Technologically-advanced assessment of upper-limb spasticity: a pilot study.

BACKGROUND: Spasticity is a muscle disorder associated with upper motor neuron syndrome occurring in neurological disorders, such as stroke, multiple sclerosis, spinal cord injury and others. It influences the patient's rehabilitation, interfering with function, limiting independence, causing pain and producing secondary impairments, such as contractures or other complications. Due to the heterogeneity of clinical signs of spasticity, there is no agreement on the most appropriate assessment and measurement modality for the evaluation of treatment outcomes. AIM: The aim of this article is to propose the use of new robotic devices for upper-limb spasticity assessment and describe the most relevant measures of spasticity which could be automatically assessed by using a technologically advanced device. DESIGN: Observational pilot study. SETTING: The treatment was provided in a Rehabilitation Centre where the device was located and the subjects were treated in an outpatients setting. POPULATION: Five post-stroke patients, age range 19-79 years (mean age 61, standard deviation [SD]±25) in their chronic phase. METHODS: A new robotic device able to automatically assess upper-limb spasticity during passive and active mobilization has been developed. The elbow spasticity of five post stroke patients has been assessed by using the new device and by means of the Modified Ashworth Scale (MAS). After the first assessment, subjects were treated with botulin toxin injections, and then underwent 10 sessions of robotic treatments. After the treatment, subjects spasticity was assessed by using the robotic device and the MAS Score. RESULTS: In four out of five patients, the botulin toxin injection and robotic treatment resulted in the improvement of the MAS Score; in three patients the robotic measures were able to detect the MAS changes. In one subject botulin toxin was not effective and the robotic device was able to detect the lack of effectiveness. CONCLUSIONS: By using the robotic device some spasticity parameters can be continuously recorded during the rehabilitation treatment in order to objectively measure the effectiveness of the interventions provided. CLINICAL REHABILITATION IMPACT: The standardized evaluation parameters recorded using robotic devices may provide several advantages: 1) the measures for spasticity assessment can be monitored during every rehabilitation session (even during each movement); 2) these measurements are able to highlight even small changes; 3) the recovery plateau can be detected early thus avoiding further rehabilitation sessions; and 4) these measurements can reduce the assessment bias in multicenter studies.

A lightweight robotic ankle prosthesis with non-backdrivable cam-based transmission.

Below-knee level amputation significantly impacts the ability of an individual to ambulate. Transtibial amputees are typically prescribed energetically passive ankle-foot prostheses that behave as a spring or controlled damper, and therefore cannot fully replace the function of the missing limb. More recently, fully-powered devices have been proposed to more closely match the power generation ability of intact limbs. However, these fully-powered devices are significantly heavier than passive devices, thus increasing the stress on the socket-residual limb interface. An alternative solution consists of using a motorized mechanism to actively reposition the foot during non-weight-bearing phases. By using this approach, the Össur© PROPRIO FOOT® showed promising outcomes such as improved gait energetics at self-selected speed, symmetry, and comfort. However, this device cannot be used by many transtibial amputees due to large build height (180 mm). Moreover, its weight has been shown critical for socket suspension. To address these limitations, we propose a novel non-backdrivable cam-based transmission. Based on this novel transmission, we developed a compact, lightweight ankle foot prosthesis. Bench-top testing and preliminary experiments with an able-bodied subject show that the proposed design can actively reposition the foot in swing as necessary to increase foot clearance, while adapting the ankle position to the ground inclination in stance.

Phase-II Clinical Validation of a Powered Exoskeleton for the Treatment of Elbow Spasticity.

Introduction: Spasticity is a typical motor disorder in patients affected by stroke. Typically post-stroke rehabilitation consists of repetition of mobilization exercises on impaired limbs, aimed to reduce muscle hypertonia and mitigate spastic reflexes. It is currently strongly debated if the treatment's effectiveness improves with the timeliness of its adoption; in particular, starting intensive rehabilitation as close as possible to the stroke event may counteract the growth and postpone the onset of spasticity. In this paper we present a phase-II clinical validation of a robotic exoskeleton in treating subacute post-stroke patients. Methods: Seventeen post-stroke patients participated in 10 daily rehabilitation sessions using the NEUROExos Elbow Module exoskeleton, each one lasting 45 min: the exercises consisted of isokinetic passive mobilization of the elbow, with torque threshold to detect excessive user's resistance to the movement. We investigated the safety by reporting possible adverse events, such as mechanical, electrical or software failures of the device or injuries or pain experienced by the patient. As regards the efficacy, the Modified Ashworth Scale, was identified as primary outcome measure and the NEEM metrics describing elbow joint resistance to passive extension (i.e., maximum extension torque and zero-torque angle) as secondary outcomes. Results: During the entire duration of the treatments no failures or adverse events for the patients were reported. No statistically significant differences were found in the Modified Ashworth Scale scores, between pre-treatment and post-treatment and between post-treatment and follow-up sessions, indicating the absence of spasticity increase throughout (14 days) and after (3-4 months follow-up) the treatment. Exoskeleton metrics confirmed the absence of significant difference in between pre- and post-treatment data, whereas intra-session data highlighted significant differences in the secondary outcomes, toward a decrease of the subject's joint resistance. Conclusions: The results show that our robotic exoskeleton can be safely used for prolonged sessions in post-stroke and suggest that intensive early rehabilitation treatment may prevent the occurrence of spasticity at a later stage. Moreover, the NEEM metrics were found to be reliable compared to the Modified Ashworth Scale and sensitive to revealing intra-session changes of elbow resistance to passive extension, in agreement with clinical evidences.

Physical human-robot interaction of an active pelvis orthosis: toward ergonomic assessment of wearable robots.

BACKGROUND: In human-centered robotics, exoskeletons are becoming relevant for addressing needs in the healthcare and industrial domains. Owing to their close interaction with the user, the safety and ergonomics of these systems are critical design features that require systematic evaluation methodologies. Proper transfer of mechanical power requires optimal tuning of the kinematic coupling between the robotic and anatomical joint rotation axes. We present the methods and results of an experimental evaluation of the physical interaction with an active pelvis orthosis (APO). This device was designed to effectively assist in hip flexion-extension during locomotion with a minimum impact on the physiological human kinematics, owing to a set of passive degrees of freedom for self-alignment of the human and robotic hip flexion-extension axes. METHODS: Five healthy volunteers walked on a treadmill at different speeds without and with the APO under different levels of assistance. The user-APO physical interaction was evaluated in terms of: (i) the deviation of human lower-limb joint kinematics when wearing the APO with respect to the physiological behavior (i.e., without the APO); (ii) relative displacements between the APO orthotic shells and the corresponding body segments; and (iii) the discrepancy between the kinematics of the APO and the wearer's hip joints. RESULTS: The results show: (i) negligible interference of the APO in human kinematics under all the experimented conditions; (ii) small (i.e., < 1 cm) relative displacements between the APO cuffs and the corresponding body segments (called stability); and (iii) significant increment in the human-robot kinematics discrepancy at the hip flexion-extension joint associated with speed and assistance level increase. CONCLUSIONS: APO mechanics and actuation have negligible interference in human locomotion. Human kinematics was not affected by the APO under all tested conditions. In addition, under all tested conditions, there was no relevant relative displacement between the orthotic cuffs and the corresponding anatomical segments. Hence, the physical human-robot coupling is reliable. These facts prove that the adopted mechanical design of passive degrees of freedom allows an effective human-robot kinematic coupling. We believe that this analysis may be useful for the definition of evaluation metrics for the ergonomics assessment of wearable robots.

Usability test of a hand exoskeleton for activities of daily living: an example of user-centered design.

PURPOSE: (1) To assess a robotic device (Handexos) during the design process with regard to usability, end user satisfaction and safety, (2) to determine whether Handexos can improve the activities of daily living (ADLs) of spinal cord injury (SCI) patients and stroke patients with upper-limb dysfunction. METHODS: During a 2-year development stage of the device, a total of 37 participants (aged 22-68), 28 clinicians (experts) and nine patients with SCI or stroke (end users) were included in a user-centered design process featuring usability tests. They performed five grasps wearing the device. The assessments were obtained at the end of the session by filling out a questionnaire and making suggestions. RESULTS: The experts' opinion was that the modified device was an improvement over the preliminary version, although this was not reflected in the scores. Whereas end user scores for comfort, grasp, performance and safety were above the sufficiency threshold, the scores for year 2 were lower than those for year 1. CONCLUSIONS: The findings demonstrate that although Handexos meets the initial functional requirements and underlines the potential for assisting SCI and post-stroke subjects in ADLs, several aspects such as mechanical complexity and low adaptability to different hand sizes need to be further addressed. Implications for Rehabilitation Wearable robotics devices could improve the activities of daily living in patients with spinal cord injury or stroke. They could be a tool for rehabilitation of the upper limb. Further usability tests to improve this type of tools are recommended.

Vision-Based Pose Estimation for Robot-Mediated Hand Telerehabilitation.

Vision-based Pose Estimation (VPE) represents a non-invasive solution to allow a smooth and natural interaction between a human user and a robotic system, without requiring complex calibration procedures. Moreover, VPE interfaces are gaining momentum as they are highly intuitive, such that they can be used from untrained personnel (e.g., a generic caregiver) even in delicate tasks as rehabilitation exercises. In this paper, we present a novel master-slave setup for hand telerehabilitation with an intuitive and simple interface for remote control of a wearable hand exoskeleton, named HX. While performing rehabilitative exercises, the master unit evaluates the 3D position of a human operator's hand joints in real-time using only a RGB-D camera, and commands remotely the slave exoskeleton. Within the slave unit, the exoskeleton replicates hand movements and an external grip sensor records interaction forces, that are fed back to the operator-therapist, allowing a direct real-time assessment of the rehabilitative task. Experimental data collected with an operator and six volunteers are provided to show the feasibility of the proposed system and its performances. The results demonstrate that, leveraging on our system, the operator was able to directly control volunteers' hands movements.

Gastrocnemius myoelectric control of a robotic hip exoskeleton.

In this paper we present a novel EMG-based assistive control strategy for lower-limb exoskeletons. An active pelvis orthosis (APO) generates torque profiles for the hip flexion motion assistance, according to the Gastrocnemius Medialis EMG signal. The strategy has been tested on one healthy subject: experimental results show that the user is able to reduce his muscular activation when the assistance is switched on with respect to the free walking condition.

Enhancing brain-machine interface (BMI) control of a hand exoskeleton using electrooculography (EOG).

BACKGROUND: Brain-machine interfaces (BMIs) allow direct translation of electric, magnetic or metabolic brain signals into control commands of external devices such as robots, prostheses or exoskeletons. However, non-stationarity of brain signals and susceptibility to biological or environmental artifacts impede reliable control and safety of BMIs, particularly in daily life environments. Here we introduce and tested a novel hybrid brain-neural computer interaction (BNCI) system fusing electroencephalography (EEG) and electrooculography (EOG) to enhance reliability and safety of continuous hand exoskeleton-driven grasping motions. FINDINGS: 12 healthy volunteers (8 male, mean age 28.1 ± 3.63y) used EEG (condition #1) and hybrid EEG/EOG (condition #2) signals to control a hand exoskeleton. Motor imagery-related brain activity was translated into exoskeleton-driven hand closing motions. Unintended motions could be interrupted by eye movement-related EOG signals. In order to evaluate BNCI control and safety, participants were instructed to follow a visual cue indicating either to move or not to move the hand exoskeleton in a random order. Movements exceeding 25% of a full grasping motion when the device was not supposed to be moved were defined as safety violation. While participants reached comparable control under both conditions, safety was frequently violated under condition #1 (EEG), but not under condition #2 (EEG/EOG). CONCLUSION: EEG/EOG biosignal fusion can substantially enhance safety of assistive BNCI systems improving their applicability in daily life environments.

Analysis of relative displacement between the HX wearable robotic exoskeleton and the user's hand.

BACKGROUND: Advances in technology are allowing for the production of several viable wearable robotic devices to assist with activities of daily living and with rehabilitation. One of the most pressing limitations to user satisfaction is the lack of consistency in motion between the user and the robotic device. The displacement between the robot and the body segment may not correspond because of differences in skin and tissue compliance, mechanical backlash, and/or incorrect fit. FINDINGS: This report presents the results of an analysis of relative displacement between the user's hand and a wearable exoskeleton, the HX. HX has been designed to maximize comfort, wearability and user safety, exploiting chains with multiple degrees-of-freedom with a modular architecture. These appealing features may introduce several uncertainties in the kinematic performances, especially when considering the anthropometry, morphology and degree of mobility of the human hand. The small relative displacements between the hand and the exoskeleton were measured with a video-based motion capture system, while the user executed several different grips in different exoskeleton modes. CONCLUSIONS: The analysis furnished quantitative results about the device performance, differentiated among device modules and test conditions. In general, the global relative displacement for the distal part of the device was in the range 0.5-1.5 mm, while within 3 mm (worse but still acceptable) for displacements nearest to the hand dorsum. Conclusions over the HX design principles have been drawn, as well as guidelines for future developments.

Kinematics and design of a portable and wearable exoskeleton for hand rehabilitation.

We present the kinematic design and actuation mechanics of a wearable exoskeleton for hand rehabilitation of post-stroke. Our design method is focused on achieving maximum safety, comfort and reliability in the interaction, and allowing different users to wear the device with no manual regulations. In particular, we propose a kinematic and actuation solution for the index finger flexion/extension, which leaves full movement freedom on the abduction-adduction plane. This paper presents a detailed kineto-static analysis of the system and a first prototype of the device.

NEUROExos: A powered elbow orthosis for post-stroke early neurorehabilitation.

This paper presents the development of a portable version of the robotic elbow exoskeleton NEUROExos, designed for the treatment of stroke survivors in acute/sub-acute phases. The design was improved by a novel Series Elastic Actuation (SEA) system. The system implements two control modalities: a near-zero output impedance torque control and a passive-compliance position control.

On the design of ergonomic wearable robotic devices for motion assistance and rehabilitation.

The appropriate ergonomic design of a wearable robotic device is critical for the effectiveness of the device itself. In this paper we identified two key requirements for a structural ergonomics: the correct kinematic compatibility with the human limb and a comfortable and adaptable physical human-robot interface. We then show how the aforementioned requirements have been faced and implemented in the mechanical design of two wearable devices for elbow and hand rehabilitation, both developed at The BioRobotics Institute of Scuola Superiore Sant' Anna.