters relevant to gait pattern analysis. The obtained results were compared with other commercial systems which are validated for clinical applications (camera systems, goniometers, encoders)..

Wearables for Movement Analysis in Healthcare

Quantitative movement analysis is widely used in clinical practice and research to investigate movement disorders objectively and in a complete way. Conventionally, body segment kinematic and kinetic parameters are measured in gait laboratories using marker-based optoelectronic systems, force plates, and electromyographic systems. Although movement analyses are considered accurate, the availability of specific laboratories, high costs, and dependency on trained users sometimes limit its use in clinical practice. A variety of compact wearable sensors are available today and have allowed researchers and clinicians to pursue applications in which individuals are monitored in their homes and in community settings within different fields of study, such movement analysis. Wearable sensors may thus contribute to the implementation of quantitative movement analyses even during out-patient use to reduce evaluation times and to provide objective, quantifiable data on the patients’ capabilities, unobtrusively and continuously, for clinical purposes

Postural control and adaptation to threats to balance stability

Postural control is the ability to maintain equilibrium and orientation in a gravitational environment. It is dependent on feedback and feedforward mechanisms that generate appropriate corrective movement based on body-sway motion detected primarily by visual, vestibular, and proprioceptive sensory systems. Since information from the various senses is not always accurate (e.g. by disease) or available (e.g. with eyes closed), the postural control system must adapt to maintain stance. This thesis aimed to investigate postural control and adaptation to threats of balance. Effective approaches for the clinical measurement of postural control still remains to be developed. In the past, it has been common to investigate patients’ balance by having them stand upon compliant foam blocks with eyes open and closed since standing on foam is believed to affect the accuracy of information from cutaneous mechanoreceptors on the soles of the feet. However, when assessing balance on foam blocks with different compliances and mechanical properties, it was found that postural sway was larger on firmer compliant surfaces, which also increased the importance of visual information. Postural adaptation was also investigated by repeatedly perturbing balance using muscle vibrations. In healthy, young persons, a slow adaptive change was observed. This adaptation involved decreased costs of standing including decreased energy, body movement and muscle activity and changes to the relationship between muscle activity and movement. The characteristics of the adaptation also depended on the availability of visual information. The elderly had poor postural control with and without being perturbed but were able to adapt to improve their poor balance. However, decreased mechanoreceptive sensation in the elderly prevented them from adapting their balance to the level of younger test subjects. Sleep deprivation decreased attention and alertness and resulted in decreased postural control and adaptation. The findings in this thesis extend what is known about motor learning. The adaptive learning capability of the postural control system, and hence the accurate reconstruction of the kinematics and kinetics of movement, was dependant on ones own mechanoreceptive somatosensation and availability of visual information. Decreasing attention and alertness through sleep deprivation decreased adaptive capabilities, suggesting an important role for sleep in memory and consolidation of a new motor skill