Effects of robot-assisted gait training using the Welwalk on gait independence for individuals with hemiparetic stroke: an assessor-blinded, multicenter randomized controlled trial.

BACKGROUND: Gait disorder remains a major challenge for individuals with stroke, affecting their quality of life and increasing the risk of secondary complications. Robot-assisted gait training (RAGT) has emerged as a promising approach for improving gait independence in individuals with stroke. This study aimed to evaluate the effect of RAGT in individuals with subacute hemiparetic stroke using a one-leg assisted gait robot called Welwalk WW-1000. METHODS: An assessor-blinded, multicenter randomized controlled trial was conducted in the convalescent rehabilitation wards of eight hospitals in Japan. Participants with first-ever hemiparetic stroke who could not walk at pre-intervention assessment were randomized to either the Welwalk group, which underwent RAGT with conventional physical therapy, or the control group, which underwent conventional physical therapy alone. Both groups received 80 min of physical therapy per day, 7 days per week, while the Welwalk group received 40 min of RAGT per day, 6 days per week, as part of their physical therapy. The primary outcome was gait independence, as assessed using the Functional Independence Measure Walk Score. RESULTS: A total of 91 participants were enrolled, 85 of whom completed the intervention. As a result, 91 participants, as a full analysis set, and 85, as a per-protocol set, were analyzed. The primary outcome, the cumulative incidence of gait-independent events, was not significantly different between the groups. Subgroup analysis revealed that the interaction between the intervention group and stroke type did not yield significant differences in either the full analysis or per-protocol set. However, although not statistically significant, a discernible trend toward improvement with Welwalk was observed in cases of cerebral infarction for the full analysis and per-protocol sets (HR 4.167 [95%CI 0.914-18.995], p = 0.065, HR 4.443 [95%CI 0.973-20.279], p = 0.054, respectively). CONCLUSIONS: The combination of RAGT using Welwalk and conventional physical therapy was not significantly more effective than conventional physical therapy alone in promoting gait independence in individuals with subacute hemiparetic stroke, although a trend toward earlier gait independence was observed in individuals with cerebral infarction. TRIAL REGISTRATION: This study was registered with the Japan Registry of Clinical Trials ( https://jrct.niph.go.jp ; jRCT 042180078) on March 3, 2019.

Random walk and cell morphology dynamics in Naegleria gruberi.

Amoeboid cell movement and migration are wide-spread across various cell types and species. Microscopy-based analysis of the model systems Dictyostelium and neutrophils over the years have uncovered generality in their overall cell movement pattern. Under no directional cues, the centroid movement can be quantitatively characterized by their persistence to move in a straight line and the frequency of re-orientation. Mathematically, the cells essentially behave as a persistent random walker with memory of two characteristic time-scale. Such quantitative characterization is important from a cellular-level ethology point of view as it has direct connotation to their exploratory and foraging strategies. Interestingly, outside the amoebozoa and metazoa, there are largely uncharacterized species in the excavate taxon Heterolobosea including amoeboflagellate Naegleria. While classical works have shown that these cells indeed show typical amoeboid locomotion on an attached surface, their quantitative features are so far unexplored. Here, we analyzed the cell movement of Naegleria gruberi by employing long-time phase contrast imaging that automatically tracks individual cells. We show that the cells move as a persistent random walker with two time-scales that are close to those known in Dictyostelium and neutrophils. Similarities were also found in the shape dynamics which are characterized by the appearance, splitting and annihilation of the curvature waves along the cell edge. Our analysis based on the Fourier descriptor and a neural network classifier point to importance of morphology features unique to Naegleria including complex protrusions and the transient bipolar dumbbell morphologies.

Effect of gait training using Welwalk on gait pattern in individuals with hemiparetic stroke: a cross-sectional study.

Introduction: We aimed to explore the effect of gait training using Welwalk on gait patterns by comparing differences in gait patterns between robotic-assisted gait training using Welwalk and gait training using an orthosis in individuals with hemiparetic stroke. Methods: This study included 23 individuals with hemiparetic stroke who underwent gait training with Welwalk combined with overground gait training using an orthosis. Three-dimensional motion analysis on a treadmill was performed under two conditions for each participant: during gait training with Welwalk and with the ankle-foot orthosis. The spatiotemporal parameters and gait patterns were compared between the two conditions. Results: The affected step length was significantly longer, the step width was significantly wider, and the affected single support phase ratio was significantly higher in the Welwalk condition than in the orthosis condition. The index values of abnormal gait patterns were significantly lower while using Welwalk than in the orthosis condition. The following four indices were lower in the Welwalk condition: contralateral vaulting, insufficient knee flexion, excessive hip external rotation during the paretic swing phase, and paretic forefoot contact. Discussion: Gait training using Welwalk increased the affected step length, step width, and single support phase while suppressing abnormal gait patterns as compared to gait training using the ankle-foot orthosis. This study suggests that gait training using Welwalk may promote a more efficient gait pattern reacquisition that suppresses abnormal gait patterns. Trial registration: Prospectively registered in the Japan Registry of Clinical Trials (https://jrct.niph.go.jp; jRCTs042180152).

Pre-set estimation-based in-silico silhouette-based methodology for improving the robustness to viewing direction difference for assisting forensic gait analysis.

Forensic gait analysis is used to visually and quantitatively analyze information regarding the appearance and style of walking that can be presented as evidence in the court. The demand for analyzing CCTV pedestrian footage in video surveillance has been increasing. The dependence of the accuracy of semiautomatic silhouette-based analysis, often used in forensic science, on the differences in the viewing directions is a very challenging issue that is yet to be resolved for real case applications. Currently, the different viewing directions used in comparison footage significantly decrease the accuracy of same person analysis when using the silhouette-based method, often used in the Japanese forensic science domain. A calibration-based method was previously prosed to resolve this problem, but it requires performing an elaborate measurement procedure at the camera installation site for an accurate analysis. In this study, we propose a novel in-silico silhouette-based analysis method that significantly expands the number of viewing direction pre-set settings to 900 from the 24 used in the previous method. Several software tools have been developed to ensure that all the procedures can be executed on a computer. The experimental results confirm that the accuracy of the proposed method is comparable to that of the calibration-based method. Furthermore, the practical comparison results from actual consultation confirmed the effectiveness of the proposed method under existing viewing direction differences. We therefore anticipate that the proposed method will be beneficial for improving the analysis accuracy in real cases and therefore serve as a substitute of the previous method.

A novel gait analysis system for detecting abnormal hemiparetic gait patterns during robot-assisted gait training: A criterion validity study among healthy adults.

Introduction: Robot-assisted gait training has been reported to improve gait in individuals with hemiparetic stroke. Ideally, the gait training program should be customized based on individuals' gait characteristics and longitudinal changes. However, a gait robot that uses gait characteristics to provide individually tailored gait training has not been proposed. The new gait training robot, "Welwalk WW-2000," permits modification of various parameters, such as time and load of mechanical assistance for a patient's paralyzed leg. The robot is equipped with sensors and a markerless motion capture system to detect abnormal hemiparetic gait patterns during robot-assisted gait training. Thus, it can provide individually tailored gait training. This study aimed to investigate the criterion validity of the gait analysis system in the Welwalk WW-2000 in healthy adults. Materials and methods: Twelve healthy participants simulated nine abnormal gait patterns that were often manifested in individuals with hemiparetic stroke while wearing the robot. Each participant was instructed to perform a total of 36 gait trials, with four levels of severity for each abnormal gait pattern. Fifteen strides for each gait trial were recorded using the markerless motion capture system in the Welwalk WW-2000 and a marker-based three-dimensional (3D) motion analysis system. The abnormal gait pattern index was then calculated for each stride from both systems. The correlation of the index values between the two methods was evaluated using Spearman's rank correlation coefficients for each gait pattern in each participant. Results: Using the participants' index values for each abnormal gait pattern obtained using the two motion analysis methods, the median Spearman's rank correlation coefficients ranged from 0.68 to 0.93, which corresponded to moderate to very high correlation. Conclusion: The gait analysis system in the Welwalk WW-2000 for real-time detection of abnormal gait patterns during robot-assisted gait training was suggested to be a valid method for assessing gait characteristics in individuals with hemiparetic stroke. Clinical trial registration: [https://jrct.niph.go.jp], identifier [jRCT 042190109].

Comparative mapping of crawling-cell morphodynamics in deep learning-based feature space.

Navigation of fast migrating cells such as amoeba Dictyostelium and immune cells are tightly associated with their morphologies that range from steady polarized forms that support high directionality to those more complex and variable when making frequent turns. Model simulations are essential for quantitative understanding of these features and their origins, however systematic comparisons with real data are underdeveloped. Here, by employing deep-learning-based feature extraction combined with phase-field modeling framework, we show that a low dimensional feature space for 2D migrating cell morphologies obtained from the shape stereotype of keratocytes, Dictyostelium and neutrophils can be fully mapped by an interlinked signaling network of cell-polarization and protrusion dynamics. Our analysis links the data-driven shape analysis to the underlying causalities by identifying key parameters critical for migratory morphologies both normal and aberrant under genetic and pharmacological perturbations. The results underscore the importance of deciphering self-organizing states and their interplay when characterizing morphological phenotypes.

Usefulness of Electromyography to Predict Future Muscle Weakness in Clinically Unaffected Muscles of Polio Survivors.

BACKGROUND: Post-polio syndrome-induced muscle weakness may develop in limbs that have had normal muscle strength and have been considered unaffected by polio. OBJECTIVE: To investigate the utility of electromyography (EMG) for predicting future muscle weakness in clinically unaffected limb muscles of polio survivors. DESIGN: Retrospective study. SETTING: Academic polio clinic. PARTICIPANTS: Polio survivors (N = 77) who underwent EMG between April 2008 and March 2010 and were followed for at least 2 years. MATERIALS AND METHODS: Chart reviews were conducted to extract baseline EMG and manual muscle strength test (MMT) results to investigate the relationship between baseline EMG abnormalities and change in muscle strength over 2 years for various upper and lower limb muscles that control movement in the limb joints. MAIN OUTCOME MEASUREMENTS: Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of EMG findings for prediction of subsequent muscle weakness. RESULTS: EMG data were available for 44 deltoid, 59 biceps brachii, 60 triceps brachii, 59 vastus lateralis, 59 tibialis anterior, and 55 gastrocnemius (medial head) muscles. The percentage of muscles with an initial MMT of grade 5 that developed weakness over 2 years of follow-up was approximately 15% for most muscle types. Sensitivity of EMG to predict subsequent weakness was higher in the lower limbs (0.67-1.00). Specificity was higher in the biceps brachii (0.83). PPV was higher in the biceps brachii (0.50). NPV was higher in the lower limbs (0.89-1.00) but lower in the deltoid (0.75). CONCLUSION: EMG abnormalities were detected in some clinically normal muscles of polio survivors. EMG abnormalities predicted muscle weakness 2 years later, although the strength of this relationship varied depending on the muscle.

Factors associated with falls in Japanese polio survivors.

Purpose: To identify factors associated with falls in Japanese polio survivors and assess the extent of their impact.Materials and methods: Subjects were 128 polio survivors. Fall history and fear of falling, lower limb muscle strength, gait ability (determined by walking speed and number of steps per day), post-polio syndrome incidence, and orthosis or walking aid use were assessed, and factors associated with falls were identified using logistic regression analysis.Results: The fall rate was 64%. Fallers (subjects with one or more falls in the preceding 12 months) had low lower limb muscle strength, slow walking speed, high total scores on the Fall Efficacy Scale-International, which assesses fear of falling, and a high orthosis use rate. Knee extension muscle strength on the weaker side was identified as a main factor influencing risk of falls (odds ratio: 0.72, 95% confidence interval: 0.56-0.96). Receiver operating characteristic curve analysis gave a cutoff value for knee extension muscle strength on the weaker side of 0.42 N/kg or lower.Conclusion: Low knee extension muscle strength on the weaker side was associated with falls, but predictive ability using a single internal factor might be poor. It appears that a comprehensive examination, including other factors, is required.Implications for rehabilitationAs polio survivors age, their risk of falling increases.To identify polio survivors who are at risk of falls, it is important to determine the factors associated with falls and their influence on fall risk.The results of this study showed that reduced knee extension muscle strength on the weaker side was a risk factor for falls in polio survivors.To precisely predict the risk of falls in polio survivors, a comprehensive evaluation of both internal and external factors is required.

Motion analysis of operating a balance exercise assist robot system during forward and backward movements.

[Purpose] Stand-and-ride personal mobility devices controlled by movements of the user's center of gravity are used for balance training. We aimed to describe the physical activity required to operate this type of mobility device. [Participants and Methods] Eleven healthy males performed the following tasks: 1) moving their center of gravity forward or backward while standing on the floor (control task) and, 2) moving the mobility device forward or backward by moving their center of gravity (experimental task). [Results] We observed that the displacement of the center of gravity and the center of pressure, as well as angular displacements of the hips and knee joints, and maximum muscle activities of the biceps femoris, the medial head of the gastrocnemius and peroneus longus muscles were lesser during the experimental than during the control task. The distance moved by the device was significantly greater than the displacement of the user's center of gravity during the experimental task. [Conclusion] We observed that moving the device forward or backward required lesser physical activity than that required to shift the user's center of gravity forward or backward while standing on the floor. Additionally, we observed that even a small displacement of the user's center of gravity produced a large displacement of the device. We concluded that during balance training, the greater and more easily perceived movement of the mobility device would provide helpful feedback to the user.

Kinematic, kinetic, and electromyographic characteristics during quiet standing on a balance exercise assist robot.

[Purpose] The balance exercise assist robot is a training device based on a personal transport assistance robot ridden in the standing position. The personal transport assistance robot uses an inverted pendulum control system and moves in response to movements of the user's center of gravity. The purpose of this study was to describe the characteristics of postural control during the action of stopping the personal transport assistance robot. [Participants and Methods] Eleven healthy male participants were required to maintain a standing position for 30 s; each task was performed 10 times. The measurement conditions were as follows: (1) on the floor; (2) on the robot, touching the handlebars; and (3) on the robot, not touching the handlebars. [Results] During the robotic tasks, the total locus lengths of the center of gravity and total joint momentums of the hip, knee, and ankle joints were larger, and the amount of displacement of the center of pressure was smaller than that during the floor task. Posture control on the robot was performed actively by mechanical interaction of the ankle, knee, and hip joints within a small base of support. [Conclusion] The balance exercise assist robot can be useful for postural control exercises because maintaining a standing position on the personal transport assistance robot required active postural control.

Gait training using a stationary, one-leg gait exercise assist robot for chronic stroke hemiplegia: a case report.

[Purpose] The Gait Exercise Assist Robot (GEAR) is a stationary, one-leg robot for gait training. The purpose of this case study was to evaluate the efficacy of rehabilitation using GEAR training for chronic stroke hemiplegia. [Participant and Methods] The participant was a 66-year-old male stroke survivor with left hemiparesis due to a right putaminal hemorrhage. He could walk slowly under supervision, although his gait had a constant forward trunk lean, with flexed knee, and a lack of hip extension movement on the affected side. Gait training using GEAR and physical therapy were performed for 14 days. Under both training conditions, the physical therapist made the participant conscious of extension movement of the hip joint in the affected-side stance phase. The robotic assistance was adjusted to maximize voluntary movement while observing gait. Physical function and gait ability parameters were evaluated before and after training. [Results] After training, extension motion of the hip joint increased in the affected-side stance phase, and body weight was transferred smoothly onto the affected-side limb, leading to an improvement in gait speed. [Conclusion] Gait training using GEAR and physical therapy may improve gait pattern and speed in patients with chronic stroke hemiplegia.

Changes in postural strategy during exercise against perturbation using the balance exercise assist robot: a pilot study.

[Purpose] To clarify the changes in postural strategy by evaluating leg joint motion and muscle activity before and after continuous exercise against perturbation using the Balance Exercise Assist Robot (BEAR). [Subjects and Methods] Nine healthy subjects (male 7, female 2; mean age 23 ± 1 years) performed a postural perturbation coping exercise only. In the task, the robot leaned and moved automatically. Participants were instructed to maintain their default upright position and they performed the exercise five times in a row (1 minute/trial). Changes in total movement distance, range of motion of each joint (hip, knee, ankle), and mean activity of each muscle for the first and fifth trials were compared. [Results] The total movement distance of BEAR and range of motion in the hip decreased significantly from the first trial to the last trial. No change in muscle activity was observed in the rectus femoris, biceps femoris, tibialis anterior or gastrocnemius. [Conclusion] The results for exercise against perturbation using BEAR in this study suggest that BEAR may be a promising method to improve the ankle strategy for maintaining a standing posture.

Rectified directional sensing in long-range cell migration.

How spatial and temporal information are integrated to determine the direction of cell migration remains poorly understood. Here, by precise microfluidics emulation of dynamic chemoattractant waves, we demonstrate that, in Dictyostelium, directional movement as well as activation of small guanosine triphosphatase Ras at the leading edge is suppressed when the chemoattractant concentration is decreasing over time. This 'rectification' of directional sensing occurs only at an intermediate range of wave speed and does not require phosphoinositide-3-kinase or F-actin. From modelling analysis, we show that rectification arises naturally in a single-layered incoherent feedforward circuit with zero-order ultrasensitivity. The required stimulus time-window predicts ~5 s transient for directional sensing response close to Ras activation and inhibitor diffusion typical for protein in the cytosol. We suggest that the ability of Dictyostelium cells to move only in the wavefront is closely associated with rectification of adaptive response combined with local activation and global inhibition.

Phosphorylation of chemoattractant receptors regulates chemotaxis, actin reorganization and signal relay.

Migratory cells, including mammalian leukocytes and Dictyostelium, use G-protein-coupled receptor (GPCR) signaling to regulate MAPK/ERK, PI3K, TORC2/AKT, adenylyl cyclase and actin polymerization, which collectively direct chemotaxis. Upon ligand binding, mammalian GPCRs are phosphorylated at cytoplasmic residues, uncoupling G-protein pathways, but activating other pathways. However, connections between GPCR phosphorylation and chemotaxis are unclear. In developing Dictyostelium, secreted cAMP serves as a chemoattractant, with extracellular cAMP propagated as oscillating waves to ensure directional migratory signals. cAMP oscillations derive from transient excitatory responses of adenylyl cyclase, which then rapidly adapts. We have studied chemotactic signaling in Dictyostelium that express non-phosphorylatable cAMP receptors and show through chemotaxis modeling, single-cell FRET imaging, pure and chimeric population wavelet quantification, biochemical analyses and TIRF microscopy, that receptor phosphorylation is required to regulate adenylyl cyclase adaptation, long-range oscillatory cAMP wave production and cytoskeletal actin response. Phosphorylation defects thus promote hyperactive actin polymerization at the cell periphery, misdirected pseudopodia and the loss of directional chemotaxis. Our data indicate that chemoattractant receptor phosphorylation is required to co-regulate essential pathways for migratory cell polarization and chemotaxis. Our results significantly extend the understanding of the function of GPCR phosphorylation, providing strong evidence that this evolutionarily conserved mechanism is required in a signal attenuation pathway that is necessary to maintain persistent directional movement of Dictyostelium, neutrophils and other migratory cells.