Limb alignment and kinematics inside a Lokomat robotic orthosis

Efficacy of Robot-Assisted Gait Therapy Compared to Conventional Therapy or Treadmill Training in Children with Cerebral Palsy: A Systematic Review with Meta-Analysis

BACKGROUND

Motor, gait and balance disorders reduce functional capabilities for activities of daily living in children with cerebral palsy (CP). Robot-assisted gait therapy (RAGT) is being used to complement conventional therapy (CT) or treadmill therapy (TT) in CP rehabilitation. The aim of this systematic review is to assess the effect of RAGT on gait, balance and functional independence in CP children, in comparison to CT or TT.

METHODS

We have conducted a systematic review with meta-analysis. A search in PubMed Medline, Web of Science, Scopus, CINAHL, PEDro and SciELO has been conducted for articles published until October 2022. Controlled clinical trials (CCT), in which RAGT was compared to TT or CT and assessed gait speed, step and stride length, width step, walking distance, cadence, standing ability, walking, running and jumping ability, gross motor function and functional independence in children with CP, have been included. Methodological quality was assessed with the PEDro scale and the pooled effect was calculated with Cohen's Standardized Mean Difference (SMD) and its 95% Confidence Interval (95% CI).

RESULTS

A total of 15 CCTs have been included, providing data from 413 participants, with an averaged methodological quality of 5.73 ± 1.1 points in PEDro. The main findings of this review are that RAGT shows better results than CT in the post-intervention assessment for gait speed (SMD 0.56; 95% CI 0.03 to 1.1), walking distance (SMD 2; 95% CI 0.36 to 3.65) and walking, running and jumping ability (SMD 0.63; 95% CI 0.12 to 1.14).

CONCLUSIONS

This study shows that the effect of RAGT is superior to CT on gait speed, walking distance and walking, running and jumping ability in post-intervention, although no differences were found between RAGT and TT or CT for the remaining variables.

The Middleware for an Exoskeleton Assisting Upper Limb Movement

This article presents the possibilities of newly developed middleware dedicated for distributed and modular control systems. The software enables the exchange of information locally, within one control module, and globally, between many modules. The executed information exchange system speed tests confirmed the correct operation of the software. The middleware was used in the control system of the active upper-limb exoskeleton. The upper-limb rehabilitation exoskeleton structure with six degrees of mechanical freedom is presented. The tests were performed using the prototype with three joints. The drives’ models of individual joints were developed and simulated. As a result, the courses of the motion trajectory were shown for different kinds of pressure on the force sensors, and different methods of signal filtering. The tests confirmed a correct operation of middleware and drives control system.

Service Robots in Catering Applications: A Review and Future Challenges

“Hello, I’m the TERMINATOR, and I’ll be your server today”. Diners might soon be feeling this greeting, with Optimus Prime in the kitchen and Wall-E then sending your order to C-3PO. In our daily lives, a version of that future is already showing up. Robotics companies are designing robots to handle tasks, including serving, interacting, collaborating, and helping. These service robots are intended to coexist with humans and engage in relationships that lead them to a better quality of life in our society. Their constant evolution and the arising of new challenges lead to an update of the existing systems. This update provides a generic vision of two questions: the advance of service robots, and more importantly, how these robots are applied in society (professional and personal) based on the market application. In this update, a new category is proposed: catering robotics. This proposal is based on the technological advances that generate new multidisciplinary application fields and challenges. Waiter robots is an example of the catering robotics. These robotic platforms might have social capacities to interact with the consumer and other robots, and at the same time, might have physical skills to perform complex tasks in professional environments such as restaurants. This paper explains the guidelines to develop a waiter robot, considering aspects such as architecture, interaction, planning, and execution.

Increased gait variability during robot-assisted walking is accompanied by increased sensorimotor brain activity in healthy people

BACKGROUND

Gait disorders are major symptoms of neurological diseases affecting the quality of life. Interventions that restore walking and allow patients to maintain safe and independent mobility are essential. Robot-assisted gait training (RAGT) proved to be a promising treatment for restoring and improving the ability to walk. Due to heterogenuous study designs and fragmentary knowlegde about the neural correlates associated with RAGT and the relation to motor recovery, guidelines for an individually optimized therapy can hardly be derived. To optimize robotic rehabilitation, it is crucial to understand how robotic assistance affect locomotor control and its underlying brain activity. Thus, this study aimed to investigate the effects of robotic assistance (RA) during treadmill walking (TW) on cortical activity and the relationship between RA-related changes of cortical activity and biomechanical gait characteristics.

METHODS

Twelve healthy, right-handed volunteers (9 females; M = 25 ± 4 years) performed unassisted walking (UAW) and robot-assisted walking (RAW) trials on a treadmill, at 2.8 km/h, in a randomized, within-subject design. Ground reaction forces (GRFs) provided information regarding the individual gait patterns, while brain activity was examined by measuring cerebral hemodynamic changes in brain regions associated with the cortical locomotor network, including the sensorimotor cortex (SMC), premotor cortex (PMC) and supplementary motor area (SMA), using functional near-infrared spectroscopy (fNIRS).

RESULTS

A statistically significant increase in brain activity was observed in the SMC compared with the PMC and SMA (p < 0.05), and a classical double bump in the vertical GRF was observed during both UAW and RAW throughout the stance phase. However, intraindividual gait variability increased significantly with RA and was correlated with increased brain activity in the SMC (p = 0.05; r = 0.57).

CONCLUSIONS

On the one hand, robotic guidance could generate sensory feedback that promotes active participation, leading to increased gait variability and somatosensory brain activity. On the other hand, changes in brain activity and biomechanical gait characteristics may also be due to the sensory feedback of the robot, which disrupts the cortical network of automated walking in healthy individuals. More comprehensive neurophysiological studies both in laboratory and in clinical settings are necessary to investigate the entire brain network associated with RAW.

Comparison of the effectiveness of partial body weight-supported treadmill exercises, robotic-assisted treadmill exercises, and anti-gravity treadmill exercises in spastic cerebral palsy

Objectives

This study aims to compare the effectiveness of the partial body weight-supported treadmill exercise (PBWSTE), robotic-assisted treadmill exercise (RATE), and anti-gravity treadmill exercise (ATE) in children with spastic cerebral palsy (CP).

Patients and methods

Between December 01, 2015 and May 01, 2016, a total of 29 children (18 males, 11 females; mean age 9.3±2.3 years; range, 6 to 14 years) with spastic CP were included in the study. The patients were randomly divided into three groups as the PBWSTE group (n=10), RATE group (n=10), and ATE group (n=9). Each group underwent a total of 20 treadmill exercise sessions for 45 min for five days a week for a total of four weeks. The patients were assessed using three-dimensional gait analysis, open-circle indirect calorimeter, six-minute walking test, and Gross Motor Functional Measurement (GMFM) scale before and after treatment and at two months of follow-up.

Results

No significant change compared to baseline was found in the walking speed on gait analysis among the groups after the treatment. There was no statistically significant difference among the groups in terms of the GFMF-D, GMFM-E and six-minute walking test (p>0.05). There was a significant improvement in the oxygen consumption in the ATE group (p>0.05) and RATE group (p>0.05), but not in the PBWSTE group (p<0.05).

Conclusion

Our study findings indicate that all three treadmill exercises have a positive impact on walking, and RATE and ATE can be used more actively in patients with spastic CP.

A review in gait rehabilitation devices and applied control techniques

PURPOSE

The aim of this review is to analyse the different existing technologies for gait rehabilitation, focusing mainly in robotic devices. Those robots help the patient to recover a lost function due to neurological gait disorders, accidents or after injury. Besides, they facilitate the identification of normal and abnormal features by registering muscle activity providing the doctor important data where he can observe the evolution of the patient.

METHOD

A deep literature review was realized using selected keywords considering not only the most common medical and engineering databases, but also other available sources that provide information on commercial and scientific gait rehabilitation devices. The founded literature for this review corresponds to control techniques for gait rehabilitation robots, since the early seventies to the present year.

RESULTS

Different control strategies for gait analysis in rehabilitation devices have been developed and implemented such as position control, force and impedance control, haptic simulation, and control of EMG signals. These control techniques are used to analyze the force of the patient during therapy, compensating it with the force generated by the mechanism in the rehabilitation device. It is observed that the largest number of studies reported, focuses on the impedance control technique. Leading to include new control techniques and validate them using the necessary protocols with ill patients, obtaining reliable results that allows a progressive and active rehabilitation.

CONCLUSIONS

With this exhaustive review, we can conclude that the degree of complexity of the rehabilitation device influences in short and long-term therapeutic results since the movements become more controlled. However, there is still a lot of work in the sense of motion control in order to perform trajectories that are more alike the natural movements of humans. There are many control techniques in other areas, which seek to improve the performance of the process. These techniques may possibly be applicable in gait rehabilitation devices, obtaining controllers that are more efficient and that adapts to different people and the necessities that entail every disease. Implications for Rehabilitation Rehabilitation helps people to improve the activities of their daily life, allowing them to observe their progress in the functional abilities as the months pass by with intensive and repetitive therapies. There is a mobility issue when the patient needs to move to the hospital or to the laboratory, which is not always feasible. For overcoming it, patients use the equipment at home to perform their daily therapy. However, they need the sufficient knowledge about its operation, also about the therapeutic movements, the therapy duration and the movement speed. Besides, is necessary to place the equipment in a proper and lively environment that helps to forget or reduce pain while the patient moves his joints progressively. The purpose of robotic rehabilitation devices is to generate repetitive and progressive movements, according to the motor disability. There are training trajectories to follow, which motivate patients to generate active movements. The benefits of robotic rehabilitation depend on the ability of each patient to adapt to the speed and load variations generated by the device, improving and reinforcing motor functions in therapy, especially in patients with advanced disabilities in early rehabilitation. Multi-joint rehabilitation devices are more effective than single-joint rehabilitation devices because they involve a higher number of muscles in the therapy. The greater the number of degrees of freedom (DoF) of the device, it cushions its effect in the patient because the inertia is reduced and higher torques are generated. The assistive technological devices allows to explore different rehabilitation techniques that motivate the patient in therapy, increasing appropriately the energy and pressure in the blood which is reflected in gradually recovering his ability to walk.

Development of VariLeg, an exoskeleton with variable stiffness actuation: first results and user evaluation from the CYBATHLON 2016

BACKGROUND

Powered exoskeletons are a promising approach to restore the ability to walk after spinal cord injury (SCI). However, current exoskeletons remain limited in their walking speed and ability to support tasks of daily living, such as stair climbing or overcoming ramps. Moreover, training progress for such advanced mobility tasks is rarely reported in literature. The work presented here aims to demonstrate the basic functionality of the VariLeg exoskeleton and its ability to enable people with motor complete SCI to perform mobility tasks of daily life.

METHODS

VariLeg is a novel powered lower limb exoskeleton that enables adjustments to the compliance in the leg, with the objective of improving the robustness of walking on uneven terrain. This is achieved by an actuation system with variable mechanical stiffness in the knee joint, which was validated through test bench experiments. The feasibility and usability of the exoskeleton was tested with two paraplegic users with motor complete thoracic lesions at Th4 and Th12. The users trained three times a week, in 60 min sessions over four months with the aim of participating in the CYBATHLON 2016 competition, which served as a field test for the usability of the exoskeleton. The progress on basic walking skills and on advanced mobility tasks such as incline walking and stair climbing is reported. Within this first study, the exoskeleton was used with a constant knee stiffness.

RESULTS

Test bench evaluation of the variable stiffness actuation system demonstrate that the stiffness could be rendered with an error lower than 30 Nm/rad. During training with the exoskeleton, both users acquired proficient skills in basic balancing, walking and slalom walking. In advanced mobility tasks, such as climbing ramps and stairs, only basic (needing support) to intermediate (able to perform task independently in 25% of the attempts) skill levels were achieved. After 4 months of training, one user competed at the CYBATHLON 2016 and was able to perform 3 (stand-sit-stand, slalom and tilted path) out of 6 obstacles of the track. No adverse events occurred during the training or the competition.

CONCLUSION

Demonstration of the applicability to restore ambulation for people with motor complete SCI was achieved. The CYBATHLON highlighted the importance of training and gaining experience in piloting an exoskeleton, which were just as important as the technical realization of the robot.

Decrease of spasticity after hybrid assistive limb® training for a patient with C4 quadriplegia due to chronic SCI

CONTEXT

Recently, locomotor training with robotic assistance has been found effective in treating spinal cord injury (SCI). Our case report examined locomotor training using the robotic suit hybrid assistive limb (HAL) in a patient with complete C4 quadriplegia due to chronic SCI. This is the first report examining HAL in complete C4 quadriplegia.

FINDINGS

The patient was a 19-year-old man who dislocated C3/4 during judo 4 years previously. Following the injury, he underwent C3/4 posterior spinal fusion but remained paralyzed despite rehabilitation. There was muscle atrophy under C5 level and no sensation around the anus, but partial sensation of pressure remained in the limbs. The American Spinal Injury Association impairment scale was Grade A (complete motor C4 lesion). HAL training was administered in 10 sessions (twice per week). The training sessions consisted of treadmill walking with HAL. For safety, 2 physicians and 1 therapist supported the subject for balance and weight-bearing. The device's cybernic autonomous control mode provides autonomic physical support based on predefined walking patterns. We evaluated the adverse events, walking time and distance, and the difference in muscle spasticity before and after HAL-training using a modified Ashworth scale (mAs). No adverse events were observed that required discontinuation of rehabilitation. Walking distance and time increased from 25.2 meters/7.6 minutes to 148.3 meter/15 minutes. The mAs score decreased after HAL training.

CONCLUSION

Our case report indicates that HAL training is feasible and effective for complete C4 quadriplegia in chronic SCI.

Bilateral, Misalignment-Compensating, Full-DOF Hip Exoskeleton: Design and Kinematic Validation

A shared design goal for most robotic lower limb exoskeletons is to reduce the metabolic cost of locomotion for the user. Despite this, only a limited amount of devices was able to actually reduce user metabolic consumption. Preservation of the natural motion kinematics was defined as an important requirement for a device to be metabolically beneficial. This requires the inclusion of all human degrees of freedom (DOF) in a design, as well as perfect alignment of the rotation axes. As perfect alignment is impossible, compensation for misalignment effects should be provided. A misalignment compensation mechanism for a 3-DOF system is presented in this paper. It is validated by the implementation in a bilateral hip exoskeleton, resulting in a compact and lightweight device that can be donned fast and autonomously, with a minimum of required adaptations. Extensive testing of the prototype has shown that hip range of motion of the user is maintained while wearing the device and this for all three hip DOFs. This allowed the users to maintain their natural motion patterns when they are walking with the novel hip exoskeleton.

Feasibility of Rehabilitation Training With a Newly Developed, Portable, Gait Assistive Robot for Balance Function in Hemiplegic Patients

OBJECTIVE

To investigate the clinical feasibility of a newly developed, portable, gait assistive robot (WA-H, 'walking assist for hemiplegia') for improving the balance function of patients with stroke-induced hemiplegia.

METHODS

Thirteen patients underwent 12 weeks of gait training on the treadmill while wearing WA-H for 30 minutes per day, 4 days a week. Patients' balance function was evaluated by the Berg Balance Scale (BBS), Fugl-Meyer Assessment Scale (FMAS), Timed Up and Go Test (TUGT), and Short Physical Performance Battery (SPPB) before and after 6 and 12 weeks of training.

RESULTS

There were no serious complications or clinical difficulties during gait training with WA-H. In three categories of BBS, TUGT, and the balance scale of SPPB, there was a statistically significant improvement at the 6th week and 12th week of gait training with WA-H. In the subscale of balance function of FMAS, there was statistically significant improvement only at the 12th week.

CONCLUSION

Gait training using WA-H demonstrated a beneficial effect on balance function in patients with hemiplegia without a safety issue.

Non-invasive brain stimulation and robot-assisted gait training after incomplete spinal cord injury: A randomized pilot study

BACKGROUND

Locomotor training with a robot-assisted gait orthosis (LT-RGO) and transcranial direct current stimulation (tDCS) are interventions that can significantly enhance motor performance after spinal cord injury (SCI). No studies have investigated whether combining these interventions enhances lower extremity motor function following SCI.

OBJECTIVE

Determine whether active tDCS paired with LT-RGO improves lower extremity motor function more than a sham condition, in subjects with motor incomplete SCI.

METHODS

Fifteen adults with SCI received 36 sessions of either active (n = 9) or sham (n = 6) tDCS (20 minutes) preceding LT-RGO (1 hour). Outcome measures included manual muscle testing (MMT; primary outcome measure); 6-Minute Walk Test (6MinWT); 10-Meter Walk Test (10MWT); Timed Up and Go Test (TUG); Berg Balance Scale (BBS); and Spinal Cord Independence Measure-III (SCIM-III).

RESULTS

MMT showed significant improvements after active tDCS, with the most pronounced improvement in the right lower extremity. 10MWT, 6MinWT, and BBS showed improvement for both groups. TUG and SCIM-III showed improvement only for the sham tDCS group.

CONCLUSION

Pairing tDCS with LT-RGO can improve lower extremity motor function more than LT-RGO alone. Future research with a larger sample size is recommended to determine longer-term effects on motor function and activities of daily living.

Transvertebral direct current stimulation paired with locomotor training in chronic spinal cord injury: A case study

STUDY DESIGN

This double-blind, sham-controlled, crossover case study combined transvertebral direct current stimulation (tvDCS) and locomotor training on a robot-assisted gait orthosis (LT-RGO).

OBJECTIVE

Determine whether cathodal tvDCS paired with LT-RGO leads to greater changes in function and neuroplasticity than sham tvDCS paired with LT-RGO.

SETTING

University of Kentucky (UK) HealthCare Stroke and Spinal Cord Neurorehabilitation Research at HealthSouth Cardinal Hill Hospital.

METHODS

A single subject with motor incomplete spinal cord injury (SCI) participated in 24 sessions of sham tvDCS paired with LT-RGO before crossover to 24 sessions of cathodal tvDCS paired with LT-RGO. Functional outcomes were measured with 10 Meter Walk Test (10MWT), 6 Minute Walk Test (6MWT), Spinal Cord Independence Measure-III (SCIM-III) mobility component, lower extremity manual muscle test (MMT), and Berg Balance Scale (BBS). Corticospinal changes were assessed using transcranial magnetic stimulation.

RESULTS

Improvement in 10MWT speed, SCIM-III mobility component, and BBS occurred with both conditions. 6MWT worsened after sham tvDCS and improved after cathodal tvDCS. MMT scores for both lower extremities improved following sham tvDCS but decreased following cathodal tvDCS. Corticospinal excitability increased following cathodal tvDCS but not sham tvDCS.

CONCLUSION

These results suggest that combining cathodal tvDCS and LT-RGO may improve functional outcomes, increase corticospinal excitability, and possibly decrease spasticity. Randomized controlled trials are needed to confirm these conclusions.

SPONSORSHIP

This publication was supported by the National Center for Research Resources and the National Center for Advancing Translational Sciences, National Institutes of Health, through Grant UL1TR000117, and the HealthSouth Cardinal Hill Stroke and Spinal Cord Endowment (1215375670).

LOPES II--Design and Evaluation of an Admittance Controlled Gait Training Robot With Shadow-Leg Approach

Robotic gait training is gaining ground in rehabilitation. Room for improvement lies in reducing donning and doffing time, making training more task specific and facilitating active balance control, and by allowing movement in more degrees of freedom. Our goal was to design and evaluate a robot that incorporates these improvements. LOPES II uses an end-effector approach with parallel actuation and a minimum amount of clamps. LOPES II has eight powered degrees of freedom (hip flexion/extension, hip abduction/adduction, knee flexion/extension, pelvis forward/aft and pelvis mediolateral). All other degrees of freedom can be left free and pelvis frontal- and transversal rotation can be constrained. Furthermore arm swing is unhindered. The end-effector approach eliminates the need for exact alignment, which results in a donning time of 10-14 min for first-time training and 5-8 min for recurring training. LOPES II is admittance controlled, which allows for the control over the complete spectrum from low to high impedance. When the powered degrees of freedom are set to minimal impedance, walking in the device resembles free walking, which is an important requisite to allow task-specific training. We demonstrated that LOPES II can provide sufficient support to let severely affected patients walk and that we can provide selective support to impaired aspects of gait of mildly affected patients.

Robot-assisted walking with the Lokomat: the influence of different levels of guidance force on thorax and pelvis kinematics

BACKGROUND

Little attention has been devoted to the thorax and pelvis movements during gait. The aim of this study is to compare differences in the thorax and pelvis kinematics during unassisted walking on a treadmill and during walking with robot assistance (Lokomat-system (Hocoma, Volketswil, Switzerland)).

METHODS

18 healthy persons walked on a treadmill with and without the Lokomat system at 2kmph. Three different conditions of guidance force (30%, 60% and 100%) were used during robot-assisted treadmill walking (30% body weight support). The maximal movement amplitudes of the thorax and pelvis were measured (Polhemus Liberty™ (Polhemus, Colchester, Vermont, USA) (240/16)). A repeated measurement ANOVA was conducted.

FINDINGS

Robot-assisted treadmill walking with different levels of guidance force showed significantly smaller maximal movement amplitudes for thorax and pelvis, compared to treadmill walking. Only the antero-posterior tilting of the pelvis was significantly increased during robot-assisted treadmill walking compared to treadmill walking. No significant changes of kinematic parameters were found between the different levels of guidance force.

INTERPRETATION

With regard to the thorax and pelvis movements, robot-assisted treadmill walking is significantly different compared to treadmill walking. It can be concluded that when using robot assistance, the thorax is stimulated in a different way than during walking without robot assistance, influencing the balance training during gait.

Walking with robot assistance: the influence of body weight support on the trunk and pelvis kinematics

PURPOSE

The goal was to assess in healthy participants the three-dimensional kinematics of the pelvis and the trunk during robot-assisted treadmill walking (RATW) at 0%, 30% and 50% body weight support (BWS), compared with treadmill walking (TW).

METHODS

18 healthy participants walked (2 kmph) on a treadmill with and without robot assistance (Lokomat; 60% guidance force; 0%, 30% and 50% BWS). After an acclimatisation period (four minutes), trunk and pelvis kinematics were registered in each condition (Polhemus Liberty [240 Hz]). The results were analysed using a repeated measures analysis of variance with Bonferroni correction, with the level of suspension as within-subject factor.

RESULTS

During RATW with BWS, there were significantly (1) smaller antero-posterior and lateral translations of the trunk and the pelvis; (2) smaller antero-posterior flexion and axial rotation of the trunk; (3) larger lateral flexion of the trunk; and (4) larger antero-posterior tilting of the pelvis compared with TW.

CONCLUSIONS

There are significant differences in trunk and pelvis kinematics in healthy persons during TW with and without robot assistance. These data are relevant in gait rehabilitation, relating to normal balance regulation. Additional research is recommended to further assess the influence of robot assistance on human gait.

IMPLICATIONS FOR REHABILITATION

The trunk and pelvis moves in a different way during walking with robot assistance. The data suggest that the change in movement is due to the robot device and the harness of the suspension system more than due to the level of suspension itself.

An intrinsically safe mechanism for physically coupling humans with robots

Robots are increasingly used in tasks that include physical interaction with humans. Examples can be found in the area of rehabilitation robotics, power augmentation robots, as well as assistive and orthotic devices. However, current methods of physically coupling humans with robots fail to provide intrinsic safety, adaptation and efficiency, which limit the application of wearable robotics only to laboratory and controlled environments. In this paper we present the design and verification of a novel mechanism for physically coupling humans and robots. The device is intrinsically safe, since it is based on passive, non-electric features that are not prone to malfunctions. The device is capable of transmitting forces and torques in all directions between the human user and the robot. Moreover, its re-configurable nature allows for easy and consistent adjustment of the decoupling force. The latter makes the mechanism applicable to a wide range of human-robot coupling applications, ranging from low-force rehabilitation-therapy scenarios to high-force augmentation cases.

Feasibility of rehabilitation training with a newly developed wearable robot for patients with limited mobility

OBJECTIVE

To investigate the feasibility of rehabilitation training with a new wearable robot.

DESIGN

Before-after clinical intervention.

SETTING

University hospital and private rehabilitation facilities.

PARTICIPANTS

A convenience sample of patients (N=38) with limited mobility. The underlying diseases were stroke (n=12), spinal cord injuries (n=8), musculoskeletal diseases (n=4), and other diseases (n=14).

INTERVENTIONS

The patients received 90-minute training with a wearable robot twice per week for 8 weeks (16 sessions).

MAIN OUTCOME MEASURES

Functional ambulation was assessed with the 10-m walk test (10MWT) and the Timed Up & Go (TUG) test, and balance ability was assessed with the Berg Balance Scale (BBS). Both assessments were performed at baseline and after rehabilitation.

RESULTS

Thirty-two patients completed 16 sessions of training with the wearable robot. The results of the 10MWT included significant improvements in gait speed, number of steps, and cadence. Although improvements were observed, as measured with the TUG test and BBS, the results were not statistically significant. No serious adverse events were observed during the training.

CONCLUSIONS

Eight weeks of rehabilitative training with the wearable robot (16 sessions of 90min) could be performed safely and effectively, even many years after the subjects received their diagnosis.

Brain stimulation paired with novel locomotor training with robotic gait orthosis in chronic stroke: a feasibility study

OBJECTIVES

1) To investigate the feasibility of combining transcranial direct current stimulation (tDCS) to the lower extremity (LE) motor cortex with novel locomotor training to facilitate gait in subjects with chronic stroke and low ambulatory status, and 2) to obtain insight from study subjects and their caregivers to inform future trial design.

METHODS

Double-blind, randomized controlled study with additional qualitative exploratory descriptive design. One-month follow-up.10 subjects with stroke were recruited and randomized to active tDCS or sham tDCS for 12 sessions. Both groups participated in identical locomotor training with a robotic gait orthosis (RGO) following each tDCS session. RGO training protocol was designed to harness cortical neuroplasticity. Data analysis included assessment of functional and participation outcome measures and qualitative thematic analysis.

RESULTS

Eight subjects completed the study. Both groups demonstrated trends toward improvement, but the active tDCS group showed greater improvement than the sham group. Qualitative analyses indicated beneficial effects of this combined intervention.

CONCLUSIONS

It is feasible to combine tDCS targeting the LE motor cortex with our novel locomotor training. It appears that tDCS has the potential to enhance the effectiveness of gait training in chronic stroke. Insights from participants provide additional guidance in designing future trials.

Treadmill motor current value based walk phase estimation

We have developed a gait rehabilitation robot for hemiplegic patients using the treadmill. A walk phase, which includes time balance of stance and swing legs, is one of the most basic indexes to evaluate patients' gait. In addition, the walking phase is one of the indexes to control our robotic rehabilitation system. However, conventional methods to measure the walk phase require another system such as the foot switch and force plate. In this paper, an original algorithm to estimate the walk phase of a person on a treadmill using only the current value of DC motor to control the treadmill velocity is proposed. This algorithm was verified by experiments on five healthy subjects, and the walk phase of four subjects could be estimated in 0.2 (s) errors. However, the algorithm had erroneously identified a period of time in the stance phase as swing phase time when little body weight loaded on the subject's leg. Because a period of time with little body weight to affected leg is often observed in a hemiplegic walk, the proposed algorithm might fail to properly estimate the walk phase of hemiplegic patients. However, this algorithm could be used to estimate the time when body weight is loaded on patient legs, and thus could be used as a new quantitative evaluation index.

Kinematic trajectories while walking within the Lokomat robotic gait-orthosis

Background One of the most popular robot assisted rehabilitation devices used is the Lokomat. Unfortunately, not much is known about the behaviors exhibited by subjects in this device. The goal of this study was to evaluate the kinematic patterns of individuals walking inside the Lokomat compared to those demonstrated on a treadmill. Methods Six healthy subjects walked on a treadmill and inside the Lokomat while the motions of the subject and Lokomat were tracked. Joint angles and linear motion were determined for Lokomat and treadmill walking. We also evaluated the variability of the patterns, and the repeatability of measuring techniques. Findings The overall kinematics in the Lokomat are similar to those on a treadmill, however there was significantly more hip and ankle extension, and greater hip and ankle range of motion in the Lokomat (P<0.05). Additionally, the linear movement of joints was reduced in the Lokomat. Subjects tested on repeated sessions presented consistent kinematics, demonstrating the ability to consistently setup and test subjects. Interpretation The reduced degrees of freedom in the Lokomat are believed to be the reason for the specific kinematic differences. We found that despite being firmly attached to the device there was still subject movement relative to the Lokomat. This led to variability in the patterns, where subjects altered their gait pattern from step to step. These results are clinically important as a variable step pattern has been shown to be a more effective gait training strategy than one which forces the same kinematic pattern in successive steps.

Abnormal joint torque patterns exhibited by chronic stroke subjects while walking with a prescribed physiological gait pattern

Background

It is well documented that individuals with chronic stroke often exhibit considerable gait impairments that significantly impact their quality of life. While stroke subjects often walk asymmetrically, we sought to investigate whether prescribing near normal physiological gait patterns with the use of the Lokomat robotic gait-orthosis could help ameliorate asymmetries in gait, specifically, promote similar ankle, knee, and hip joint torques in both lower extremities. We hypothesized that hemiparetic stroke subjects would demonstrate significant differences in total joint torques in both the frontal and sagittal planes compared to non-disabled subjects despite walking under normal gait kinematic trajectories.

Methods

A motion analysis system was used to track the kinematic patterns of the pelvis and legs of 10 chronic hemiparetic stroke subjects and 5 age matched controls as they walked in the Lokomat. The subject's legs were attached to the Lokomat using instrumented shank and thigh cuffs while instrumented footlifters were applied to the impaired foot of stroke subjects to aid with foot clearance during swing. With minimal body-weight support, subjects walked at 2.5 km/hr on an instrumented treadmill capable of measuring ground reaction forces. Through a custom inverse dynamics model, the ankle, knee, and hip joint torques were calculated in both the frontal and sagittal planes. A single factor ANOVA was used to investigate differences in joint torques between control, unimpaired, and impaired legs at various points in the gait cycle.

Results

While the kinematic patterns of the stroke subjects were quite similar to those of the control subjects, the kinetic patterns were very different. During stance phase, the unimpaired limb of stroke subjects produced greater hip extension and knee flexion torques than the control group. At pre-swing, stroke subjects inappropriately extended their impaired knee, while during swing they tended to abduct their impaired leg, both being typical abnormal torque synergy patterns common to stroke gait.

Conclusion

Despite the Lokomat guiding stroke subjects through physiologically symmetric kinematic gait patterns, abnormal asymmetric joint torque patterns are still generated. These differences from the control group are characteristic of the hip hike and circumduction strategy employed by stroke subjects.

The Effects on Kinematics and Muscle Activity of Walking in a Robotic Gait Trainer During Zero-Force Control

"Assist as needed" control algorithms promote activity of patients during robotic gait training. Implementing these requires a free walking mode of a device, as unassisted motions should not be hindered. The goal of this study was to assess the normality of walking in the free walking mode of the LOPES gait trainer, an 8 degrees-of-freedom lightweight impedance controlled exoskeleton. Kinematics, gait parameters and muscle activity of walking in a free walking mode in the device were compared with those of walking freely on a treadmill. Average values and variability of the spatio-temporal gait variables showed no or small (relative to cycle-to-cycle variability) changes and the kinematics showed a significant and relevant decrease in knee angle range only. Muscles involved in push off showed a small decrease, whereas muscles involved in acceleration and deceleration of the swing leg showed an increase of their activity. Timing of the activity was mainly unaffected. Most of the observed differences could be ascribed to the inertia of the exoskeleton. Overall, walking with the LOPES resembled free walking, although this required several adaptations in muscle activity. These adaptations are such that we expect that Assist as Needed training can be implemented in LOPES.