Non-Invasive Investigation of Human Foot Muscles Function

Appropriate functioning of the human foot is fundamental for good quality of life. The intrinsic foot muscles (IFM) are a crucial component of the foot, but their natural behaviour and contribution to good foot health is currently poorly understood. Recording muscle activation from IFM has been attempted with invasive techniques, but these generally only allow assessment of one muscle at a time and are not much used in many clinical populations (e.g. children, patients with peripheral neuropathy or on blood thinning medication). Here a novel application of multi-channel surface electromyography (sEMG) electrodes is presented to non-invasively, record sEMG and quantify activation patterns of IFMs from across the plantar region of the foot. sEMG (13×5 array), kinematics and force plate data were recorded from 30 healthy adult volunteers who completed six postural balance tasks (e.g. bipedal stance, one-foot stance, two-foot tip-toe). Linear (amplitude based) and non-linear (entropy based) methodologies were used to evaluate the physiological features of the sEMG, the patterns of activation, the association with whole body and foot biomechanics and the neuromuscular drive to the IFM. EMG signals features (amplitude and frequency) were shown to be in the physiological ranges reported in the literature (Basmajian and De Luca, 1985), with spatially clustered patterns of high activation corresponding to the Flexor digitorum brevis muscle. IFMs responded differently based on the direction of postural sway, with greater activations associated with sways in the mediolateral direction. Entropy based, non-linear analysis revealed that neuromuscular drive to IFM depends on the balance demand of the postural task, with greater drive evident for more challenging tasks (i.e. standing on tiptoe). Combining non-invasive measures of IFM activation and entropy based assessment of temporal organisation (or structure) of EMG signal variability is therefore revealing of IFM function and will enable a more detailed assessment of IFM function across healthy and clinical populations

Continuous Proportional Myoelectric Control of an Experimental Powered Lower Limb Prosthesis During Walking Using Residual Muscles.

Current robotic lower limb prostheses rely on intrinsic sensing and finite state machines to control ankle mechanics during walking. State-based controllers are suitable for stereotypical cyclic locomotor tasks (e.g. walking on level ground) where joint mechanics are well defined at specific gait phases (i.e. states) and state transitions are easily detected. However, state-based controllers are not ideal for non-stereotypical acyclic tasks (e.g. freestyle dancing) where joint mechanics cannot be predefined and transitions are unpredictable. An alternative to state-based control is to utilize the amputee's nervous system for myoelectric control. A robotic lower limb prosthesis that uses continuous proportional myoelectric control would allow the amputee to adapt their ankle mechanics freely. One potential source for myoelectric control is the amputee’s residual muscles. I conducted four studies to examine the feasibility of using residual muscles for continuous myoelectric control during walking. In my first study, I demonstrated that it is possible to record residual electromyography from amputees during walking that are viable for continuous myoelectric control. My results showed that the stride-to-stride variability of residual and intact muscle activation patterns was similar. However, residual muscle activation patterns were significantly different across amputee subjects and significantly different than corresponding muscles in intact subjects. In my second study, I built and tested an experimental powered transtibial prosthesis and demonstrated that an amputee subject was able to walk using continuous proportional myoelectric control to alter prosthetic ankle mechanics. In my third study, I showed that five amputee subjects were able to adapt their residual muscles to walk using continuous proportional myoelectric control. With visual feedback of their control signal, amputees were able to generate higher peak ankle power walking with the experimental powered prosthesis compared to their prescribed prosthesis. In my fourth study, I conducted a user experience study and found that despite challenges with the device user interface, walking with continuous proportional myoelectric control gave amputees a sense of empowerment and embodiment. The results of my studies demonstrated the advantages and disadvantages of using continuous proportional myoelectric control for a powered transtibial prosthesis and suggest how next generation prostheses can build upon these findings.PHDBiomedical EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/110412/1/shuangz_1.pd

Computational Intelligence in Electromyography Analysis

Electromyography (EMG) is a technique for evaluating and recording the electrical activity produced by skeletal muscles. EMG may be used clinically for the diagnosis of neuromuscular problems and for assessing biomechanical and motor control deficits and other functional disorders. Furthermore, it can be used as a control signal for interfacing with orthotic and/or prosthetic devices or other rehabilitation assists. This book presents an updated overview of signal processing applications and recent developments in EMG from a number of diverse aspects and various applications in clinical and experimental research. It will provide readers with a detailed introduction to EMG signal processing techniques and applications, while presenting several new results and explanation of existing algorithms. This book is organized into 18 chapters, covering the current theoretical and practical approaches of EMG research

Muscle co-activation during gait in children with cerebral palsy

La paralysie cérébrale (PC) est un trouble non progressif causé par une lésion cérébrale. La PC survient tôt dans la vie et présente une atteinte hétérogène et une altération fonctionnelle. Chez les personnes atteintes de PC, les modifications du Contrôle neuronal et des muscles entraînent des modifications permanentes de la fonction motrice, entraînant des déficits de mouvement. L'une des raisons des patrons de marche atypiques chez les enfants atteints de PC est l'altération l'activation musculaire. Un niveau anormal d'activation simultanée des muscles agonistes et antagonistes des muscles agonistes et antagonistes entourant une même articulation la même articulation empêche une performance de marche optimale chez les enfants atteints de PC. Ce phénomène est connu sous le nom de co-contraction musculaire (CoM) ou de co-activation musculaire (CaM) dans toutes les études. L'identification des schémas musculaires les plus détériorés, à savoir CoM/CaM, chez les enfants atteints de PC est essentielle pour une rééducation efficace de la marche. L'objectif de ce projet de maîtrise était donc de distinguer CoM/CaM chez les enfants atteints de PC de leurs pairs en développement typique (DT) pendant la marche. Cet objectif a été atteint en deux étapes ; Premièrement, nous avons décrit la CoM/CaM chez les personnes atteintes de PC via la réalisation d'une revue de littérature ; Ensuite, nous avons appliqué nos résultats de la première étape à une étude transversale pour comparer CoM/CaM pendant la marche entre des enfants atteints de CP et de DT. Une revue de littérature suivant la méthodologie en 6 étapes du Joanna Briggs Institute a été effectué. Les bases de données ont été consultées à l'aide de mots-clés pertinents. Toutes les études publiées sur CoM/CaM chez les personnes atteintes de PC pendant la marche ont été recueillies. Après un examen de la pertinence des titres et des résumés, un deuxième examen des textes intégraux des sources par deux examinateurs a été appliqué. Enfin, les données ont été extraites des articles inclus (n=21). Ensuite, à l'étape suivante, les principales méthodes utilisées pour quantifier la MCa identifiées à l'étape précédente ont été codées dans Matlab (The Mathworks Inc., Natick, États-Unis) et appliquées à nos données de 12 enfants atteints de CP et 23 enfants TD. Nous avons comparé le CaM moyen de deux groupes de muscles de la cuisse et de la jambe (Rectus Femoris (RF)/Semitendinosus (ST) et Tibialis Anterior (TA)/Lateral gastrocnemius (LG), respectivement) via des tests t non appariés (ou son équivalent non paramétrique). La revue de littérature a suggéré une CaM plus élevée chez les personnes atteintes de PC par rapport à leurs pairs en bonne santé dans toutes les études. Bien qu'il y ait eu une terminologie et des approches méthodologiques incohérentes, nous avons pu discriminer les terminologies (c'est-à-dire CoM et CaM) en fonction des méthodologies de calcul (c'est-à-dire moment et EMG) utilisées par les études. En outre, cette étude nous a permis de résumer les modèles de CaM chez les individus atteints de PC et d'identifier la relation entre certains des paramètres de marche avec CaM. Enfin, les résultats de cette étude ont révélé des informations précieuses concernant les lacunes de la recherche dans ce domaine. La deuxième étude a identifié une augmentation de la CaM pendant la marche (la foulée entière, la phase d’appuie et la phase oscillante) chez les enfants atteints de PC par rapport à leurs pairs TD. Cette augmentation n'a été observée que dans les muscles de la jambe (pendant la phase d’appuie et la phase oscillante) et dans les muscles de la cuisse (pendant la phase oscillante) lorsque nous avons normalisé les signaux d'électromyographie. Les groupes CP et DT n'avaient pas de CaM différent en utilisant l'EMG normalisé pour l'ensemble de la foulée. Cette différence met en évidence l'effet de la normalisation EMG sur les valeurs de CaM. De plus, les enfants avec le niveau II du système de classification de la fonction motrice globale (SCFMG) avaient un CaM plus élevé dans les muscles de la cuisse pendant le swing que ceux avec le niveau I. Dans l'ensemble, ce projet de maîtrise révèle de nouvelles preuves soutenant une plus grande CaM chez les enfants atteints de PC par rapport à DT pendant la marche. Néanmoins, il est important d'étudier la CaM dans différentes phases de marche car elle affecte la comparaison entre les groupes. En outre, ce projet justifie l'importance de la méthodologie (par exemple, le traitement EMG et le calcul CaM) dans les études CaM. Plus précisément, il est fort probable que les résultats changent avec différentes approches de normalisation EMG. De plus, les enfants atteints de SCFMG I et II peuvent éprouver différents niveaux de CaM pendant la phase oscillante. Davantage de comparaisons dans des recherches futures, telles qu'entre les SCFMG I, II et III dans la PC hémiplégique et diplégique pendant les sous-phases de la marche (le contact initial, le « mid-stance »), peuvent fournir de meilleures informations sur les modèles de CaM dans cette population.Cerebral palsy (CP) is a nonprogressive disorder caused by a brain injury. CP occurs early in life, before, during, or after birth, and has heterogeneous involvement and functional impairment. In individuals with CP, changes in neural drive and muscles lead to lifelong changes in motor function, leading to movement deficits. One of the reasons for atypical gait patterns in children with CP is altered muscle activation patterns. An abnormal level of simultaneous activation of agonist and antagonist muscles crossing the same joint prevents optimal gait performance in children with CP. This phenomenon is known as muscle co-contraction (MCo) or muscle co-activation (MCa) across studies. Identification of the most deteriorated muscular patterns, namely, MCo/MCa, in children with CP is vital for effective gait rehabilitation. The objective of this master’s project, therefore, was to distinguish MCo/MCa in children with CP from their typically developing (TD) peers during gait. This objective was achieved through two studies; first, we described MCo/MCa in individuals with CP via the conduction of a scoping review; then, we applied our findings to inform a cross-sectional study to compare MCo/MCa during gait between children with CP and TD. A scoping review following the 6-stage Joanna Briggs Institute methodology was conducted. Databases were searched using relevant keywords. All published studies on MCo/MCa in individuals with CP during gait were collected. After title and abstract relevance screening, a second screening for the full texts of the sources by two reviewers was applied. Finally, data were extracted from the included articles (n=21). Then, leading methods used to quantify MCa identified from the previous study were coded in Matlab (The Mathworks Inc., Natick, USA) and applied to our data from 12 children with CP and 23 TD children. We compared the average MCa of two thigh and shank muscle groups Rectus Femoris (RF)/Semitendinosus (ST) and Tibialis Anterior (TA)/Lateral gastrocnemius (LG), respectively, via unpaired t-tests (or its non-parametric equivalent). According to our scoping review, higher MCa in individuals with CP compared to healthy peers across studies was found. Although there were inconsistent terminology and methodological approaches, we could discriminate terminologies (i.e., MCo and MCa) according to the methodologies in the calculation (i.e., moment and EMG) used by studies. Also, this study enabled us to summarize MCa patterns within individuals with CP and identify the effect of the some of the gait parameters on MCa. Finally, the findings of this study revealed valuable information regarding the research gaps in this area. The second study identified increased MCa around the knee and ankle joints for the following muscles (i.e., RF/ST and TA/LG, respectively) during walking (i.e., entire stride, stance, and swing) in children with CP compared to their TD peers. This increase was seen only in shank muscles (i.e., during stance and swing) and in thigh muscles (i.e., during the swing) when we normalized electromyography (EMG) signals. CP and TD groups did not have different MCa using normalized EMG for the entire stride. This difference highlights the effect of EMG normalization on MCa values. Also, children with Gross Motor Function Classification System (GMFCS) level II had higher MCa around the knee during swing than those with level I. Overall, this master’s project reveals new evidence supporting greater MCa in children with CP compared to TD peers during walking. Nevertheless, it is recommended to investigate MCa within different gait phases as it affects the comparison across groups. Also, this project justifies the importance of methodology (e.g., EMG processing and MCa calculation) in MCa studies. More specifically, it is likely that the results alter with different EMG normalization approaches. Moreover, children with GMFCS I and II can experience various levels of MCa during the swing phase. More comparisons in future research, such as between GMFCS I, II, and III in hemiplegic and diplegic CP during gait sub-phases (i.e., initial stance, mid-stance), can provide better information regarding MCa patterns in this population

Recent Advances in Motion Analysis

The advances in the technology and methodology for human movement capture and analysis over the last decade have been remarkable. Besides acknowledged approaches for kinematic, dynamic, and electromyographic (EMG) analysis carried out in the laboratory, more recently developed devices, such as wearables, inertial measurement units, ambient sensors, and cameras or depth sensors, have been adopted on a wide scale. Furthermore, computational intelligence (CI) methods, such as artificial neural networks, have recently emerged as promising tools for the development and application of intelligent systems in motion analysis. Thus, the synergy of classic instrumentation and novel smart devices and techniques has created unique capabilities in the continuous monitoring of motor behaviors in different fields, such as clinics, sports, and ergonomics. However, real-time sensing, signal processing, human activity recognition, and characterization and interpretation of motion metrics and behaviors from sensor data still representing a challenging problem not only in laboratories but also at home and in the community. This book addresses open research issues related to the improvement of classic approaches and the development of novel technologies and techniques in the domain of motion analysis in all the various fields of application

Enhancing Biomechanical Function through Development and Testing of Assistive Devices for Shoulder Impairment and Total Limb Amputation

Assistive devices serve as a potential for restoring sensorimotor function to impaired individuals. My research focuses on two assistive devices: a passive shoulder exoskeleton and a muscle-driven endoprosthesis (MDE). Previous passive shoulder exoskeletons have focused on testing during static loading conditions in the shoulder. However, activities of daily living are based on dynamic tasks. My research for passive shoulder exoskeletons analyzes the effect that a continuous passive assistance has on shoulder biomechanics. In my research I showed that passive assistance decreases the muscular activation in muscles responsible for positive shoulder exoskeleton. An MDE has the potential to have accurate and precise control of movement as well as restore a sense of proprioception to the user. Such a transformative and invasive device has never previously been tested. Therefore, my research focused on analyzing fundamental principles of the MDE in an in-vivo rabbit model. The two concepts I tested in my research were the feasibility of implanting an orthopedic device underneath the skin at the distal end of a limb following amputation and the locomotor restorative capabilities of an artificial tendon used for muscle-device connection. In my work I proved the feasibility of implanting fully-footed rigid endoprostheses underneath the skin and isolated the primary factors for a successful surgery and recovery. In addition, my research showed that although artificial tendons have the potential to restore locomotor function, proper in-situ tendon lengths must be achieved for optimal movement. This research informed the design and testing of a fully jointed muscle-driven endoprosthesis prototype

Rehabilitation Engineering

Population ageing has major consequences and implications in all areas of our daily life as well as other important aspects, such as economic growth, savings, investment and consumption, labour markets, pensions, property and care from one generation to another. Additionally, health and related care, family composition and life-style, housing and migration are also affected. Given the rapid increase in the aging of the population and the further increase that is expected in the coming years, an important problem that has to be faced is the corresponding increase in chronic illness, disabilities, and loss of functional independence endemic to the elderly (WHO 2008). For this reason, novel methods of rehabilitation and care management are urgently needed. This book covers many rehabilitation support systems and robots developed for upper limbs, lower limbs as well as visually impaired condition. Other than upper limbs, the lower limb research works are also discussed like motorized foot rest for electric powered wheelchair and standing assistance device