Posts Tagged upper limb

[WEB] FDA Expands Botox Approval for Upper Limb Spasticity in Adults

FDA Expands Botox Approval for Upper Limb Spasticity in Adults

The U.S. Food and Drug Administration (FDA) has approved a label expansion of BOTOX to include eight new muscles for the treatment of upper limb spasticity in adults, Allergan, an AbbVie company, announces in a media release.

The new muscles for treatment include additional muscles of the elbow and forearm (brachialis, brachioradialis, pronator teres, and pronator quadratus), as well as intrinsic hand muscles (lumbricals and interossei) and thumb muscles (flexor pollicis brevis and opponens pollicis). The label now includes the use of ultrasound as a muscle localization technique in adult spasticity, the release explains.

“Today’s announcement is especially important because spasticity is a disabling neurological condition that can have a significant impact on a patient’s quality of life. This label expansion not only adds to our rich history in neurotoxin science, but also reinforces the role of BOTOX in upper limb spasticity treatment. BOTOX provides an evidence-based dosing strategy to meet the clinical needs of providers and their patients.”

— Mitchell F. Brin, MD, Senior Vice President, Chief Scientific Officer, BOTOX & Neurotoxins, AbbVie

Helps Reduce Muscle Stiffness

Spasticity in adults is commonly caused by stroke, multiple sclerosis, spinal cord injury, cerebral palsy, and traumatic brain injury. Individuals with spasticity experience stiffness in the muscles of their upper and/or lower limbs, and may have difficulty with voluntary control. Upper limb spasticity can manifest as a bent elbow, an arm pressed against the chest, or a curled-in hand with a clenched fist, significantly hindering the patient’s ability to perform everyday activities. This can result in difficulty with posture and positioning, and severely interfere with normal muscular movement and function.

BOTOX has been proven to significantly reduce muscle stiffness and is indicated for the treatment of spasticity in patients 2 years of age and older. This expanded BOTOX dosing guidance provides physicians the ability to treat based on clinical assessment of a patient’s spasticity and anatomy while staying within the BOTOX maximum cumulative dose of 400 Units in a 3-month period in adults. BOTOX has not been shown to improve upper extremity functional abilities or range of motion at a joint affected by a fixed contracture. The safety profile of BOTOX in adult upper limb spasticity remains the same, with the most common adverse reactions including nausea, fatigue, bronchitis, pain in extremity and muscular weakness, the release continues.

“BOTOX has demonstrated efficacy and safety for spasticity management at clinically proven doses. This label expansion offers physicians and their patients living with spasticity another important tool as part of a comprehensive treatment plan for spasticity management.”

— Kimberly Heckert, MD, Director, Spasticity Management Fellowship, Thomas Jefferson University of Philadelphia


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[Abstract] A Review: Hand Exoskeleton Systems, Clinical Rehabilitation Practices, and Future Prospects


Spinal cord injury (SCI) and stroke are pathologies that often result in the loss of/decrease in hand functionality. Hand function is a critical component of everyday life and therefore, a primary focus of clinical SCI/stroke rehabilitation is hand function recovery/improvement. In recent years, there has been a surge in hand exoskeleton research due to the potential for exoskeletons to improve clinical rehabilitation efficiency through automation. However, there is a disconnect between current clinical practice and exoskeleton research, resulting in a minority of hand exoskeletons being tested on individuals with SCI and/or stroke. This review article provides a comprehensive analysis and review of hand exoskeleton studies based on clinical rehabilitation practices to bridge the knowledge gap between clinical application and laboratory research. The key findings from this paper are: 1) current hand exoskeletons can successfully complete simple ADL tasks but lack the precision for fine motor control, 2) most hand exoskeletons exhibit a low number of degrees-of-freedom compared to the human hand, which may limit movement capability, 3) the majority of hand exoskeletons lack sensing capabilities, restricting viable control methods and user interfaces, and 4) inconsistent evaluation methods across studies do not allow for accurate performance assessment for different exoskeletons. The comparative assessments performed by this survey article show that there remain deficits between clinical hand rehabilitation practices and the current state of hand exoskeletons. By delineating these shortcomings, the information presented in this work can help inform future developments in the field of assistive and rehabilitative hand exoskeletons such that the gap between research and application may be closed.

Published in: IEEE Transactions on Medical Robotics and Bionics ( Early Access )

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[Abstract+References] Fatigue-aware videogame using biocybernetic adaptation: a pilot study for upper-limb rehabilitation with sEMG

extended data figure 2


Physical rehabilitation has been widely used to restore or maintain motor capabilities of patients with upper-limb mobility limitations. Despite its effectiveness, physical rehabilitation has several difficulties in engaging patients with the multiple therapeutical sessions required to obtain measurable benefits. Novel technologies incorporate gamification strategies to encourage participants to play during the rehabilitation sessions (instead of counting repetitions), providing benefits for therapy adherence. “Serious” or also called applied games have been used as a complementary therapy for neuromuscular disorders. However, the therapy effectiveness of several serious games for health has been questioned by the clinical experts since crucial factors associated with the physical rehabilitation are not commonly included in the gameplay. This study reports the use of a physiologically aware serious game developed using surface electromyography (sEMG) to capture upper-limb muscular fatigue levels of participants. We carried out a pilot study lasting four weeks with five participants diagnosed with monoparesis/hemiparesis to evaluate the feasibility of using the fatigue-adaptive game called Force Defense as a complementary tool for physical rehabilitation in a local community-based rehabilitation center. Preliminary results suggest a positive user gameplay experience as well as good usability of the system reported by participants after the first intervention session. Moreover, we showed how the physiological adaptation was able to encourage participants to maintain exertion in the therapeutically desired zone, thus improving the system’s effectiveness. Participants also improved in their functional abilities of the upper limbs and the game performance measured in pre- and post-moments and reported reduced levels of perceived fatigue after the end of the training program.


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[Abstract] Effects of Robot-assisted Upper Extremity Rehabilitation on Change in Functioning and Disability in Patients With Neurologic Impairment: A Pilot Study – Full Text PDF


Introduction: The aim is to evaluate the effect of robot-assisted training on the most important aspects of functioning and disability in patients with upper extremity neurologic impairment.

Materials and Methods: A prospective six-week pilot study included robot-assisted training of the upper extremity and conventional neurorehabilitation in 12 participants after a stroke or traumatic brain injury. Outcome measurements were range of motion (ROM), the International Classification of Functioning, Disability and Health (ICF) Core Set for Hand and the Visual Analog Scale (VAS) for pain sensation. A Wilcoxon test was used for the analysis of pre- and post-test differences and Spearman’s correlation was used for connecting the data collected.

Results: A statistically significant difference was found for ROM (shoulder abduction/adduction, shoulder flexion/extension, shoulder internal/external rotation and forearm pronation/supination) and a number of ICF categories (Body Function: b280, b710, b715, b730, b760; Activities and Participation: d230, d430, d440, d445, d5). A significant positive correlation of medium intensity (r=0.589) was found between the duration of movement coordination training and the ICF category b760. We did not find a statistically significant difference in pain sensation (VAS) with regard to the direct use of the device. For all analyses, p<0.05 and CI was 95%.

Conclusion: Robot-assisted training and conventional neurorehabilitation improved motor and functional recovery. There was a correlation between training a specific goal on the device and one of the ICF Body Function categories.

Full Text PDF


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[ARTICLE] Effects of Specific Virtual Reality-Based Therapy for the Rehabilitation of the Upper Limb Motor Function Post-Ictus: Randomized Controlled Trial – Full Text


This research analyzed the combined effect of conventional treatment and virtual reality exposure therapy on the motor function of the upper extremities in people with stroke. We designed a randomized controlled trial set in the rehabilitation and neurology departments of a hospital (Talavera de la Reina, Spain). The subjects included 43 participants, all randomized into experimental (conventional treatment + virtual reality exposure therapy) and control group (conventional treatment).; The main measures were Fugl-Meyer Assessment for upper extremity, Modified Ashworth Scale, and Stroke Impact Scale 3.0. The results included 23 patients in the experimental (62.6 ± 13.5 years) and 20 in the control group (63.6 ± 12.2 years) who completed the study. After the intervention, muscle tone diminished in both groups, more so in the experimental group (mean baseline/post-intervention: from 1.30 to 0.60; η2 = 0.237; p = 0.001). Difficulties in performing functional activities that implicate the upper limb also diminished. Regarding the global recovery from stroke, both groups improved scores, but the experimental group scored significantly higher than the controls (mean baseline/post-intervention: from 28.7 to 86.5; η2 = 0.633; p = 0.000). In conclusion, conventional rehabilitation combined with specific virtual reality seems to be more efficacious than conventional physiotherapy and occupational therapy alone in improving motor function of the upper extremities and the autonomy of survivors of stroke in activities of daily living.

1. Introduction

Stroke is one of the main causes of acquired disability in adulthood. The stroke epidemic is primarily driven by the aging of the world population, globalization and the urbanization of community settings [1,2]. The Stroke Alliance for Europe states that, every 20 s, a new case of stroke is detected in the adult population and predicts that the number of people affected will increase by 35% to 12 million people in 2040. As a result, it is estimated that the health and social costs for stroke diagnosis will increase to 75 million in 2030 (26% more than in 2017). In Spain, 550,941 people were diagnosed with stroke in 2017, generating a health expenditure of 1700 million euros and a total cost to the Spanish state of 3557 million euros [3].Around 80% of survivors present motor difficulties in the upper extremities, affecting the carrying out of activities of daily living (ADLs), the performance of roles in the community and the health-related quality of life (HRQoL) [4,5,6].Complications after stroke diagnosis can persist over time. Two-thirds of survivors are disabled 15 years later, two out of five are immersed in depressive states and more than a quarter develop cognitive impairment [7]. The costs derived from stroke diagnosis are high for survivors and their families, making their rehabilitation and survival processes a great challenge for health policymakers [8,9]. On average, an informal (non-professional) caregiver in Spain invests 2833 h per year in caring for the person affected by stroke and with limitations in ADLs [3].The general objective of neurological rehabilitation is to promote a rapid recovery from the multiple deficits after a stroke and the achievement of a lifestyle similar to the premorbid state [10,11]. Of all people diagnosed with stroke, only 30–40% regain certain skills in the upper limb after six months of intervention [12]. The upper limb remains non-functional for ADLs in up to 66% of survivors [13], constituting the most disabling of all residual disorders.In recent years, the use of neurorehabilitation approaches based on technology and virtual reality has increased, allowing the creation of effective rehabilitation environments and providing multimodal, controllable, and customizable stimulation [14], in which the recreation of virtual objects maximize visual feedback [15] and high intensity and high number of repetitions are key factors that influence neuroplasticity and functional improvement in patients [16]. Rehabilitation based on virtual reality offers the possibility of individualizing treatment needs, and at the same time, standardizing evaluation and training protocols [17,18]. In this sense, specific virtual reality technology for rehabilitation processes of people with neurological pathology allows working in a functional way and with specific intervention objectives, in addition to easily qualifying and documenting progress during the session [19]. Taking advantage of these characteristics, several researchers have used virtual reality exposure therapy (VRET) to recover motor function after stroke. In the treatment of the upper limb, studies indicate that this rehabilitation approach produces better motor and functional results than conventional therapy [20,21].The increasing clinical use of neurorehabilitation approaches based on technology and virtual reality leads to the assumption that spatial representations in virtual environments may vary slightly from the perceptions that the patient would experience in real spaces. In this sense, the team of Hruby et al. [22] insisted that spatial representations based in virtual reality systems should be realistic 1:1 replicas with regard to the individual characteristics of the subjects interacting with both virtual and real environments. This demand increases the validity of virtual reality techniques for therapeutic purposes, since interaction with a virtual space is safer and more profitable in the early phases of rehabilitation processes [23]. However, it is important for clinicians and researchers to consider that the interaction with a virtual environment continues to be different from the relationship that the subject maintains with the real environment [24] because people gradually build a mental representation of the geographic space that we work with or are immersed in. The locomotion techniques applied in the virtual model (software or hardware) can influence the cognitive representations of the person experiencing them [25].The present study aimed to analyze the combined effect of conventional treatment and VRET on motor function of the upper limb in people diagnosed with stroke in the acute phase and its evolution at three months in the Integrated Health Area of Talavera de la Reina.[…]


Figure 1. (a) Selection of analytical exergames; (b) selection of functional exergames; (c) adaptation of exergames at the beginning of a treatment session; (d) graphical representation of results or progress of the patient.

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[ARTICLE] Design of a 3D printed hybrid mechanical structure for a hand exoskeleton – Full Text

By Jens Vertongen and Derek Kamper


Stroke survivors often have difficulty performing activities of daily living (ADLs) due to hand impairments. Several assistive devices have been developed for stroke survivors to assist them with ADLs but most of these devices are difficult to don and doff for a stroke survivor due to highly flexed postures of the wrist and digits. This paper presents a hybrid 3D printed mechanical structure for an assistive hand exoskeleton created for stroke survivors. The design facilitates donning and doffing of the assistive exoskeleton by enabling an approach entirely from the dorsal side of the hand, thereby allowing the fingers to stay flexed. The design criteria, resulting design and the prototype development are presented. The initial prototype of the structure, using a hybrid combination of rigid and flexible materials, was lightweight (only 185 g), while maintaining a high range of motion. Future directions for further improvements and user studies are described.


Stroke often results in a severe impairment of the upper limb, particularly the distal segment, in stroke survivors. In 2010 there were 6.7 million stroke survivors in the United States alone, with 795,000 new or recurring strokes occurring each year [1]. The symptoms of this impairment include paresis, involuntary muscle contraction patterns and impaired movements of the paretic hand [2]. These can make it difficult for stroke survivors to perform activities of daily living (ADLs) such as eating, bathing and dressing. Therefore, an assistive device for the distal upper limb that can assist with these activities has the potential to improve the stroke survivor’s quality of life.

Several assistive devices have been reported in literature. These devices commonly use a rigid structure [3], [4], [5] or a glove that routes tendons along the fingers [6], [7], [8]. These devices are often difficult to don and doff due to the typically flexed hand posture and the lack of voluntary finger extension. Coupling an assistive device to a stroke survivor’s hand can be especially challenging, due to the limited available contact area on the digits and the substantial resistance to even passive extension of the digits that arises from involuntary muscle activation [9].

In this paper we present the design of a hybrid, 3D printed mechanical structure of a hand exoskeleton intended to actuate the fingers of stroke survivors. The aim is to improve the donning process while providing the capability of both flexion and extension assistance from a single actuator for each finger located on the dorsal side of the hand. The actuator drives push-pull cables that can either flex or extend the joints of the digit. Thus, the mechanical structure, composed of rigid and flexible materials, must serve as the interface between the actuator and the digit.

Design requirements

The exoskeleton structure must fulfill multiple roles: guiding the cables actuating the hand, transmitting moments to the fingers and thumb, and preventing excessive joint rotation. The design requirements are listed in the following three categories: structural, safety and transmission requirements.

Structural requirements

The device has to fit the hand of the user while maintaining a low profile (maximum height of 25 mm above the finger) and should be easy to don and doff. The structure has to guide the push-pull cables and should keep the palmar surface free and accessible to minimize interference with the user’s sensory feedback and manipulation of objects. The device has to be lightweight with a mass under 300 g. The range of motion (ROM) of the hand with the device should be close to the normal ROM: 100, 105 and 85° for the MCP, PIP and DIP respectively and 56 (MCP) and 73° (IP) for the thumb [10]. Furthermore, the fingers should be able to abduct.

Safety requirements

The mechanical structure should prevent excessive joint flexion and extension. Moving parts have to be shielded to prevent tissue or body parts to be pinched.

Transmission requirements

Ultimately, the structure has to transmit the moments from the cables to the finger joints. The friction between the cables and the guides should be as low as possible.

Exoskeleton structure design

Full structure

The structure was designed through an iterative process of 3D design, rapid prototyping and verification. Drawing on hand dimensions from the literature [11], we designed a prototype using 3D CAD software (Figure 1). The mechanical structure is a hybrid design of rigid components, attached to the digit segments that guide the cables and prevent excessive joint rotation, and a flexible inner lining that connects the rigid components and improves comfort and functionality. The exoskeleton can be donned entirely from the dorsal side of the hand, with the rigid pieces deforming to accommodate the finger, thereby generating a clamping force against the sides of the finger. The structure extends to the forearm in order to provide bracing to maintain the wrist in a functional extended posture. This splint structure also provides housing for the actuators and electronics. Straps around the hand and wrist help to secure the location of the device on the body.

Figure 1: Full overview of the mechanical structure in red with the flexible lining in gray and actuators in black. Top: dorsal view. Bottom: palmar view.

Figure 1:

Full overview of the mechanical structure in red with the flexible lining in gray and actuators in black. Top: dorsal view. Bottom: palmar view.

Finger structure

The anatomical differences in the distal phalanx (DP) of the thumb and the pinky finger, in comparison with the index, middle and ring fingers, require a different form factor for these segments (see Figure 1). We employed conical shapes for the components of the intermediate phalanx (IP) to ensure proper fitting on the finger segment.

Adjacent cable-guide segments meet during joint extension to prevent hyperextension of the joints (Figure 2). To prevent hyperflexion of the joints, possible pinching and buckling of the cable, we attached a fabric sleeve at the ends of the cable guides around the wire. These fabrics clamp over the conical end and are secured with a metal ring (Figure 3).

Figure 2: The structure of one finger.

Figure 2:

The structure of one finger.

Figure 3: Detail of the sleeves preventing cable buckling.

Figure 3:

Detail of the sleeves preventing cable buckling.

The cable guides on the dorsal side of the fingers are easily customizable to achieve different moment arms around the joints. We used two cables for a better lateral stability to actuate the fingers. The friction of the cable, governed by the capstan Equation (1), should be minimized [12].(1)Tout= e−μϕTinTout= e−μϕ Tin

In Equation (1)μ is the friction coefficient and ϕ is the deflection angle of the cable segment that is sliding in the tube. We designed the path inside the rigid component with the smallest curvature possible in order to minimize friction along the cable. Figure 4 shows a section of the finger structure where the cable path is visible.

Figure 4: Section of the index finger showing the path of the cable within the guide.

Figure 4:

Section of the index finger showing the path of the cable within the guide.

The push-pull cable locks in the front of the structure in a groove above the DP (see Figure 3). This groove facilitates the assembly of the cable in the structure. The recess in this groove permits easy removal of the cable with a screwdriver.

Arm structure

The arm structure supports the actuators, transmission and electronics, in addition to maintaining a neutral wrist posture (see Figure 5). Velcro straps around the hand, wrist and forearm secure the location on the arm. We placed the actuators locally, on the forearm, to avoid frictional losses inherent to the use of long Bowden cables needed with remotely placed actuators.

Figure 5: The arm structure that supports the actuators. Motors and cables are represented with transparent bodies.

Figure 5:

The arm structure that supports the actuators. Motors and cables are represented with transparent bodies.

Prototype development

The final prototype, realized with acrylonitrile butadiene styrene (ABS) and thermoplastic polyurethane (TPU) through 3D printing, proved to be lightweight and comfortable. The mass of the entire mechanical structure was only 185 g. The distal portion that actually moves with the fingers and thumb was 82 g in total, or an average of roughly 16 g per digit; the forearm brace accounts for the other 103 g. The ROM of the fingers, while wearing the structure when not actuated, is very close to the normal ROM (see Table 1). The finger structures in black and the arm structure in white are shown in Figure 6.Table 1:Weight and ROM of the prototype.


82 g
Arm part

103 g

185 g
ROMMCP (°)PIP (°)DIP (°)
Index finger808575
Middle finger859575
Ring finger909575
Pinky finger758575
Normal ROM thumb5673
Normal ROM finger10010585
Figure 6: The final prototype.

Figure 6:

The final prototype.

3D printing and material selection

We used 3D printing as a rapid prototyping method to produce the exoskeleton structure due to the various benefits such as easily available, quick and the ability to produce complex shapes.

The structure was produced with two different 3D printers. The rigid and flexible material of the finger structures was produced by the BCND Sigma R17 3D printer. The rigid material of the arm structure was printed by the Stratasys Dimension 1200 3D printer that has a larger build volume to produce the arm structure.

We employed ABS to produce the rigid components. This material was selected rather than polylactic acid (PLA) due to its greater toughness. A more flexible material, TPU, was chosen for the liner.


The weight and the range of motion of the exoskeleton are important for the functionality and comfort for the user. Table 1 lists the weight and the range of motion of the exoskeleton. The normal ROM values of the thumb and the fingers [10] are shown for reference. The exoskeleton proved to be comfortable to wear for extended periods of time. This was tested for a period of 1 h of use by one of the authors while performing ADLs. No pain or discomfort was reported for the duration of the test. Due to the large range of motion and slim profile, the author was able to grasp most everyday objects. There was some minor discomfort in pronation and supination, however, due to the location of the structure on the forearm.


An actuated hand exoskeleton has the potential to improve the quality of life for stroke survivors by assisting with ADLs. The lightweight mechanical structure developed in this study helps to make such a device possible. Easily customizable to the shape of the user’s hand, the structure can accommodate the push-pull cables used to drive the fingers while preventing joint hyperextension. The ability to put on the device entirely from the dorsal side of the hand greatly improves donning for stroke survivors with a flexed resting posture and resistance to passive extension. The slim profile, high range of motion and low mass result in a functional and comfortable structure.

The major limitation of the current structure is the TPU used for the flexible liner. A material with greater elasticity could be better suited for the application and could improve user comfort. Further development of the design and user testing are needed to improve and validate the design.


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[ARTICLE] Peak Activation Shifts in the Sensorimotor Cortex of Chronic Stroke Patients Following Robot-assisted Rehabilitation Therapy – Full Text



Ischemic stroke is the most common cause of complex chronic disability and the third leading cause of death worldwide. In recovering stroke patients, peak activation within the ipsilesional primary motor cortex (M1) during the performance of a simple motor task has been shown to exhibit an anterior shift in many studies and a posterior shift in other studies.


We investigated this discrepancy in chronic stroke patients who completed a robot-assisted rehabilitation therapy program.


Eight chronic stroke patients with an intact M1 and 13 Healthy Control (HC) volunteers underwent 300 functional magnetic resonance imaging (fMRI) scans while performing a grip task at different force levels with a robotic device. The patients were trained with the same robotic device over a 10-week intervention period and their progress was evaluated serially with the Fugl-Meyer and Modified Ashworth scales. Repeated measure analyses were used to assess group differences in locations of peak activity in the sensorimotor cortex (SM) and the relationship of such changes with scores on the Fugl-Meyer Upper Extremity (FM UE) scale.


Patients moving their stroke-affected hand had proportionally more peak activations in the primary motor area and fewer peak activations in the somatosensory cortex than the healthy controls (P=0.009). They also showed an anterior shift of peak activity on average of 5.3-mm (P<0.001). The shift correlated negatively with FM UE scores (P=0.002).


A stroke rehabilitation grip task with a robotic device was confirmed to be feasible during fMRI scanning and thus amenable to be used to assess plastic changes in neurological motor activity. Location of peak activity in the SM is a promising clinical neuroimaging index for the evaluation and monitoring of chronic stroke patients.



Fig. (2). Spatial distributions of peak brain activation during a grip task with both hands. Dots (red, left hemisphere stroke patients; green, healthy control subjects) are overlaid on an International Consortium for Brain Mapping brain surface template (ICBM-152).

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[Abstract] Effectiveness of virtual reality-based rehabilitation versus conventional therapy on upper limb motor function of chronic stroke patients: a systematic review and meta-analysis of randomized controlled trials


Objective: To systematically review the available randomized controlled trials in the literature concerning the application of virtual reality (VR) rehabilitation interventions compared to conventional physical therapy, in regaining the upper limb motor function among patients with chronic stroke. 

Methods: A systematic electronic database search was conducted for related studies published from inauguration and until June 25, 2020 in nine databases. Another new search was done on February 1, 2021 and no new studies were identified. 

Results: Six studies were included in the analysis. Significant improvement was seen following the VR therapy in patients with chronic stroke, compared to their scores prior to it (SMD = 0.28; 95% CI = 0.03–0.53; p = .03). There was neither heterogeneity (I2 = 0% and P = .5) nor a risk of bias (P = .8) among the included studies. VR interventions produced a comparable effectiveness to that of the conventional rehabilitation, with no statistically significant difference (SMD = 0.15; 95% CI = −0.14–0.44; P = .3). There was neither heterogeneity (I2 = 40% and P = .1) nor a risk of bias (P = .5) among the included studies. 

Conclusions: The upper limb motor function of patients with chronic stroke who underwent VR-based rehabilitative intervention showed significant improvement as compared to the pre-treatment state. Our analysis also revealed no superiority of VR interventions over conservative therapies; however, the difference observed did not accomplish statistical significance.


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[ARTICLE] Design and evaluation of a novel upper limb rehabilitation robot with space training based on an end effector – Full Text


The target of this paper is to design a lightweight upper limb rehabilitation robot with space training based on end-effector configuration and to evaluate the performance of the proposed mechanism. In order to implement this purpose, an equivalent mechanism to the human being upper limb is proposed before the design. Then, a 4 degrees of freedom (DOF) end-effector-based upper limb rehabilitation robot configuration is designed to help stroke patients perform space rehabilitation training of the shoulder flexion/extension and adduction/abduction and elbow flexion/extension. Thereafter, its kinematical model is established together with the proposed equivalent upper limb mechanism. The Monte Carlo method is employed to establish their workspace. The results show that the overlap of the workspace between the proposed mechanism and the equivalent mechanism is 96.61 %. In addition, this paper also constructs a human–machine closed-chain mechanism to analyze the flexibility of the mechanism. According to the relative manipulability and manipulability ellipsoid, the highly flexible area of the mechanism accounts for 67.6 %, and the mechanism is far away from the singularity on the drinking trajectory. In the end, the single-joint training experiments and a drinking water training trajectory planning experiment are developed and the prototype is manufactured to verify it.

1 Introduction

Strokes affect thousands of people around the world, and nearly half of stroke survivors suffer from upper limb defects, which makes it difficult for them to perform activities of daily living (ADL) independently. For most patients, exercise therapy has the potential to partially restore the loss of motor function (Béjot et al., 2016). Studies indicated that long-term intensive training and practice would be beneficial to the rehabilitation process of patients (Bertani et al., 2017). Robot-assisted therapy equipment can provide high-intensity, repetitive, interactive treatments for the affected upper limbs and obtain physiological data of patients, which has been increasingly used in rehabilitation training (Manna and Dubey, 2017).

The human upper limbs have a complex physiological structure. With the cooperation of multiple bones and muscles, the upper limbs are very flexible, which puts forward many requirements for the structural design of the rehabilitation robot (Pons, 2008). At present, there are mainly two types of upper limb rehabilitation robots, i.e., an end-effector-based type and an exoskeleton type. The end-effector-based-type upper limb rehabilitation robots support and pull the end of the patients through a closed-loop linkage mechanism or a series mechanism, so as to realize the rehabilitation training of the upper limb. The most representative of the robots with the closed-loop linkage mechanisms include MIT-MANUS (Hogan et al., 1992), D-SEMUL (Kikuchi et al., 2018), CASIA-ARM (Luo et al., 2019), and SepaRRo (Chang et al., 2018). They could perform plane compound training for the human shoulder and elbow joints, mainly the adduction/abduction of the shoulder and the flexion/extension of the elbow. The working mode of the robots with the series mechanism is to drive the human upper limbs through the mechanical arms, such as MIME (Lum et al., 2002) and GENTLE/s (Loureiro et al., 2003). Compared to the robots with the closed-chain linkage mechanisms, this type of robot increases the function of assisting the human shoulder joints in performing flexion and extension training, so it can drive the human upper limbs to move in three-dimensional space.

A characteristic of the end-effector-based-type upper limb rehabilitation robots is that it does need to be aligned with the physiological axes of the human joints during training, but it also means that it cannot implement accurate single-joint rehabilitation training for patients. Moreover, the structures of the end-traction robots are relatively simple, most of which are desktop type, that cause the robot’s range of motion (ROM) to be limited, especially the insufficient flexion and extension training of the human shoulder.

The exoskeleton-type upper limb rehabilitation robot has a kinematic structure similar to that of the human upper limb, and it generates driving force on each joint of the patient’s upper limb to drive limb rehabilitation training, such as CADEN-7 (Perry et al., 2007), Harmony (Kim and Deshpande, 2017), ARMin III (Nef et al., 2009), Co-EXos (Zhang et al., 2019), Armeo Power (Jarrase et al., 2015), and LIMPACTA (Otten et al., 2015). Compared with the end-effector-based robot, the exoskeleton robot can drive the patient’s limbs to perform three-dimensional rehabilitation training, especially the large-ROM flexion/extension training of the human shoulder. In addition, the driving force of the exoskeleton directly acts on the patient’s single joint, which can perform accurate single-joint training on the upper limbs. However, this feature also causes the exoskeleton to require more joints and motors, making the exoskeleton bulky and costly. Since the joint axes of the human upper limb is constantly changing during the rehabilitation exercise, the misalignment of the mechanical axes of the exoskeleton and the biological axes of the upper limb will lead to the mismatching of the movement of the exoskeleton with the upper limb, thus causing discomfort for the patients.

In this paper, a novel 4 DOF end-effector-based upper limb rehabilitation robot with space training is proposed by combining the end-effector-based-type and exoskeleton-type robot. The robot can assist the human upper limb in performing rehabilitation training of the shoulder flexion/extension and adduction/abduction and elbow flexion/extension. Different from the desktop-type end-effector-based robot, the proposed robot can provide a wide range of shoulder flexion/extension training for the human upper limb and cover the ROM of the upper limb. Through the mutual restriction of three mutually perpendicular active joints, the robot can perform single-joint and unidirectional rehabilitation training on the human upper limb.

The rest of this paper is structured as follows. In Sect. 2, we introduce the configuration design and mechanical design of a 4 DOF end-effector-based upper limb rehabilitation robot. In Sects. 3 and 4, the kinematical performance of the proposed configuration is analyzed in a global and local area. In Sect. 5, a 4 DOF end-effector-based robot is developed for upper limb rehabilitation, and the pursuit movement experiment and the multi-joint exercise test of the prototype are done to verify the dexterity of the design.
Figure 1The configuration of robot and the human–machine closed-chain mechanism.


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[Abstract] Requirements for a home-based rehabilitation device for hand and wrist therapy after stroke


Recovering hand function to perform activities of
daily living (ADL), is a significant step for stroke survivors
experiencing paresis in their upper limb. A home-based, robot
mediated training approach for the hand allows the patient to
continue their training independently after discharge to maximise
recovery at the patient’s pace. Developing such a hand/wrist
training device that is comfortable to wear and easy to use is the
objective of this work. Using a user-centred design approach, the
first iteration of the design is based on the requirements derived
from the users and therapists, leading to a first prototype. The
prototype is then compared and evaluated against the required
features. This paper highlights the methodology used in the
process of validating the design against our initial brief.

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