Wearable rehabilitation exoskeletons of the lower limb: analysis of versatility and adaptability

From bedside to recovery: exercise therapy for prevention of post-intensive care syndrome

BACKGROUND

As advancements in critical care medicine continue to improve Intensive Care Unit (ICU) survival rates, clinical and research attention is urgently shifting toward improving the quality of survival. Post-Intensive Care Syndrome (PICS) is a complex constellation of physical, cognitive, and mental dysfunctions that severely impact patients' lives after hospital discharge. This review provides a comprehensive and multi-dimensional summary of the current evidence and practice of exercise therapy (ET) during and after an ICU admission to prevent and manage the various domains of PICS. The review aims to elucidate the evidence of the mechanisms and effects of ET in ICU rehabilitation and highlight that suboptimal clinical and functional outcomes of ICU patients is a growing public health concern that needs to be urgently addressed.

MAIN BODY

This review commences with a brief overview of the current relationship between PICS and ET, describing the latest research on this topic. It subsequently summarises the use of ET in ICU, hospital wards, and post-hospital discharge, illuminating the problematic transition between these settings. The following chapters focus on the effects of ET on physical, cognitive, and mental function, detailing the multi-faceted biological and pathophysiological mechanisms of dysfunctions and the benefits of ET in all three domains. This is followed by a chapter focusing on co-interventions and how to maximise and enhance the effect of ET, outlining practical strategies for how to optimise the effectiveness of ET. The review next describes several emerging technologies that have been introduced/suggested to augment and support the provision of ET during and after ICU admission. Lastly, the review discusses future research directions.

CONCLUSION

PICS is a growing global healthcare concern. This review aims to guide clinicians, researchers, policymakers, and healthcare providers in utilising ET as a therapeutic and preventive measure for patients during and after an ICU admission to address this problem. An improved understanding of the effectiveness of ET and the clinical and research gaps that needs to be urgently addressed will greatly assist clinicians in their efforts to rehabilitate ICU survivors, improving patients' quality of survival and helping them return to their normal lives after hospital discharge.

Design and motion control of exoskeleton robot for paralyzed lower limb rehabilitation

Introduction

Patients suffering from limb movement disorders require more complete rehabilitation treatment, and there is a huge demand for rehabilitation exoskeleton robots. Flexible and reliable motion control of exoskeleton robots is very important for patient rehabilitation.

Methods

This paper proposes a novel exoskeleton robotic system for lower limb rehabilitation. The designed lower limb rehabilitation exoskeleton robot mechanism is mainly composed of the hip joint mechanism, the knee joint mechanism and the ankle joint mechanism. The forces and motion of the exoskeleton robot were analyzed in detail to determine its design parameters. The robot control system was developed to implement closed-loop position control and trajectory planning control of each joint mechanism.

Results

Multiple experiments and tests were carried out to verify robot's performance and practicality. In the robot angular response experiments, the joint mechanism could quickly adjust to different desired angles, including 15°, 30°, 45°, and 60°. In the trajectory tracking experiments, the exoskeleton robot could complete tracking movements of typical actions such as walking, standing up, sitting down, go upstairs and go downstairs, with a maximum tracking error of ±5°. Robotic wearing tests on normal people were performed to verify the assistive effects of the lower limb rehabilitation exoskeleton at different stages.

Discussion

The experimental results indicated that the exoskeleton robot has excellent reliability and practicality. The application of this exoskeleton robotic system will help paralyzed patients perform some daily movements and sports.

Patent Review of Lower Limb Rehabilitation Robotic Systems by Sensors and Actuation Systems Used

Robotic systems for lower limb rehabilitation are essential for improving patients' physical conditions in lower limb rehabilitation and assisting patients with various locomotor dysfunctions. These robotic systems mainly integrate sensors, actuation, and control systems and combine features from bionics, robotics, control, medicine, and other interdisciplinary fields. Several lower limb robotic systems have been proposed in the patent literature; some are commercially available. This review is an in-depth study of the patents related to robotic rehabilitation systems for lower limbs from the point of view of the sensors and actuation systems used. The patents awarded and published between 2013 and 2023 were investigated, and the temporal distribution of these patents is presented. Our results were obtained by examining the analyzed information from the three public patent databases. The patents were selected so that there were no duplicates after several filters were used in this review. For each patent database, the patents were analyzed according to the category of sensors and the number of sensors used. Additionally, for the main categories of sensors, an analysis was conducted depending on the type of sensors used. Afterwards, the actuation solutions for robotic rehabilitation systems for upper limbs described in the patents were analyzed, highlighting the main trends in their use. The results are presented with a schematic approach so that any user can easily find patents that use a specific type of sensor or a particular type of actuation system, and the sensors or actuation systems recommended to be used in some instances are highlighted.

Satisfaction analysis of overground gait exoskeletons in people with neurological pathology. a systematic review

BACKGROUND

People diagnosed with neurological pathology may experience gait disorders that affect their quality of life. In recent years, research has been carried out on a variety of exoskeletons in this population. However, the satisfaction perceived by the users of these devices is not known. Therefore, the objective of the present study is to evaluate the satisfaction perceived by users with neurological pathology (patients and professionals) after the use of overground exoskeletons.

METHODS

A systematic search of five electronic databases was conducted. In order to be included in this review for further analysis, the studies had to meet the following criteria: [1] the study population was people diagnosed with neurological pathology; [2] the exoskeletons had to be overground and attachable to the lower limbs; and [3]: the studies were to include measures assessing either patient or therapist satisfaction with the exoskeletons.

RESULTS

Twenty-three articles were selected, of which nineteen were considered clinical trials. Participants diagnosed with stroke (n = 165), spinal cord injury (SCI) (n = 102) and multiple sclerosis (MS) (n = 68). Fourteen different overground exoskeleton models were analysed. Fourteen different methods of assessing patient satisfaction with the devices were found, and three ways to evaluate it in therapists.

CONCLUSION

Users' satisfaction with gait overground exoskeletons in stroke, SCI and MS seems to show positive results in safety, efficacy and comfort of the devices. However, the worst rated aspects and therefore those that should be optimized from the users' point of view are ease of adjustment, size and weight, and ease of use.

Higher Responsiveness of Pattern Generation Circuitry to Sensory Stimulation in Healthy Humans Is Associated with a Larger Hoffmann Reflex

Simple Summary

Individual differences in the sensorimotor circuitry play an important role for understanding the nature of behavioral variability and developing personalized therapies. While the spinal network likely requires relatively rigid organization, it becomes increasingly evident that adaptability and inter-individual variability in the functioning of the neuronal circuitry is present not only in the brain but also in the spinal cord. In this study we investigated the relationship between the excitability of pattern generation circuitry and segmental reflexes in healthy humans. We found that the high individual responsiveness of pattern generation circuitries to tonic sensory input in both the upper and lower limbs was related to larger H-reflexes. The results provide further evidence for the importance of physiologically relevant assessments of spinal cord neuromodulation and the individual physiological state of reflex pathways.

Abstract

The state and excitability of pattern generators are attracting the increasing interest of neurophysiologists and clinicians for understanding the mechanisms of the rhythmogenesis and neuromodulation of the human spinal cord. It has been previously shown that tonic sensory stimulation can elicit non-voluntary stepping-like movements in non-injured subjects when their limbs were placed in a gravity-neutral unloading apparatus. However, large individual differences in responsiveness to such stimuli were observed, so that the effects of sensory neuromodulation manifest only in some of the subjects. Given that spinal reflexes are an integral part of the neuronal circuitry, here we investigated the extent to which spinal pattern generation excitability in response to the vibrostimulation of muscle proprioceptors can be related to the H-reflex magnitude, in both the lower and upper limbs. For the H-reflex measurements, three conditions were used: stationary limbs, voluntary limb movement and passive limb movement. The results showed that the H-reflex was considerably higher in the group of participants who demonstrated non-voluntary rhythmic responses than it was in the participants who did not demonstrate them. Our findings are consistent with the idea that spinal reflex measurements play important roles in assessing the rhythmogenesis of the spinal cord.

Robust LQR-Based Neural-Fuzzy Tracking Control for a Lower Limb Exoskeleton System with Parametric Uncertainties and External Disturbances

The design of an accurate control scheme for a lower limb exoskeleton system has few challenges due to the uncertain dynamics and the unintended subject's reflexes during gait rehabilitation. In this work, a robust linear quadratic regulator- (LQR-) based neural-fuzzy (NF) control scheme is proposed to address the effect of payload uncertainties and external disturbances during passive-assist gait training. Initially, the Euler-Lagrange principle-based nonlinear dynamic relations are established for the coupled system. The input-output feedback linearization approach is used to transform the nonlinear relations into a linearized state-space form. The architecture of the adaptive neuro-fuzzy inference system (ANFIS) and used membership function are briefly explained. While varying mass parameters up to 20%, three robust neural-fuzzy datasets are formulated offline with the joint error vector and LQR control input. Thereafter, to deal with external interferences, an error dynamics with a disturbance estimator is presented using an online adaptation of the firing strength matrix. The Lyapunov theory is carried out to ensure the asymptotic stability of the coupled human-exoskeleton system in view of the proposed controller. The gait tracking results for the proposed control scheme (RLQR-NF) are presented and compared with the exponential reaching law-based sliding mode (ERL-SM) controller. Furthermore, to investigate the robustness of the proposed control over LQR control, a comparative performance analysis is presented for two cases of parametric uncertainties and external disturbances. The first case considers the 20% raise in mass values with a trigonometric form of disturbances, and the second case includes the effect of the 30% increment in mass values with a random form of disturbances. The simulation runs have shown the promising gait tracking aspects of the designed controller for passive-assist gait training.