井元 大介

BACKGROUND: Robot-assisted gait training (RAGT) has proven effective in addressing gait disorders in patients with stroke. However, its efficacy in patients with acute stroke has not yet been demonstrated. This pilot study is designed to evaluate the following: (1) feasibility of conducting a randomized controlled trial on RAGT for enhancing gait postacute stroke and (2) to obtain preliminary estimates regarding the potential efficacy of RAGT for achieving gait independence during the acute phase. METHODS: We will conduct an assessor-blinded, single-center, randomized controlled pilot trial involving 32 patients with acute stroke who are unable to walk. Participants will be randomly assigned to either the RAGT or the conventional gait training (CGT) groups. Each participant will receive 180 min of daily rehabilitation, including 60 min dedicated to gait training. The RAGT group will receive 40 min of RAGT and 20 min of CGT, while the CGT group will engage in 60 min of CGT. Interventions will continue for up to 8 weeks, or until participants achieve gait independence, as indicated by a Functional Ambulation Category score of ≥ 3. Feasibility outcomes will include recruitment, enrollment, protocol adherence, and retention rates. The primary clinical outcome will be the incidence of achieving gait independence during the intervention period. Secondary clinical outcomes will include gait performance measures, assessments of physical function and activity, and intervention dose. Adverse events associated with RAGT and CGT will also be documented to evaluate the safety of both interventions. DISCUSSION: Implementing RAGT during the acute phase of stroke may facilitate earlier attainment of gait independence compared to CGT. We aim to provide valuable insights into the feasibility of the proposed study design and generate preliminary data on the potential effects of RAGT on gait independence in the acute phase of stroke, providing a framework for future larger-scale trials. TRIAL REGISTRATION: This clinical trial was registered with the Japan Clinical Trials Registry (jRCT) on 19 June 2023 (registration number: jRCTs042230040). The study protocol was initially registered as version 1.0 and has since undergone minor amendments-currently on version 4.0. This protocol was written based on the latest version (ver. 4.0) registered with jRCT.

OBJECTIVE: To define long-term changes in subjective symptoms among polio survivors in Japan. DESIGN: Prospective cohort study. PATIENTS: Sixty-five polio survivors. METHODS: Surveys were conducted on subjective symptoms including muscle weakness and limb atrophy during 2007 and 2021. The results of manual muscle tests of the upper and lower limbs on both sides during 2007 were summed and scored, and the side with lower scores was defined as the poor side. The participants were classified as younger or older groups based on the median age at the first survey (i.e., 58 years old) and the subjective symptoms were compared between the two groups. RESULTS: As a whole, muscle atrophy and weakness progressed in the lower and upper limbs while fatigue was reduced. Muscle weakness progressed especially in the lower limbs on the poor side in the younger group, and in the older group it progressed in the lower limbs on the good side and the upper limbs on the poor side. CONCLUSION: The timing of progressive muscle weakness differed between the upper and lower limbs of younger and older polio survivors.

BACKGROUND: Robot-assisted gait training (RAGT) is an effective method for treating gait disorders in individuals with stroke. However, no previous studies have demonstrated the effectiveness of RAGT in individuals with acute stroke. This study aimed to investigate the effects of RAGT initiation within 1 week after onset on degree of gait independence in individuals with hemiparetic stroke. METHODS: This retrospective cohort study used propensity-score matching. Individuals admitted to Fujita Health University Hospital after stroke onset and underwent RAGT between March 2017 and June 2023 were enrolled. Ninety-two individuals were eligible and grouped into the acute (≤ 7 days after the onset) and subacute groups (8-90 days after onset). RAGT was conducted using Welwalk, primarily comprising a knee-ankle-foot orthosis type robot worn on one paralyzed lower extremity, with training sessions lasting approximately 40 min/day, occurring 3-7 days/week. The primary outcome was the gait under supervision within 90 days of onset, which was compared between groups using the log-rank test. RESULTS: After propensity-score matching, 36 individuals were included in the analysis, including 18 each in the acute and subacute groups; the participant demographics were not significantly different between the groups. RAGT was initiated at a median of 6 and 25 days after onset in the acute and subacute groups, respectively. The Kaplan-Meier curves after the log-rank test showed a significantly higher percentage and shorter median days to achieve gait under supervision in the acute group than in the subacute group. The cumulative incidence of gait under supervision events at 90 days after onset was 82.2% and 55.6% in the acute and the subacute groups, respectively. Half of the individuals achieved gait under supervision within 49 days and 75 days in the acute and subacute groups, respectively (p = 0.038). No significant differences were observed in the dose of rehabilitation program and gait training per day from onset to achieving gait under supervision. CONCLUSION: Initiation of RAGT within 1 week after stroke onset in individuals with hemiparesis may reduce the number of days required to achieve gait under supervision and increase the percentage of gait under supervision.

INTRODUCTION: Gait robots have the potential to analyze gait characteristics during gait training using mounted sensors in addition to robotic assistance of the individual's movements. However, no systems have been proposed to analyze gait performance during robot-assisted gait training. Our newly developed gait robot," Welwalk WW-2000 (WW-2000)" is equipped with a gait analysis system to analyze abnormal gait patterns during robot-assisted gait training. We previously investigated the validity of the index values for the nine abnormal gait patterns. Here, we proposed new index values for four abnormal gait patterns, which are anterior trunk tilt, excessive trunk shifts over the affected side, excessive knee joint flexion, and swing difficulty; we investigated the criterion validity of the WW-2000 gait analysis system in healthy adults for these new index values. METHODS: Twelve healthy participants simulated four abnormal gait patterns manifested in individuals with hemiparetic stroke while wearing the robot. Each participant was instructed to perform 16 gait trials, with four grades of severity for each of the four abnormal gait patterns. Twenty strides were recorded for each gait trial using a gait analysis system in the WW-2000 and video cameras. Abnormal gait patterns were assessed using the two parameters: the index values calculated for each stride from the WW-2000 gait analysis system, and assessor's severity scores for each stride. The correlation of the index values between the two methods was evaluated using the Spearman rank correlation coefficient for each gait pattern in each participant. RESULTS: The median (minimum to maximum) values of Spearman rank correlation coefficient among the 12 participants between the index value calculated using the WW-2000 gait analysis system and the assessor's severity scores for anterior trunk tilt, excessive trunk shifts over the affected side, excessive knee joint flexion, and swing difficulty were 0.892 (0.749-0.969), 0.859 (0.439-0.923), 0.920 (0.738-0.969), and 0.681 (0.391-0.889), respectively. DISCUSSION: The WW-2000 gait analysis system captured four new abnormal gait patterns observed in individuals with hemiparetic stroke with high validity, in addition to nine previously validated abnormal gait patterns. Assessing abnormal gait patterns is important as improving them contributes to stroke rehabilitation. CLINICAL TRIAL REGISTRATION: https://jrct.niph.go.jp, identifier jRCT 042190109.

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.

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).

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].

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.

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.

[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.

[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.

[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.

[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.