On the assessment of coordination between upper extremities: towards a common language between rehabilitation engineers, clinicians and neuroscientists

The role of different acoustic environmental stimuli on manual dexterity

Music has been reported to facilitate motor performance. However, there is no data on the effects of different acoustic environmental stimuli on manual dexterity. The present observational study aimed at investigating the effects of background music and noise on a manual dexterity task in young, middle-aged and elderly subjects. Sixty healthy, right-handed subjects aged between 18 and 80 years were enrolled. Twenty young (mean age: 22±2 years), 20 middle-aged (mean age: 55±8 years) and 20 elderly (mean age: 72±5 years) subjects performed the Nine Hole Peg Test (NHPT) in four different acoustic environments: silence (noise < 20dBA), classical music at 60dBA, rock music at 70 dBA, and a noise stimulus at 80dBA. Performance was recorded using an optical motion capture system and retro-reflective markers (SMART DX, 400, BTS). Outcome measures included the total test time and peg-grasp, peg-transfer, peg-in-hole, hand-return, and removing phases times. Normalized jerk, mean and peak of velocity during transfer and return phases were also computed. No differences were found for NHPT phases and total times, normalized jerk, peak of velocity and mean velocity between four acoustic conditions (p>0.05). Between-group differences were found for NHPT total time, where young subjects revealed better performance than elderly (p˂0.001) and middle-aged (p˂0.001) groups. Music and noise stimuli in the considered range of intensity had no influence on the execution of a manual dexterity task in young, middle-aged and elderly subjects. These findings may have implications for working, sportive and rehabilitative activities.

Intra-limb joint coordination measures of upper limb and hand movements: A systematic review

BACKGROUND

People with central nervous system disorders typically have difficulties in coordination of the upper limb and hand movements, which significantly impairs their activities of daily living. Laboratory-based measures can provide quantitative and objective information about intra-limb coordination to aid the rehabilitation process of this population. However, there is currently no comprehensive review of laboratory-based measures.

RESEARCH QUESTIONS

The aim of this review was to identify and summarize laboratory-based intra-limb coordination measures for different upper limb and hand movements.

METHODS

Searches were performed in the CINAHL, Embase, IEEE Xplore, MEDLINE, PubMed and Web of Science databases to identify studies published between 2013 and 2022. Two authors independently performed paper selection, data extraction and quality assessment.

RESULTS

21 papers were identified, and six types of coordination measures were classified. These included principal component analysis, continuous relative phase analysis, correlation analysis, regression analysis, uncontrolled manifold analysis, and uncorrelated surrogate data analysis, in descending order of occurrence. Regarding psychometric properties, all measures demonstrated good discriminative validity. However, only the principal component analysis approach and the continuous relative phase analysis approach were found to have good convergent validity and responsiveness, respectively. In terms of their practicality, these measures were primarily utilized for quantifying coordination in individuals with neurological disorders, with a greater emphasis on the coordination of upper limb movements rather than hand movements.

SIGNIFICANCE

This review summarized and critiqued the characteristics of six types of joint coordination measures. Researchers and clinicians should therefore select appropriate measures based on individual needs. Future research should continue on analysing coordination in individuals with pathological conditions and exploring the application of these measures in quantifying hand movement coordination, to advance current knowledge and inform rehabilitation practices.

fMRI changes during multi-limb movements in Parkinson's disease

Background

While motor coordination problems are frequently reported among individuals with Parkinson’s disease (PD), the effects of the disease on the performance of multi-limb movements and the brain changes underlying impaired coordination are not well-documented.

Objective

Functional magnetic resonance imaging (fMRI) was used to examine differences in brain activity during a task that involved the coordination of non-homologous limbs (i.e., ipsilateral hand and foot) in individuals with and without PD.

Methods

Participants included 20 PD and 20 healthy control participants (HC). They were instructed to generate force in a coordinated manner by simultaneously contracting their ipsilateral hand and foot. PD were tested off their antiparkinsonian medication and on their more affected side, whereas the side in controls was randomized.

Results

Although both groups were able to coordinate the two limbs to produce the expected level of force, PD had a slower rate of force production and relaxation compared to HC. Additionally, their globus pallidus and primary motor cortex were underactive, whereas their pre-supplementary motor area (pre-SMA) and lateral cerebellum were overactive relative to HC. Importantly, in PD, the fMRI activity within the pre-SMA correlated with the rate of force decrease.

Conclusion

Multi-limb force control deficits in PD appear to be related to widespread underactivation within the basal ganglia-cortical loop. An overactivation of higher-level motor regions within the prefrontal cortex and lateral cerebellum may reflect increased cognitive control and performance monitoring that emerges during more complex motor tasks such as those that involve the coordination of multiple limbs.

A new device for assessment and training the human balance and coordination: Marmara Balance and Education System (MarBES)

BACKGROUND

Balance and coordination are important for performing activities of daily living. Balance and coordination assessment and training are used by physiotherapists in many different rehabilitation areas. Marmara Balance and Education System (MarBES) is a device developed to evaluate and improve balance and coordination.

AIMS

To examine the test-retest reliability of the MarBES device.

METHODS

Double-leg and single-leg (eyes open-closed) tests were applied to healthy young adult participants for balance testing on the MarBES device. Weight data is estimated from pressure sensors located in 4 different corners and a score is calculated with computer software for the individual's center of gravity (center of pressure X, Y) and the amount of deviation from the center for each axis. Weight transfer to the target surface was measured for assessment of the participants' coordination performance. Participants rested for 10 min and all measurements were repeated by the same evaluator. The obtained data were recorded and the reliability of the measurements was evaluated with Spearman's rho correlation analysis.

RESULTS

A total of 40 healthy young individuals (28 female) with a mean age of 21 years were included. The balance assessments with MarBES showed moderate to good reliability (ICC: 0.535-0.903). The coordination assessment results showed moderate to good reliability (ICC: 0.575-0.712).

CONCLUSIONS

Objective evaluation of balance and coordination parameters is very important in rehabilitation. Results of the study showed that the MarBES device developed by the researchers is a reliable method for the evaluation of balance and coordination in healthy young individuals.

A guide to inter-joint coordination characterization for discrete movements: a comparative study

Characterizing human movement is essential for understanding movement disorders, evaluating progress in rehabilitation, or even analyzing how a person adapts to the use of assistive devices. Thanks to the improvement of motion capture technology, recording human movement has become increasingly accessible and easier to conduct. Over the last few years, multiple methods have been proposed for characterizing inter-joint coordination. Despite this, there is no real consensus regarding how these different inter-joint coordination metrics should be applied when analyzing the coordination of discrete movement from kinematic data. In this work, we consider 12 coordination metrics identified from the literature and apply them to a simulated dataset based on reaching movements using two degrees of freedom. Each metric is evaluated according to eight criteria based on current understanding of human motor control physiology, i.e, each metric is graded on how well it fulfills each of these criteria. This comparative analysis highlights that no single inter-joint coordination metric can be considered as ideal. Depending on the movement characteristics that one seeks to understand, one or several metrics among those reviewed here may be pertinent in data analysis. We propose four main factors when choosing a metric (or a group of metrics): the importance of temporal vs. spatial coordination, the need for result explainability, the size of the dataset, and the computational resources. As a result, this study shows that extracting the relevant characteristics of inter-joint coordination is a scientific challenge and requires a methodical choice. As this preliminary study is conducted on a limited dataset, a more comprehensive analysis, introducing more variability, could be complementary to these results.

Biomechanical modeling for the estimation of muscle forces: toward a common language in biomechanics, medical engineering, and neurosciences

Different research fields, such as biomechanics, medical engineering or neurosciences take part in the development of biomechanical models allowing for the estimation of individual muscle forces involved in motor action. The heterogeneity of the terminology used to describe these models according to the research field is a source of confusion and can hamper collaboration between the different fields. This paper proposes a common language based on lexical disambiguation and a synthesis of the terms used in the literature in order to facilitate the understanding of the different elements of biomechanical modeling for force estimation, without questioning the relevance of the terms used in each field or the different model components or their interest. We suggest that the description should start with an indication of whether the muscle force estimation problem is solved following the physiological movement control (from the nervous drive to the muscle force production) or in the opposite direction. Next, the suitability of the model for force production estimation at a given time or for monitoring over time should be specified. Authors should pay particular attention to the method description used to find solutions, specifying whether this is done during or after data collection, with possible method adaptations during processing. Finally, the presence of additional data must be specified by indicating whether they are used to drive, assist, or calibrate the model. Describing and classifying models in this way will facilitate the use and application in all fields where the estimation of muscle forces is of real, direct, and concrete interest.

Differences in coordination between dominant and non-dominant hands in tele-operation. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2023;2023:1-4. [PMID: 38083449 DOI: 10.1109/embc40787.2023.10340192] [Citation(s) in RCA: 0] [Impact Index Per Article: 0]

The intuitive tele-operation of industrial robot arms is necessary for the teaching of autonomous movement. We developed a novel interface, namely the iFeel Desktop Haptic Device, for operating robots intuitively. However, when a user uses two interfaces with two hands, there are differences in coordination between the dominant and non-dominant hands. In this paper, we investigated the differences in coordination between dominant and non-dominant hands using two devices for the development of cooperative control. In an experiment, when the participants manipulated the two interfaces to operate a virtual tracking system, we measured the tracking error in each degree of freedom (i.e., X, Y, Z, pitch, yaw, and roll directions). The results show that there were significant differences between the dominant and non-dominant hands for movement in the X, Y, Z, and pitch directions. We conclude that the operations that involve more body parts have a greater difference between dominant and non-dominant hands.

Shaping Human Movement via Bimanually-Dependent Haptic Force Feedback

Haptic feedback can enhance training and performance of human operators; however, the design of haptic feedback for bimanual coordination in robot-assisted tasks (e.g., control of surgical robots) remains an open problem. In this study, we present four bimanually-dependent haptic force feedback conditions aimed at shaping bimanual movement according to geometric characteristics: the number of targets, direction, and symmetry. Haptic conditions include a virtual spring, damper, combination spring-damper, and dual springs placed between the hands. We evaluate the effects of these haptic conditions on trajectory shape, smoothness, and speed. We hypothesized that for subjects who perform worse with no haptic feedback (1) a spring will improve the shape of parallel trajectories, (2) a damper will improve the shape of point symmetric trajectories, (3) dual springs will improve the shape of trajectories with one target, and (4) a damper will improve smoothness for all trajectories. Hypotheses (1) and (2) were statistically supported at the p < 0.001 level, but hypotheses (3) and (4) were not supported. Moreover, bimanually-dependent haptic feedback tended to improve shape accuracy for movements that subjects performed worse on under no haptic condition. Thus, bimanual haptic feedback based on geometric trajectory characteristics shows promise to improve performance in robot-assisted motor tasks.

How virtual and mechanical coupling impact bimanual tracking

Bilateral training systems look to promote the paretic hand's use in individuals with hemiplegia. Although this is normally achieved using mechanical coupling (i.e., a physical connection between the hands), a virtual reality system relying on virtual coupling (i.e., through a shared virtual object) would be simpler to use and prevent slacking. However, it is not clear whether different coupling modes differently impact task performance and effort distribution between the hands. We explored how 18 healthy right-handed participants changed their motor behaviors in response to the uninstructed addition of mechanical coupling, and virtual coupling using a shared cursor mapped to the average hands' position. In a second experiment, we then studied the impact of connection stiffness on performance, perception, and effort imbalance. The results indicated that both coupling types can induce the hands to actively contribute to the task. However, the task asymmetry introduced by using a cursor mapped to either the left or right hand only modulated the hands' contribution when not mechanically coupled. The tracking performance was similar for all coupling types, independent of the connection stiffness, although the mechanical coupling was preferred and induced the hands to move with greater correlation. These findings suggest that virtual coupling can induce the hands to actively contribute to a task in healthy participants without hindering their performance. Further investigation on the coupling types' impact on the performance and hands' effort distribution in patients with hemiplegia could allow for the design of simpler training systems that promote the affected hand's use.NEW & NOTEWORTHY We showed that the uninstructed addition of a virtual and/or a mechanical coupling can induce both hands to actively contribute in a continuous redundant bimanual tracking task without impacting performance. In addition, we showed that the task asymmetry can only alter the effort distribution when the hands are not connected, independent of the connection stiffness. Our findings suggest that virtual coupling could be used in the development of simpler VR-based training devices.

Clinical Motor Coordination Tests in Adult Neurology: A Scoping Review

Purpose: This scoping review aimed to identify which clinical tests are used to assess upper limb, lower limb, and trunk motor coordination, and their metric and measurement properties for adult neurological populations. Method: MEDLINE (1946-) and EMBASE (1996-) databases were searched using keywords such as movement quality, motor performance, motor coordination, assessment, and psychometrics. Data regarding the body part assessed, neurological condition, psychometric properties, and scored metrics of spatial and/or temporal coordination were independently extracted by two reviewers. Alternate versions of some tests such as the Finger-to-Nose Test were included. Results: Fifty-one included articles yielded 2 tests measuring spatial coordination, 7 tests measuring temporal coordination, and 10 tests measuring both. Scoring metrics and measurement properties differed between tests, with a majority of tests having good-to-excellent measurement properties. Conclusions: The metrics of motor coordination scored by current tests vary. Since tests do not assess functional task performance, the onus falls on clinicians to infer the connection between coordination impairments and functional deficits. Clinical practice would benefit from the development of a battery of tests that assesses the metrics of coordination related to functional performance.

A Robotic System to Deliver Multiple Physically Bimanual Tasks via Varying Force Fields

Individuals with physical limb disabilities are often restricted to perform activities of daily life (ADLs). While efficacy of bilateral training has been demonstrated in improving physical coordination of human limbs, few robots have been developed in simulating people's ADLs integrated with task-specific force field control. This study sought to develop a bilateral robot for better task rendering of general ADLs (gADLs), where gADL-consistent workspace is achieved by setting linear motors in series, and haptic rendering of multiple bimanual tasks (coupled, uncoupled and semi-coupled) is enabled by regulating force fields between robotic handles. Experiments were conducted with human users, and our results present a viable method of a single robotic system in simulating multiple physically bimanual tasks. In future, the proposed robotic system is expected to be serving as a coordination training device, and its clinical efficacy will be also investigated.

Bilateral motor coordination during upper limb symmetric pushing movements at two levels of force resistance in healthy and post-stroke individuals

BACKGROUND

Impairments of the upper limb (UL) are common after a stroke and may affect bilateral coordination. A better understanding of UL bilateral coordination is required for designing innovative rehabilitation strategies.

OBJECTIVE

To assess bilateral coordination after stroke using time-distance, velocity and force parameters during an UL bilateral task performed by simultaneously pushing handles on a bilateral exerciser at two levels of force.

METHODS

Two groups were included to assess bilateral coordination on a newly designed bimanual exerciser- One group of individuals at least 3 months post-stroke (n = 19) with moderate impairment and one group of healthy individuals (n = 20). Participants performed linear movements by pushing simultaneously with both hands on instrumented handles. The task consisted of two one-minute trials performed in sitting at two levels of participants' maximum force (MF): 30% and 15%, with visual feedback. Time-distance parameters, spatial, velocity and force profiles were compared between groups, between levels of resistance and the first part (0-50%) and entire duration of the pushing cycles (0-100%).

RESULTS

The mean pushing time was longer at 30% MF compared to 15% MF in the stroke group. Spatial profiles, represented by hand positions on the rail, revealed that the paretic hand lagged slightly behind throughout the cycle. For velocity, both groups displayed good coordination. It was less coupled at 30% than 15% MF and a trend was observed toward more lag occurrence in the stroke group. Except for lower forces on the paretic side in the stroke group, the shape of the force profiles was similar between groups, sides and levels of resistance. For all parameters, the coordination was good up to 75% of the pushing cycle and decreased toward the end of the cycle.

CONCLUSIONS

Individuals after stroke presented with overall spatial and temporal coupling of the UL during bilateral pushing movements. The relay of information at different levels of the nervous system might explain the coordinated pushing movements and might be interesting for training UL coordination.

Electromechanical and Robotic Devices for Gait and Balance Rehabilitation of Children with Neurological Disability: A Systematic Review

In the last two decades, a growing interest has been focused on gait and balance robot-assisted rehabilitation in children with neurological disabilities. Robotic devices allow the implementation of intensive, task-specific training fostering functional recovery and neuroplasticity phenomena. However, limited attention has been paid to the protocols used in this research framework. This systematic review aims to provide an overview of the existing literature on robotic systems for the rehabilitation of gait and balance in children with neurological disabilities and their rehabilitation applications. The literature search was carried out independently and synchronously by three authors on the following databases: MEDLINE, Cochrane Library, PeDro, Institute of Electrical and Electronics Engineers, ScienceDirect, and Google Scholar. The data collected included three subsections referring to clinical, technical, and regulatory aspects. Thirty-one articles out of 81 found on the primary literature search were included in the systematic review. Most studies involved children with cerebral palsy. Only one-third of the studies were randomized controlled trials. Overall, 17 devices (nine end-effector systems and eight exoskeletons) were investigated, among which only 4 (24%) were bore the CE mark. Studies differ on rehabilitation protocols duration, intensity, and outcome measures. Future research should improve both rehabilitation protocols’ and devices’ descriptions.

Bilateral Asymmetry of Hand Force Production in Dynamic Physically-Coupled Tasks

Physically-coupled bimanual tasks (activities where a force effect occurs between two human limbs) involve the coordination and cooperation of bilateral arms. Such uncertain contribution of two arms is often studied under static configuration, which is not sufficient to typify all activities of daily life (ADLs). This study aims to investigate peoples bilateral force production and control in dynamic tasks. Experiments were conducted with a customized robotic system that is characterized with two handles and programmable force fields between them. Fourteen healthy right-handed human volunteers were instructed to generate force with each hand when performing predefined trajectory tracking tasks, in which the sum of forces contributed by the left and the right hand is required to equal a target force. Significant asymmetry was found in the force output between bilateral hands. With the homologous muscles activated synchronously, the contribution of the left hand was larger, while when the non-homogenous muscles were activated synchronously, the laterality was subject to the moving direction. In addition, when considering the force difference between two hands in terms of direction and magnitude, the former decreased with the increase of the target force, but the latter was more sensitive to moving directions. The results reveal the unique characteristics of non-isometric force control tasks compared with isometric ones.

Preliminary Assessment of a Postural Synergy-Based Exoskeleton for Post-Stroke Upper Limb Rehabilitation

Upper limb exoskeletons have drawn significant attention in neurorehabilitation because of the anthropomorphic mechanical structure analogous to human anatomy. Whereas, the training movements are typically unorganized because most exoskeletons ignore the natural movement characteristic of human upper limbs, particularly inter-joint postural synergy. This paper introduces a newly developed exoskeleton (Armule) for upper limb rehabilitation with a postural synergy design concept, which can reproduce activities of daily living (ADL) motion with the characteristics of human natural movements. The semitransparent active control strategy with the interactive force guidance and visual feedback ensured the active participation of users. Eight participants with hemiplegia due to a first-ever, unilateral stroke were recruited and included. They participated in exoskeleton therapy sessions for 4 weeks, with passive/active training under trajectories and postures with the characteristics of human natural movements. The primary outcome was the Fugl-Meyer Assessment for Upper Extremities (FMA-UE). The secondary outcomes were the Action Research Arm Test(ARAT), modified Barthel Index (mBI), and metric measured with the exoskeleton After the 4-weeks intervention, all subjects showed significant improvements in the following clinical measures: the FMA-UE (difference, 11.50 points, p = 0.002), the ARAT (difference, 7.75 points ), and the mBI (difference, 17.50 points, p = 0.003 ) score. Besides, all subjects showed significant improvements in kinematic and interaction force metrics measured with the exoskeleton. These preliminary results demonstrate that the Armule exoskeleton could improve individuals' motor control and ADL function after stroke, which might be associated with kinematic and interaction force optimization and postural synergy modification during functional tasks.

Validity, reliability, and sensitivity to motor impairment severity of a multi-touch app designed to assess hand mobility, coordination, and function after stroke

BACKGROUND

The assessment of upper-limb motor impairments after stroke is usually performed using clinical scales and tests, which may lack accuracy and specificity and be biased. Although some instruments exist that are capable of evaluating hand functions and grasping during functional tasks, hand mobility and dexterity are generally either not specifically considered during clinical assessments or these examinations lack accuracy. This study aimed to determine the convergent validity, reliability, and sensitivity to impairment severity after a stroke of a dedicated, multi-touch app, named the Hand Assessment Test.

METHODS

The hand mobility, coordination, and function of 88 individuals with stroke were assessed using the app, and their upper-limb functions were assessed using the Fugl-Meyer Assessment for Upper Extremity, the Jebsen-Taylor Hand Function Test, the Box and Block Test, and the Nine Hole Peg Test. Twenty-three participants were further considered to investigate inter- and intra-rater reliability, standard error of measurement, and the minimal detectable change threshold of the app. Finally, participants were categorized according to motor impairment severity and the sensitivity of the app relative to these classifications was investigated.

RESULTS

Significant correlations, of variable strengths, were found between the measurements performed by the app and the clinical scales and tests. Variable reliability, ranging from moderate to excellent, was found for all app measurements. Exercises that involved tapping and maximum finger-pincer grasp were sensitive to motor impairment severity.

CONCLUSIONS

The convergent validity, reliability, and sensitivity to motor impairment severity of the app, especially of those exercises that involved tapping and the maximum extension of the fingers, together with the widespread availability of the app, could support the use of this and similar apps to complement conventional clinical assessments of hand function after stroke.

Development of a Comprehensive Outcome Measure for Motor Coordination, Step 2: Reliability and Construct Validity in Chronic Stroke Patients

BACKGROUND

A comprehensive scale assessing motor coordination of multiple body segments was developed using a 3-phase content validation process. The Comprehensive Coordination Scale (CCS) evaluates motor coordination defined as the ability to produce context-dependent movements of multiple effectors in both spatial and temporal domains. The scale assesses motor coordination in individuals with neurological injuries at 2 levels of movement description: the motor performance level describes end point movements (ie, hand, foot), and the movement quality level describes limb joints/trunk movements contributing to end point movement.

OBJECTIVE

To determine measurement properties of the scale in people with chronic stroke.

METHODS

Standardized approaches determined the internal consistency (factor loadings), intrarater and interrater reliability (interclass correlation coefficient), measurement error (SEM; minimal detectable change [MDC]), construct validity, and interpretability (ie, ceiling and floor effects) of the CCS.

RESULTS

Data from 30 patients with chronic stroke were used for the analysis. The internal consistency of the scale was high (0.94), and the scale consisted of separate factors characterizing end point motor performance and movement quality. Intrarater (intraclass correlation coefficient [ICC] = 0.97-0.97) and interrater (ICC=0.76-0.98) reliability of the whole scale and subscales were good to excellent. The CCS had an SEM of 1.80 points (total score = 69 points) and an MDC₉₅ of 4.98 points. The CCS total score was related to Fugl-Meyer Assessment total and motor scores and had no ceiling or floor effects.

CONCLUSIONS

The CCS scale has strong measurement properties and may be a useful measure of spatial and temporal coordination deficits in chronic stroke survivors.

Development of a Comprehensive Outcome Measure for Motor Coordination; Step 1: Three-Phase Content Validity Process

BACKGROUND

Motor coordination, the ability to produce context-dependent organized movements in spatial and temporal domains, is impaired after neurological injuries. Outcome measures assessing coordination mostly quantify endpoint performance variables (ie, temporal qualities of whole arm movement) but not movement quality (ie, trunk and arm joint displacements).

OBJECTIVE

To develop an outcome measure to assess coordination of multiple body segments at both endpoint trajectory and movement quality levels, based on observational kinematics, in adults with neurological injuries.

METHODS

A 3-phase study was used to develop the Comprehensive Coordination Scale (CCS): instrument development, Delphi process, and focus group meeting. The CCS was constructed from common tests used in clinical practice and research. Rating scales for different behavioral elements were developed to guide analysis. For content validation, 8 experts (ie, neurological clinicians/researchers) answered questionnaires about relevance, comprehension, and feasibility of each test and rating scale. A focus group conducted with 6 of 8 experts obtained consensus on rating scale and instruction wording, and identified gaps. Three additional experts reviewed the revised CCS content to obtain a final version.

RESULTS

Experts identified a gap regarding assessment of hand/finger coordination. The CCS final version is composed of 6 complementary tests of coordination: finger-to-nose, arm-trunk, finger, lower extremity, and 2- and 4-limb interlimb coordination. Constructs include spatial and temporal variables totaling 69 points. Higher scores indicate better performance.

CONCLUSIONS

The CCS may be an important, understandable and feasible outcome measure to assess spatial and temporal coordination. CCS measurement properties are presented in the companion article.

Inherent Kinematic Features of Dynamic Bimanual Path Following Tasks

Bimanual coordination is critical in many robotic and haptic systems, such as surgical robots and rehabilitation robots. While these systems often incorporate two robotic manipulators for each limb, there may be a missed opportunity to leverage overarching models of human bimanual coordination to improve the way in which the robotic manipulators are controlled and respond to the dynamic human operator. In this paper, we study the influences of several bimanual motion factors (e.g., symmetry and direction) on kinematic human joint-space features and performance outcome task-space features in a user study with eleven subjects and two haptic devices. Additionally, we evaluated the ability to use joint-space features to classify types of bimanual movement, showing the potential for a robotic system to predict how users coordinate their limbs. Three classifiers: (1) likelihood ratio, (2) k-nearest neighbor, and (3) support vector machine, were evaluated for classification accuracy in regards to the factor of number of targets. Likelihood ratio resulted in an accuracy of 79.6% with the majority of correct predictions occurring immediately at the start of movement. The task-space performance results reveal that despite the relative direction of both hands, reaching two targets results in lower performance than a single target, and symmetry alone does not contribute to performance disparity. Also, dimensionless integrated absolute jerk (DIAJ) is an indicator of superior performance for this particular task. Furthermore, these results align with current bimanual coordination theory by showing manual performance disparities are a consequence of task constraints and conceptualization.

Assessment of bimanual proprioception during an orientation matching task with a physically coupled object

Assessing proprioception is important for understanding and treating sensorimotor impairments. Many daily tasks require bimanual manipulation of objects, but state of the art methods for the assessment of proprioception are far away from bimanual activities, and instead evaluate sensorimotor integrity in oversimplified and often unimanual goal-directed tasks. Here, we developed a new device and method to assess proprioception and force production by simulating a realistic bimanual behavior. Twelve healthy participants held a physically coupled object - a sensorized box - and matched target orientations about the three principal axes without and with added weights. Our preliminary findings indicate that bimanual proprioception during orientation matching depends on the axis of rotation. For example, in rotations about the lateral axis of the body, underestimation and overestimation of the target angle depends on its orientation in a body-centered reference frame: participants tended to underestimate targets that required rotation far away from the body and overestimated angles that required rotation towards the body. We also found that for the same rotation axis, the larger were the rotations, the higher was the force applied. Moreover, we also found that fatigue causes undershoot in orientation matching. In the future, this tool could be adopted for assessment and treatment of sensorimotor deficits in bimanual functional tasks.

Interlimb coupling in poststroke rehabilitation: a pilot randomized controlled trial

Background: The interlimb coupling, coordination between the limbs, gets hampered in post-stroke hemiparesis. Most of the poststroke motor regimes primarily focus on the more affected limb.Objectives: To develop an interlimb coupling protocol and assess its feasibility and effect on motor recovery, gait and disability among post-stroke subjects.Design: A pilot randomized controlled, doubled blinded trialSetting: A rehabilitation instituteMethods: 50 post-stroke (> 6 months) hemiparetic subjects (Brunnstrom recovery stage ≥ 3) were randomly divided into experimental (n=26) and control (n=24) groups. The 8-week experimental intervention (3 sessions of 1 hour each, per week) comprised activities demanding coordinated, alternate, and rhythmic use of the affected as well as the less-affected limbs. The outcome measures were feasibility of activities, Fugl-Meyer assessment (FMA), Rivermead visual gait assessment (RVGA), Functional ambulation category (FAC) and modified Rankin scale (mRS).Results: The experimental protocol was found to be feasible by the participants. Post intervention, the experimental group exhibited highly significant difference for FMA (mean difference = 7.12, 95% CI = 5.71 - 8.53, p < 0.001), RVGA reduction (mean difference = - 6.32, 95% CI = 7.51 - 5.13, p < 0.001), and median FAC enhancement (p < 0.001) in comparison to the controls. However, the median mRS level of experimental group did not change significantly (p = 0.056) when compared with the controls.Conclusions: The interlimb coupling training, a feasible program may enhance recovery of the upper and lower limbs and gait in stroke. Further definitive randomized trials are warranted to validate the present findings.

Assessment of body-powered 3D printed partial finger prostheses: a case study

BACKGROUND

Traditional prosthetic fabrication relies heavily on plaster casting and 3D models for the accurate production of prosthetics to allow patients to begin rehabilitation and participate in daily activities. Recent technological advancements allow for the use of 2D photographs to fabricate individualized prosthetics based on patient anthropometrics. Additive manufacturing (i.e. 3D printing) enhances the capability of prosthesis manufacturing by significantly increasing production speed and decreasing production cost. Existing literature has extensively described the validity of using computer-aided design and 3D printing for fabrication of upper limb prostheses. The present investigation provides a detailed description of the development of a patient specific body-powered 3D printed partial finger prosthesis and compares its qualitative and functional characteristics to a commercially available finger prosthesis.

CASE PRESENTATION

A 72-year old white male with a partial finger amputation at the proximal interphalangeal joint of the left hand performed a simple gross motor task with two partial finger prostheses and completed two self-reported surveys (QUEST & OPUS). Remote fitting of the 3D printed partial finger began after receipt of 2D photographs of the patient's affected and non-affected limbs. Prosthetic fitting when using 3D printable materials permitted the use of thermoforming around the patient's residual limb, allowing for a comfortable but tight-fitting socket. Results of the investigation show improved performance in the Box and Block Test when using both prostheses (22 blocks per minute) as compared to when not using a prosthesis (18 blocks per minute). Both body-powered prostheses demonstrated slightly lower task-efficiency when compared to the non-affected limb (30 blocks per minute) for the gross motor task. Results of the QUEST and OPUS describe specific aspects of both prostheses that are highly relevant to quality of life and functional performance when using partial finger prostheses.

CONCLUSION

The use of 3D printing exhibits great potential for the fabrication of functional partial finger prostheses that improve function in amputees. In addition, 3D printing provides an alternative means for patients located in underdeveloped or low-income areas to procure a functional finger prosthesis.

Technology-aided assessments of sensorimotor function: current use, barriers and future directions in the view of different stakeholders

BACKGROUND

There is growing interest in the use of technology in neurorehabilitation, from robotic to sensor-based devices. These technologies are believed to be excellent tools for quantitative assessment of sensorimotor ability, addressing the shortcomings of traditional clinical assessments. However, clinical adoption of technology-based assessments is very limited. To understand this apparent contradiction, we sought to gather the points-of-view of different stakeholders in the development and use of technology-aided sensorimotor assessments.

METHODS

A questionnaire regarding motivators, barriers, and the future of technology-aided assessments was prepared and disseminated online. To promote discussion, we present an initial analysis of the dataset; raw responses are provided to the community as Supplementary Material. Average responses within stakeholder groups were compared across groups. Additional questions about respondent's demographics and professional practice were used to obtain a view of the current landscape of sensorimotor assessments and interactions between different stakeholders.

RESULTS

One hundred forty respondents from 23 countries completed the survey. Respondents were a mix of Clinicians (27%), Research Engineers (34%), Basic Scientists (15%), Medical Industry professionals (16%), Patients (2%) and Others (6%). Most respondents were experienced in rehabilitation within their professions (67% with > 5 years of experience), and had exposure to technology-aided assessments (97% of respondents). In general, stakeholders agreed on reasons for performing assessments, level of details required, current bottlenecks, and future directions. However, there were disagreements between and within stakeholders in aspects such as frequency of assessments, and important factors hindering adoption of technology-aided assessments, e.g., Clinicians' top factor was cost, while Research Engineers indicated device-dependent factors and lack of standardization. Overall, lack of time, cost, lack of standardization and poor understanding/lack of interpretability were the major factors hindering the adoption of technology-aided assessments in clinical practice. Reimbursement and standardization of technology-aided assessments were rated as the top two activities to pursue in the coming years to promote the field of technology-aided sensorimotor assessments.

CONCLUSIONS

There is an urgent need for standardization in technology-aided assessments. These efforts should be accompanied by quality cross-disciplinary activities, education and alignment of scientific language, to more effectively promote the clinical use of assessment technologies.

TRIAL REGISTRATION

NA; see Declarations section.

The effects of speed of execution on upper-limb kinematics in activities of daily living with respect to age

In this study, 26 young, 16 older adults ≤ 66a, and 22 older adults ≥ 67a were examined in a set of neuropsychological tests and the kinematics in two different activities of daily living (ADL) were assessed. Half of the participants performed the ADL in a natural speed, the other half as fast as possible. The performance in the Trail Making Task B revealed an increased slope after 67 years of age. When executed in a natural speed, ADL kinematics were comparable. When executed as fast as possible, almost all kinematic parameters showed significant group and speed differences and revealed group × speed interactions. Models of multiple linear regression predicting ADL trial durations showed similar strategies in the young and older adults < 67a. Factors were the general movement speed, the travelled path lengths, and the simultaneous use of both hands. In the older adults ≥ 67a, factors were the general movement speed, the travelled path length, and the activity level (during the task execution). A principal component analysis supported these findings by revealing two underlying components: movement strategy and age-dependent decline in primarily executive functions, where the ADL trial duration had comparable loadings on both components. These results in association with the accelerated decline in executive functions found in the oldest group suggest that deterioration of ADL with age is particularly caused by specific age-dependent changes in cognitive capacities.

Bimanual coordination during a physically coupled task in unilateral spastic cerebral palsy children

Background

Single object bimanual manipulation, or physically-coupled bimanual tasks, are ubiquitous in daily lives. However, the predominant focus of previous studies has been on uncoupled bimanual actions, where the two hands act independently to manipulate two disconnected objects. In this paper, we explore interlimb coordination among children with unilateral spastic cerebral palsy (USCP), by investigating upper limb motor control during a single object bimanual lifting task.

Methods

15 children with USCP and 17 typically developing (TD) children performed a simple single-object bimanual lifting task. The object was an instrumented cube that can record the contact force on each of its faces alongside estimating its trajectory during a prescribed two-handed lifting motion. The subject’s performance was measured in terms of the duration of individual phases, linearity and monotonicity of the grasp-to-load force synergy, interlimb force asymmetry, and movement smoothness.

Results

Similar to their TD counterparts, USCP subjects were able to produce a linear grasp-to-load force synergy. However, they demonstrated difficulties in producing monotonic forces and generating smooth movements. No impairment of anticipatory control was observed within the USCP subjects. However, our analysis showed that the USCP subjects shifted the weight of the cube onto their more-abled side, potentially to minimise the load on the impaired side, which suggests a developed strategy of compensating for inter-limb asymmetries, such as muscle strength.

Conclusion

Bimanual interaction with a single mutual object has the potential to facilitate anticipation and sequencing of force control in USCP children unlike previous studies which showed deficits during uncoupled bimanual actions. We suggest that this difference could be partly due to the provision of adequate cutaneous and kinaesthetic information gathered from the dynamic exchange of forces between the two hands, mediated through the physical coupling.

Motion Tracking for Quantitative and Qualitative Assessment of Upper Limb Movements Following Acromioclavicular Joint Ligament Reconstruction: A Pilot Study

Background:

Technological tools as robotic devices and wearable sensors can provide accurate and repeatable measurements of physical variables (e.g., position, velocities, forces) which can be used for quantitative and qualitative assessment of movement analysis and upper limb motor performance.

Objective:

The study aims to propose a quantitative and qualitative assessment of upper limb motor performance by means of seven kinematic parameters recorded by a passive mechatronic device in patients who underwent a surgical procedure for ligament reconstruction following acromioclavicular joint dislocation.

Method:

Five patients (mean age: 40 ± 12 years) with acromioclavicular joint dislocation were enrolled.

A passive end-effector mechatronic device characterized by 7 degrees of freedom and designed for the assessment of upper limb motor performance - especially for measuring the hand position in three-dimensional space - was used.

The Constant-Murley score and seven kinematic parameters were used as clinical outcome measure and quantitative and qualitative assessment, respectively.

Results:

The preliminary results of this study show no significant differences between the impaired arm and unimpaired arm: the end-effector passive mechatronic device used in this study is able to provide an overall assessment of the upper limb motor performance following shoulder impairment.

Conclusion:

The motion tracker can be easily used as effective tool for quantitative and qualitative assessment of upper limb motor performance, even several years after the surgical operation.

Upper limb robot-assisted therapy in subacute and chronic stroke patients using an innovative end-effector haptic device: A pilot study

BACKGROUND

Significant results have been shown when an upper limb robot-assisted rehabilitation is delivered to stroke patients.

OBJECTIVE

To evaluate the effects of upper limb robot-assisted rehabilitation on motor recovery in stroke patients who underwent a treatment based on a haptic device.

METHODS

Thirty-nine stroke patients (twenty-three subacute and sixteen chronic) underwent rehabilitation training by using MOTORE/Armotion haptic system. Thirteen healthy subjects were recruited for comparison purpose.The following clinical outcome measures were used: Chedoke-McMaster Stroke Assessment, Modified Ashworth Scale (MAS), Fugl-Meyer Assessment (FM), Medical Research Council, Motricity Index (MI), Box and Block Test (B&B) and Modified Barthel Index (mBI).The following parameters were computed: mean speed, maximum speed, mean time, path length, normalized jerk, mean force, mean error, mean energy expenditure and active patient-robot interaction percentage.The assessments were carried-out before and after treatment.

RESULTS

Significant changes were observed in both groups in the FM, MI, B&B and mean speed. Significant changes were observed in mBI, mean time, mean force, mean energy expenditure and active patient-robot interaction percentage in subacute stroke patients. In chronic stroke patients significant changes were found on the MAS-elbow.

CONCLUSIONS

The haptic device used is at least as effective as an existing device used in similar studies.

Bimanual coordination: A missing piece of arm rehabilitation after stroke

Inability to use the arm in daily actions significantly lowers quality of life after stroke. Most contemporary post-stroke arm rehabilitation strategies that aspire to re-engage the weaker arm in functional activities have been greatly limited in their effectiveness. Most actions of daily life engage the two arms in a highly coordinated manner. In contrast, most rehabilitation approaches predominantly focus on restitution of the impairments and unilateral practice of the weaker hand alone. We present a perspective that this misalignment between real world requirements and intervention strategies may limit the transfer of unimanual capability to spontaneous arm use and functional recovery. We propose that if improving spontaneous engagement and use of the weaker arm in real life is the goal, arm rehabilitation research and treatment need to address the coordinated interaction between arms in targeted theory-guided interventions. Current narrow focus on unimanual deficits alone, difficulty in quantifying bimanual coordination in real-world actions and limited theory-guided focus on control and remediation of different coordination modes are some of the biggest obstacles to successful implementation of effective interventions to improve bimanual coordination in the real world. We present a theory-guided taxonomy of bimanual actions that will facilitate quantification of coordination for different real-world tasks and provide treatment targets for addressing coordination deficits. We then present evidence in the literature that points to bimanual coordination deficits in stroke survivors and demonstrate how current rehabilitation approaches are limited in their impact on bimanual coordination. Importantly, we suggest theory-based areas of future investigation that may assist quantification, identification of neural mechanisms and scientifically-based training/remediation approaches for bimanual coordination deficits post-stroke. Advancing the science and practice of arm rehabilitation to incorporate bimanual coordination will lead to a more complete functional recovery of the weaker arm, thus improving the effectiveness of rehabilitation interventions and augmenting quality of life after stroke.

Combining Upper Limb Robotic Rehabilitation with Other Therapeutic Approaches after Stroke: Current Status, Rationale, and Challenges

A better understanding of the neural substrates that underlie motor recovery after stroke has led to the development of innovative rehabilitation strategies and tools that incorporate key elements of motor skill relearning, that is, intensive motor training involving goal-oriented repeated movements. Robotic devices for the upper limb are increasingly used in rehabilitation. Studies have demonstrated the effectiveness of these devices in reducing motor impairments, but less so for the improvement of upper limb function. Other studies have begun to investigate the benefits of combined approaches that target muscle function (functional electrical stimulation and botulinum toxin injections), modulate neural activity (noninvasive brain stimulation), and enhance motivation (virtual reality) in an attempt to potentialize the benefits of robot-mediated training. The aim of this paper is to overview the current status of such combined treatments and to analyze the rationale behind them.