The impact of ankle-foot orthoses on toe clearance strategy in hemiparetic gait: a cross-sectional study

Effects of walking speeds on lower extremity kinematic synergy in toe vertical position control: An experimental study

BACKGROUND

This study aimed to investigate whether lower limb joints mutually compensate for each other, resulting in motor synergy that suppresses toe vertical position fluctuation, and whether walking speeds affect lower limb synergy.

METHODS

Seventeen male university students walked at slow (0.85 ± 0.04 m/s), medium (1.43 ± 0.05 m/s) and fast (1.99 ± 0.06 m/s) speeds on a 15-m walkway while lower limb kinematic data were collected. Uncontrolled manifold analysis was used to quantify the strength of synergy. Two-way (speed × phase) repeated-measures analysis of variance was used to analyze all dependent variables.

RESULTS

A significant speed-by-phase interaction was observed in the synergy index (SI) (P  < .001). At slow walking speeds, subjects had greater SI during mid-swing (P  < .001), while at fast walking speeds, they had greater SI during early-swing (P  < .001). During the entire swing phase, fast walking exhibited lower SI values than medium (P  = .005) and slow walking (P  = .027).

CONCLUSION

Kinematic synergy plays a crucial role in controlling toe vertical position during the swing phase, and fast walking exhibits less synergy than medium and slow walking. These findings contribute to a better understanding of the role of kinematic synergy in gait stability and have implications for the development of interventions aimed at improving gait stability and reducing the risk of falls.

Optimizing 3D printed ankle-foot orthoses for patients with stroke: Importance of effective elastic modulus and finite element simulation

Patients with stroke often use ankle-foot orthoses (AFOs) for gait improvement. 3D printing technology has become a popular tool in recent years for the production of AFOs due to its strengths on customization and rapid manufacturing. However, the porosity of the 3D printed materials affects the kinetic features of these orthoses, leading to its lower-strength than solid ones. The effective elastic modulus of 3D printed material was measured following standard test method to obtain the kinetic features precisely in a finite element simulation. This study demonstrated that the porosity of 3D printed samples using 100% fill density was 11% for PLA and 16% for Nylon. As a result, their effective elastic modulus was reduced to 1/3 and 1/12 of fully solid objects, respectively, leading to a lower stiffness of 3D printed orthoses. A fatigue testing platform was built to verify our finite element model, and the findings of the fatigue test were consistent with the analysis of the finite element model. Further, our AFO has been proven to have a lifespan exceeding 200 thousand steps. Our study highlights the significance of determining the actual porosity of 3D printed samples by calculating the effective elastic modulus, which leads to a more precise finite element simulation and enables reliable prediction of the kinetic features of the AFO. Overall, this study provides valuable insights into the production and optimization of 3D printed AFOs for patients with stroke.

Movement Component Analysis of Reaching Strategies in Individuals With Stroke: Preliminary Study

BACKGROUND

Upper limb motor paresis is a major symptom of stroke, which limits activities of daily living and compromises the quality of life. Kinematic analysis offers an in-depth and objective means to evaluate poststroke upper limb paresis, with anticipation for its effective application in clinical settings.

OBJECTIVE

This study aims to compare the movement strategies of patients with hemiparesis due to stroke and healthy individuals in forward reach and hand-to-mouth reach, using a simple methodology designed to quantify the contribution of various movement components to the reaching action.

METHODS

A 3D motion analysis was conducted, using a simplified marker set (placed at the mandible, the seventh cervical vertebra, acromion, lateral epicondyle of the humerus, metacarpophalangeal [MP] joint of the index finger, and greater trochanter of the femur). For the forward reach task, we measured the distance the index finger's MP joint traveled from its starting position to the forward target location on the anterior-posterior axis. For the hand-to-mouth reach task, the shortening of the vertical distance between the index finger MP joint and the position of the chin at the start of the measurement was measured. For both measurements, the contributions of relevant upper limb and trunk movements were calculated.

RESULTS

A total of 20 healthy individuals and 10 patients with stroke participated in this study. In the forward reach task, the contribution of shoulder or elbow flexion was significantly smaller in participants with stroke than in healthy participants (mean 52.5%, SD 24.5% vs mean 85.2%, SD 4.5%; P<.001), whereas the contribution of trunk flexion was significantly larger in stroke participants than in healthy participants (mean 34.0%, SD 28.5% vs mean 3.0%, SD 2.8%; P<.001). In the hand-to-mouth reach task, the contribution of shoulder or elbow flexion was significantly smaller in participants with stroke than in healthy participants (mean 71.8%, SD 23.7% vs mean 90.7%, SD 11.8%; P=.009), whereas shoulder girdle elevation and shoulder abduction were significantly larger in participants with stroke than in healthy participants (mean 10.5%, SD 5.7% vs mean 6.5%, SD 3.0%; P=.02 and mean 16.5%, SD 18.7% vs mean 3.0%, SD 10.4%; P=.02, respectively).

CONCLUSIONS

Compared with healthy participants, participants with stroke achieved a significantly greater distance via trunk flexion in the forward reach task and shoulder abduction and shoulder girdle elevation in the hand-to-mouth reach task, both of these differences are regarded as compensatory movements. Understanding the characteristics of individual motor strategies, such as dependence on compensatory movements, may contribute to tailored goal setting in stroke rehabilitation.

ToulGaitViz: a tool for the systematic description of lower limb clearance during the swing phase of hemiparetic gait after stroke. A cohort study

BACKGROUND

In post-stroke hemiparetic subjects, a systematic and quantified description of the shortening default and compensatory movements during the swing phase of gait is essential to guide treatments and assess the impact of therapeutic interventions. However, such a systematic approach does not exist in the current clinical practice.

AIM

The aim of this study was to present a method improving the quantification and visualization of the kinematics of both lower limbs during the swing phase of gait, more specifically the origin of shortening default and the weight of compensations, based on a tool specifically developed: ToulGaitViz.

DESIGN

Observational cohort study.

SETTING

Three-dimensional kinematic gait analyses of outpatients evaluated in Toulouse university hospital.

POPULATION

ToulGaitViz was applied to 151 post-stroke hemiparetic participants and 48 healthy control participants.

METHODS

ToulGaitViz is a standalone software allowing to compute 1) limb clearance as the sum of the shortening related to hip, knee and ankle flexion in the sagittal plane; 2) compensations related to the abduction of the limb and hip hiking at mid-swing. Both centimetric and angular values of the clearance were reported as well as their correlations with walking speed.

RESULTS

Overall, the contribution of compensations in clearance was higher in post-stroke hemiparetic subjects than in healthy control participants with both centimetric (130% vs. 33%; P<0.001) and angular methods (23% vs. 1.4%; P<0.001). The centimetric method better represents the specific contribution of each segment to the clearance than the angular method. Symbolically, mean kinematic data from the cohort supports the claim that 2° of pelvic obliquity is equivalent to 10° of knee flexion to increase clearance by 1 cm, emphasizing the non-proportionality between the angular values and the actual contribution to the shortening. ToulGaitViz allows visualization of clearance, segmental shortening and compensation evolution before and after any therapeutic intervention with quantitative and comprehensive data.

CONCLUSIONS

The ToulGaitViz could be systematically used in clinical practice to extract relevant kinematic data from the origin of shortening default and the weight of compensations.

CLINICAL REHABILITATION IMPACT

This tool allows better understanding of the mechanisms of action of treatments to better link them to the subjects' needs.

Effects of ankle-foot orthosis on gait pattern and spatiotemporal indices during treadmill walking in hemiparetic stroke

Ankle-foot orthosis (AFO) is known to correct abnormal gait patterns and improve walking stability and speed in patients with hemiparesis. To quantify these benefits in post-stroke gait, a three-dimensional motion analysis of gait pattern was conducted. Forty patients with hemiparesis were enrolled. A three-dimensional motion analysis system was used to analyze patients' treadmill walking with/without an AFO. Outcome measures were 12 abnormal gait indices (forefoot contact, knee extensor thrust, retropulsion of the hip, flexed-knee gait, medial whip in the stance phase, circumduction gait, hip hiking, insufficient knee flexion during the swing phase, excessive lateral shifting of the trunk, contralateral vaulting, excessive hip external rotation, and posterior pelvic tilt), calculated using kinematic data and spatiotemporal indices, and the symmetry index of double-stance and single-stance time and step length. Forefoot contact (without AFO vs. with AFO: 71.0 vs. 65.8, P < 0.001), circumduction gait (65.0 vs. 57.9, P < 0.001), and contralateral vaulting (78.2 vs. 72.2, P = 0.003) were significantly reduced, whereas excessive hip external rotation (53.7 vs. 62.8, P = 0.003) significantly increased during walking with an AFO. Hip hiking (77.1 vs. 71.7) showed marginal reduction with the use of AFO ( P = 0.096). The absolute symmetry index of double-stance time (21.9 vs. 16.1, P = 0.014) significantly decreased during walking with an AFO. AFO effectively mitigates abnormal gait patterns typical of hemiparetic gait. A 3D motion analysis system with clinically oriented indices can help assess intervention efficacy for gait abnormalities.

Effects of wearable visual cueing on gait pattern and stability in patients with Parkinson’s disease

The present study examined the effects of wearable visual cues, provided by a wearable laser device, on the gait pattern and stability in patients with Parkinson’s disease (PD). In total, 18 patients with a clinical diagnosis of idiopathic PD (Hoehn and Yahr stage II-III) and 18 healthy controls were included. The main outcome measures included spatiotemporal parameters, sagittal plane kinematic parameters of joints in lower limbs, and dynamic center of pressure (COP) parameters. Significant intra-group improvement in gait parameters was observed in PD patients. Compared with that at baseline, the gait pattern improved in PD patients under the cued condition, with longer stride length and higher toe clearance, as well as shortening of double stance phase, especially the stride length, double stance phase and toe clearance were not significantly different between cued condition and healthy control groups. In kinematics, the ankle peak dorsiflexion in swing phase and the hip range of motion (ROM) in gait cycle was significantly improved in PD patients with visual cues and close to healthy controls. Decreased anteroposterior (AP) position of COP improved gait stability in patients with PD under the cued condition. Multiple linear regression analysis showed that the AP position has a negative correlation with ankle peak dorsiflexion in swing phase. Pearson’s correlation coefficients showed that the minimum toe clearance (Mini TC) was positively correlated with the ankle peak dorsiflexion in swing phase. The immediate effect of wearable visual cues improved the gait pattern and stability in PD patients, suggesting that it may be effective when applied as an alternative technique in rehabilitation training for PD patients.

Mechanical disturbances applied by motorized ankle foot orthosis to adapt ankle muscles activation—A validation study

Background: Reduced function of ankle muscles usually leads to impaired gait. Motorized ankle foot orthoses (MAFOs) have shown potential to improve neuromuscular control and increase volitional engagement of ankle muscles. In this study, we hypothesize that specific disturbances (adaptive resistance-based perturbations to the planned trajectory) applied by a MAFO can be used to adapt the activity of ankle muscles. The first goal of this exploratory study was to test and validate two different ankle disturbances based on plantarflexion and dorsiflexion resistance while training in standing still position. The second goal was to assess neuromuscular adaptation to these approaches, namely, in terms of individual muscle activation and co-activation of antagonists.

Methods: Two ankle disturbances were tested in ten healthy subjects. For each subject, the dominant ankle followed a target trajectory while the contralateral leg was standing still: a) dorsiflexion torque during the first part of the trajectory (Stance Correlate disturbance—StC), and b) plantarflexion torque during the second part of the trajectory (Swing Correlate disturbance—SwC). Electromyography was recorded from the tibialis anterior (TAnt) and gastrocnemius medialis (GMed) during MAFO and treadmill (baseline) trials.

Results: GMed (plantarflexor muscle) activation decreased in all subjects during the application of StC, indicating that dorsiflexion torque did not enhance GMed activity. On the other hand, TAnt (dorsiflexor muscle) activation increased when SwC was applied, indicating that plantarflexion torque succeeded in enhancing TAnt activation. For each disturbance paradigm, there was no antagonist muscle co-activation accompanying agonist muscle activity changes.

Conclusion: We successfully tested novel ankle disturbance approaches that can be explored as potential resistance strategies in MAFO training. Results from SwC training warrant further investigation to promote specific motor recovery and learning of dorsiflexion in neural-impaired patients. This training can potentially be beneficial during intermediate phases of rehabilitation prior to overground exoskeleton-assisted walking. Decreased activation of GMed during StC might be attributed to the unloaded body weight in the ipsilateral side, which typically decreases activation of anti-gravity muscles. Neural adaptation to StC needs to be studied thoroughly in different postures in futures studies.

Effects of visual restoration on gait performance and kinematics of lower extremities in patients with age-related cataract

BACKGROUND

Visual inputs are critical for locomotor navigation and sensorimotor integration in the elderly; however, the mechanism needs to be explored intensively. The present study assessed the gait pattern after cataract surgery to investigate the effects of visual restoration on locomotion.

METHODS

The prospective study recruited 32 patients (70.1 ± 5.2 years) with bilateral age-related cataracts in the Department of Ophthalmology at Peking University Third Hospital from October 2016 to December 2019. The temporal-spatial gait parameters and kinematic parameters were measured by the Footscan system and inertial measurement units. Paired t -test was employed to compare data normally distributed and Wilcoxon rank-sum test for non-normally distributed.

RESULTS

After visual restoration, the walking speed increased by 9.3% (1.19 ± 0.40 m/s vs. 1.09 ± 0.34 m/s, P =0.008) and exhibited an efficient gait pattern with significant decrease in gait cycle (1.02 ± 0.08 s vs. 1.04 ± 0.07 s, P =0.012), stance time (0.66 ± 0.06 s vs. 0.68 ± 0.06 s, P =0.045), and single support time (0.36 ± 0.03 s vs. 0.37 ± 0.02 s, P =0.011). High amplitude of joint motion was detected in the sagittal plane in the left hip (37.6° ± 5.3° vs. 35.5° ± 6.2°, P =0.014), left thigh (38.0° ± 5.2° vs. 36.4° ± 5.8°, P =0.026), left shank (71.9° ± 5.7° vs. 70.1° ± 5.6°, P =0.031), and right knee (59.1° ± 4.8° vs. 56.4° ± 4.8°, P =0.001). The motor symmetry of thigh improved from 8.35 ± 5.30% to 6.30 ± 4.73% ( P =0.042).

CONCLUSIONS

The accelerated gait in response to visual restoration is characterized by decreased stance time and increased range of joint motion. Training programs for improving muscle strength of lower extremities might be helpful to facilitate the adaptation to these changes in gait.

Reaction moments matter when designing lower-extremity robots for tripping recovery

Balance recovery after tripping often requires an active adaptation of foot placement. Thus far, few attempts have been made to actively assist forward foot placement for balance recovery employing wearable devices. This study aims to explore the possibilities of active forward foot placement through two paradigms of actuation: assistive moments exerted with the reaction moments either internal or external to the human body, namely 'joint' moments and 'free' moments, respectively. Both paradigms can be applied to manipulate the motion of segments of the body (e.g., the shank or thigh), but joint actuators also exert opposing reaction moments on neighbouring body segments, altering posture and potentially inhibiting tripping recovery. We therefore hypothesised that a free moment paradigm is more effective in assisting balance recovery following tripping. The simulation software SCONE was used to simulate gait and tripping over various ground-fixed obstacles during the early swing phase. To aid forward foot placement, joint moments and free moments were applied either on the thigh to augment hip flexion or on the shank to augment knee extension. Two realizations of joint moments on the hip were simulated, with the reaction moment applied to either the pelvis or the contralateral thigh. The simulation results show that assisting hip flexion with either actuation paradigm on the thigh can result in full recovery of gait with a margin of stability and leg kinematics closely matching the unperturbed case. However, when assisting knee extension with moments on the shank, free moment effectively assist balance but joint moments with the reaction moment on the thigh do not. For joint moments assisting hip flexion, placement of the reaction moment on the contralateral thigh was more effective in achieving the desired limb dynamics than placing the reaction on the pelvis. Poor choice of placement of reaction moments may therefore have detrimental consequences for balance recovery, and removing them entirely (i.e., free moment) could be a more effective and reliable alternative. These results challenge conventional assumptions and may inform the design and development of a new generation of minimalistic wearable devices to promote balance during gait.

Effect of a rigid ankle foot orthosis and an ankle foot orthosis with an oil damper plantar flexion resistance on pelvic and thoracic movements of patients with stroke during gait

BACKGROUND

Impairments of trunk movements in gait of stroke are often reported. Ankle foot orthosis (AFO) is commonly used to improve gait of stroke; however, the effect of different types of AFOs on the pelvic and thoracic movements during gait in stroke has not been clarified.

METHODS

Thirty-four patients with stroke were randomly allocated to undergo 2 weeks of gait training by physiotherapists while wearing a rigid AFO (RAFO) with a fixed ankle or an AFO with an oil damper (AFO-OD) that provides plantarflexion resistance and free dorsiflexion. A motion capture system was used for measurements of shod gait without AFO at baseline and with and without AFO after gait training. Two-way repeated ANOVA, Wilcoxon signed-rank test, and Mann-Whitney U test were performed for the data after the gait training to know the effect of different kinds of AFOs.

RESULTS

Twenty-nine patients completed the study (AFO-OD group: 14, RAFO group: 15). Interactions were found in pelvic rotation angle, change of shank-to-vertical angle (SVA) in the stance, and paretic to non-paretic step length, which increased in AFO-OD group with AFOs (p < 0.05), while the SVA decreased in RAFO group with AFOs (p < 0.05). The main effects were found in pelvic rotation at the contralateral foot off, and thoracic tilt at foot off when an AFO was worn. The change of SVA in stance was positively correlated with the pelvic rotation in the AFO-OD group (r = 0.558). At initial contact, pelvic rotation was positively correlated with thoracic rotation in both groups.

CONCLUSIONS

The findings in 29 patients with stroke showed that pelvic and thoracic movements especially the rotation were affected by the type of AFOs. Pelvic rotation and lower limb kinematics exhibited significant improvements with AFO-OD, reflecting more desirable gait performance. On the other hand, the increase in thoracic in-phase rotation might expose the effect of insufficient trunk control and dissociation movement. Trial registration UMIN000038694, Registered 21 November 2019, https://center6.umin.ac.jp/cgi-open-bin/ctr_e/ctr_his_list.cgi?recptno=R000044048 .

Advances in the clinical application of orthotic devices for stroke and spinal cord injury since 2013

Stroke and spinal cord injury are common neurological disorders that can cause various dysfunctions. Motor dysfunction is a common dysfunction that easily leads to complications such as joint stiffness and muscle contracture and markedly impairs the daily living activities and long-term prognosis of patients. Orthotic devices can prevent or compensate for motor dysfunctions. Using orthotic devices early can help prevent and correct deformities and treat muscle and joint problems. An orthotic device is also an effective rehabilitation tool for improving motor function and compensatory abilities. In this study, we reviewed the epidemiological characteristics of stroke and spinal cord injury, provided the therapeutic effect and recent advances in the application of conventional and new types of orthotic devices used in stroke and spinal cord injury in different joints of the upper and lower limbs, identified the shortcomings with these orthotics, and suggested directions for future research.

Relationship of Recovery of Contralesional Ankle Weakness With the Corticospinal and Corticoreticular Tracts in Stroke Patients

OBJECTIVE

We investigated the relationship between contralesional ankle weakness recovery and the corticospinal tract and corticoreticular tract in stroke patients with complete injuries of the ipsilesional corticospinal tract and corticoreticular tract.

DESIGN

Thirty-six patients with complete injuries of the ipsilesional corticospinal tract and corticoreticular tract were recruited. Medical Research Council and the Functional Ambulation Category were used to determine motor function of ankle dorsiflexor and gait function. Patients were assigned into two groups: group A (poor recovery) and group B (good recovery). Fractional anisotropy, apparent diffusion coefficient, and tract volume were obtained for diffusion tensor imaging parameter.

RESULTS

A total of 58.3% of patients showed good recovery of contralesional ankle dorsiflexor weakness, with remainder having poor recovery. Tract volume of the contralesional corticoreticular tract in group B was higher than that in group A (P < 0.05); no other diffusion tensor imaging parameters were significantly different between two groups. Tract volume of the contralesional corticoreticular tract and corticospinal tract showed strong (r = 0.521) and moderate (r = 0.399) positive correlations with Medical Research Council score of contralesional ankle dorsiflexor, respectively (P < 0.05).

CONCLUSIONS

We found that the number of fibers of the contralesional corticospinal tract and corticoreticular tract was closely related to the recovery of contralesional ankle dorsiflexor weakness in stroke patients with complete injuries of the ipsilesional corticospinal tract and corticoreticular tract. Moreover, the contralesional corticoreticular tract had a closer relationship to recovery than the contralesional corticoreticular tract.

Effects of ankle-foot orthoses on the stability of post-stroke hemiparetic gait

BACKGROUND

Ankle-foot orthoses are used to improve gait stability in patients with post-stroke gait; however, there is not enough evidence to support their beneficial impact on gait stability.

AIM

To investigate the effects of ankle-foot orthoses on post-stroke gait stability.

DESIGN

An experimental study with repeated measurements of gait parameters with and without orthosis.

SETTING

Inpatients and outpatients in the Fujita Health University Hospital, Toyoake, Japan.

POPULATION

Thirty-two patients (22 males; mean age 48.3±20.0 years) with post-stroke hemiparesis participated in the study.

METHODS

Three-dimensional treadmill gait analysis was performed with and without ankle-foot orthosis for each participant. Spatiotemporal parameters, their coefficient of variation, and margin of stability were evaluated. Toe clearance, another major target of orthosis, was also examined. The effect of orthosis in the patients with severe (not able to move within the full range of motion, defying gravity) and mild ankle impairment (able to move within the full range but have problem with speed and/or smoothness of the ankle movement) was compared.

RESULTS

In the total group comparison, the decrease in the coefficient of variation of step width (P=0.012), and margin of stability on the paretic side (P=0.023) were observed. In the severe ankle impairment groups, the decreased in the coefficient of variation of the non-paretic step length (P=0.007), stride length (P=0.037), and step width (P=0.033) and margin of stability on the paretic side (P=0.006) were observed. No significant effects were observed in the mild ankle impairment group; rather, the coefficient of variation of non-paretic step length increased with the use of orthosis in this group (P=0.043); however, toe clearance increased with the use of ankle-foot orthosis (P=0.041).

CONCLUSIONS

Ankle-foot orthoses improved gait stability indices; however, the effect was either not significant or showed possible worsening in the patients with mild ankle impairment, while the effect on toe clearance was significant. These results suggest that the effects of using orthoses in patients with mild impairment should be carefully evaluated.

CLINICAL REHABILITATION IMPACT

Understanding the effects of ankle-foot orthoses on the stability of post-stroke gait and their relationship with ankle impairment severity may support clinical decision-making while prescribing orthosis for post-stroke hemiparesis.

Does Gait with an Ankle Foot Orthosis Improve or Compromise Minimum Foot Clearance?

The purpose of this study was to investigate if the use of an ankle foot orthosis in passive mode (without actuation) could modify minimum foot clearance, and if there are any compensatory mechanisms to enable these changes during treadmill gait at a constant speed. Eight participants walked on an instrumented treadmill without and with an ankle foot orthosis on the dominant limb at speeds of 0.8, 1.2, and 1.6 km/h. For each gait cycle, the minimum foot clearance and some gait linear kinematic parameters were calculated by an inertial motion capture system. Additionally, maximum hip and knee flexion and maximum ankle plantar flexion were calculated. There were no significant differences in the minimum foot clearance between gait conditions and lower limbs. However, differences were found in the swing, stance and step times between gait conditions, as well as between limbs during gait with orthosis (p < 0.05). An increase in hip flexion during gait with orthosis was observed for all speeds, and different ankle ranges of motion were observed according to speed (p < 0.05). Thus, the use of an ankle foot orthosis in passive mode does not significantly hinder minimum foot clearance, but can change gait linear and angular parameters in non-pathological individuals.

Effects of Assisted Dorsiflexion Timing on Voluntary Efforts and Compensatory Movements: A Feasibility Study in Healthy Participants

In previous research, we found that modulating the assistance timing of dorsiflexion may affect a user's voluntary efforts. This could constitute a focus area based on assistive strategies that could be developed to foster patients' voluntary efforts. In this present study, we conducted an experiment to verify the effects of ankle dorsiflexion assistance under different timings using a high-dorsiflexion assistive system. Nine healthy and young participants wore a dorsiflexion-restrictive device that enabled them to use circumduction or steppage gaits. On the basis of the transition from the stance to the swing phase of the gait, the assistance timings of the high-dorsiflexion assistive system were set to have delays, which ranged from 0 to 300 ms. The index results from eight out of nine participants evaluated compensatory movements and revealed positive strong/moderate correlations with assistance delay times (r = 0.627-0.965, p <.001), whereas the other participants also performed compensatory movement when dorsiflexion assistance timing was late. Meanwhile, the results from tibialis anterior surface electromyography from six out of nine participants showed positive strong/moderate correlations with dorsiflexion assistance delay times (r = 0.598-0.922, p <.001), indicating that tuning the assistance timing did foster these participants' voluntary dorsiflexion movements. This result indicates that there should be a trade-off between ensuring voluntary dorsiflexion movements and preventing incorrect gait patterns at different assistance timings. The findings of this feasibility study indicate the potential of developing an adaptive control method to ensure voluntary efforts during robot-assisted gait rehabilitation based on assistance timing modification. A new assistance mechanism should also be required to stimulate and motivate a patient's voluntary efforts and should reinforce the effects of active gait rehabilitation.

Pelvis-Toe Distance: 3-Dimensional Gait Characteristics of Functional Limb Shortening in Hemiparetic Stroke

We aimed to investigate whether a newly defined distance in the lower limb can capture the characteristics of hemiplegic gait compared to healthy controls. Three-dimensional gait analyses were performed on 42 patients with chronic stroke and 10 age-matched controls. Pelvis-toe distance (PTD) was calculated as the absolute distance between an anterior superior iliac spine marker and a toe marker during gait normalized by PTD in the bipedal stance. The shortening peak during the swing phase was then quantified as PTDmin. The sagittal clearance angle, the frontal compensatory angle, gait speed, and the observational gait scale were also collected. PTDmin in the stroke group showed less shortening on the affected side and excessive shortening on the non-affected side compared to controls. PTDmin on the affected side correlated negatively with the sagittal clearance peak angle and positively with the frontal compensatory peak angle in the stroke group. PTDmin in stroke patients showed moderate to high correlations with gait speed and observational gait scale. PTDmin adequately reflected gait quality without being affected by apparent improvements due to frontal compensatory patterns. Our results showed that various impairments and compensations were included in the inability to shorten PTD, which can provide new perspectives on gait rehabilitation in stroke patients.

The effect of ankle-foot orthosis on ankle kinematics in individuals after stroke: A systematic review and meta-analysis

OBJECTIVE

To evaluate whether ankle-foot orthosis (AFO) has a beneficial effect on dorsiflexion angle increase during the swing phase among individuals with stroke and patient-important outcomes in individuals with stroke.

LITERATURE SURVEY

Randomized controlled trials (RCTs), randomized crossover trials, and cluster RCTs until May 2020 were researched through CENTRAL, MEDLINE, EMBASE, PEDro, CINAHL, and REHABDATA databases. Studies reporting on AFO use to improve walking, functional mobility, quality of life, and activity limitations and reports of adverse events in individuals with stroke were included.

METHODOLOGY

Two independent reviewers extracted the data and assessed the risk of bias. The certainty of evidence was assessed using the Grading of Recommendations, Assessment, Development and Evaluations approach.

SYNTHESIS

Fourteen trials that enrolled 282 individuals with stroke and compared AFO with no AFO were included. Compared with no AFO, AFO could increase the dorsiflexion angle of ankle joints during walking (mean difference [MD, 3.7°]; 95% confidence interval [CI], 2.0-5.3; low certainty of evidence). Furthermore, AFO could improve walking ability (walking speed) (MD, 0.09 [m/s]; 95% CI, 0.06-0.12; low certainty of evidence). No study had reported the effects of AFO on quality of life, adverse events, fall frequency, and activities of daily life.

CONCLUSIONS

Our findings suggest that AFO improved ankle kinematics and walking ability in the short term; nonetheless, the evidence was characterized by a low degree of certainty.

Machine learning analysis to predict the need for ankle foot orthosis in patients with stroke

We investigated the potential of machine learning techniques, at an early stage after stroke, to predict the need for ankle–foot orthosis (AFO) in stroke patients. We retrospectively recruited 474 consecutive stroke patients. The need for AFO during ambulation (output variable) was classified according to the Medical Research Council (MRC) score for the ankle dorsiflexor of the affected limb. Patients with an MRC score of < 3 for the ankle dorsiflexor of the affected side were considered to require AFO, while those with scores ≥ 3 were considered not to require AFO. The following demographic and clinical data collected when patients were transferred to the rehabilitation unit (16.20 ± 6.02 days) and 6 months after stroke onset were used as input data: age, sex, type of stroke (ischemic/hemorrhagic), motor evoked potential data on the tibialis anterior muscle of the affected side, modified Brunnstrom classification, functional ambulation category, MRC score for muscle strength for shoulder abduction, elbow flexion, finger flexion, finger extension, hip flexion, knee extension, and ankle dorsiflexion of the affected side. For the deep neural network model, the area under the curve (AUC) was 0.887. For the random forest and logistic regression models, the AUC was 0.855 and 0.845, respectively. Our findings demonstrate that machine learning algorithms, particularly the deep neural network, are useful for predicting the need for AFO in stroke patients during the recovery phase.

Machine learning classifies predictive kinematic features in a mouse model of neurodegeneration

Motor deficits are observed in Alzheimer's disease (AD) prior to the appearance of cognitive symptoms. To investigate the role of amyloid proteins in gait disturbances, we characterized locomotion in APP-overexpressing transgenic J20 mice. We used three-dimensional motion capture to characterize quadrupedal locomotion on a treadmill in J20 and wild-type mice. Sixteen J20 mice and fifteen wild-type mice were studied at two ages (4- and 13-month). A random forest (RF) classification algorithm discriminated between the genotypes within each age group using a leave-one-out cross-validation. The balanced accuracy of the RF classification was 92.3 ± 5.2% and 93.3 ± 4.5% as well as False Negative Rate (FNR) of 0.0 ± 0.0% and 0.0 ± 0.0% for the 4-month and 13-month groups, respectively. Feature ranking algorithms identified kinematic features that when considered simultaneously, achieved high genotype classification accuracy. The identified features demonstrated an age-specific kinematic profile of the impact of APP-overexpression. Trunk tilt and unstable hip movement patterns were important in classifying the 4-month J20 mice, whereas patterns of shoulder and iliac crest movement were critical for classifying 13-month J20 mice. Examining multiple kinematic features of gait simultaneously could also be developed to classify motor disorders in humans.

Validity of quantitative assessment of posterior pelvic tilt and contralateral vaulting in hemiplegia using 3D treadmill gait analysis

BACKGROUND

Assessing abnormal gait patterns could indicate compensatory movements, which could be an index for recovery and a process of motor learning. To quantify the degree of posterior pelvic tilt, contralateral vaulting is necessary.

OBJECTIVES

This study aimed to develop and evaluate the validity of quantitative indices for posterior pelvic tilt and contralateral vaulting in hemiplegic patients.

METHODS

Forty-six healthy control subjects and 112 hemiplegic patients participated in this study. Of the 112 patients, 50 were selected into each abnormal gait pattern group, with some overlap. Three experienced physical therapists observed their walking and graded the severity of the two abnormalities in five levels. An index to quantify each of the two abnormal gait patterns was calculated from the three-dimensional treadmill gait analysis. The index values of patients were compared with those of healthy subjects and with the results of observational gait assessment done by three physical therapists with expertise in gait analysis.

RESULTS

The index values were significantly higher in hemiplegic patients than in healthy subjects (28.0% and 44.7% for the posterior pelvic tilt in healthy subjects and patients, respectively and 0.9 and 4.7 for the contralateral vaulting, respectively). A strong correlation was observed between the index value and the median observational rating for two abnormal gait patterns (r = -0.68 and -0.72).

CONCLUSIONS

The proposed indices for posterior pelvic tilt and contralateral vaulting are useful for clinical gait analysis, and thus encouraging a more detailed analysis of hemiplegic gait using a motion analysis system.

Effect of ankle-foot orthosis on level walking in healthy subjects

An ankle-foot orthosis is often prescribed in the rehabilitation of patients with neurological motor disorders such as hemiparesis. However, walking with a unilateral ankle-foot orthosis may not be effectively achieved just by trying to reproduce normal intact walking with a symmetrical gait pattern. Understanding skills to facilitate walking gait with a unilateral ankle-foot orthosis has implications for better rehabilitative interventions to help restore walking ability in patients with stroke. We, therefore, analyzed the kinematics and ground reaction forces of walking with and without an ankle-foot orthosis in healthy subjects to infer the possible skills to facilitate walking gait with a unilateral ankle-foot orthosis. Adult male participants were asked to walk with and without an ankle-foot orthosis across two force platforms set in a wooden walkway, and body kinematics and ground reaction force profiles in the sagittal plane were simultaneously recorded. We found that the forward tilting angle of the trunk at the time of toe-off of the leg with the ankle-foot orthosis was significantly larger than that of the leg without the ankle-foot orthosis, to adaptively compensate for the loss of ankle joint mobility due to the unilateral ankle-foot orthosis. Furthermore, the peak vertical ground reaction force at heel-contact was significantly larger in the leg without the ankle-foot orthosis than in the leg with the ankle-foot orthosis owing to the fact that the stance phase duration of the leg with the ankle-foot orthosis was relatively shorter. Such information may potentially be applied to facilitate walking training in stroke patients wearing a unilateral ankle-foot orthosis.

The effect of using Gait Exercise Assist Robot (GEAR) on gait pattern in stroke patients: a cross-sectional pilot study

Background: The Gait Exercise Assist Robot (GEAR) has been developed to support gait training for stroke patients. The GEAR can assist paretic lower limb swing and stance stability, which make it possible to practice walking without excessive compensation movements. However, there are no studies to-date that investigate the effect of the GEAR on gait pattern.Objectives: The purpose of this study was to clarify the effect of gait training on gait pattern using the GEAR for rehabilitation in stroke patients.Methods: Fifteen hemiplegic patients who received gait training using the GEAR were recruited (GEAR group). As a control group, hemiplegic patients who did not receive gait training using the GEAR were selected for each patient in the GEAR group from 114 cases in our hospital database. Primary outcomes were index values indicating the degree of 10 abnormal gait patterns. Secondary outcomes were spatiotemporal factors and comfortable overground gait velocity.Results: Index values for abnormal gait patterns were significantly lower in the GEAR group compared to the control group for insufficient knee flexion during the swing phase, hip hiking, and excessive lateral shift of the trunk over the unaffected-side (p < .05). The comfortable overground gait velocity, stride length, and unaffected-step length in the GEAR group were significantly better than in the control group (p < .05).Conclusions: Gait training using the GEAR had effects on reducing abnormal gait patterns and improving gait velocity, stride, and unaffected-side step length compared to conventional gait training alone in individuals recovering from stroke-induced hemiplegia.

[Assessment of walking function in neurological practice]

An accurate diagnosis of the existing defect of motor function in patients with neurological pathology is necessary for the optimal formulation of the rehabilitation program, selection of drug therapy and evaluation of the effectiveness of treatment. In current clinical practice, clinical scales such as the Dynamic Gait Index, the Rivermid Mobility Index, the Hauser Walk Index, the Stand Up and Go Test, the MDS-UPDRS III are used most often to assess walking function. Evaluation of walking function using valid scales is very accessible, however, it has such a disadvantage as subjectivity. That's why the study of motor functions by instrumental methods gains more prominence. The most well-known methods of objective walking assessment include an analysis of human movements using accelerometers, three-dimensional video analysis, sub-metric, goniometric and impregnation methods. Each of these methods has both advantages and disadvantages. The main requirement to objective methods of assessing walking functions in neurological pathology is the universality of the complex (the accuracy of measurements, regardless of the type of walking disorder), the ability to determine both temporal and spatial characteristics of the step, the ease of use. Considering these requirements, the use of the 'Induction Analyzer of the kinematic parameters of walking' seems promising in the diagnosis of motor disorders.

A Review on the Control of the Mechanical Properties of Ankle Foot Orthosis for Gait Assistance

In the past decade, advanced technologies in robotics have been explored to enhance the rehabilitation of post-stroke patients. Previous works have shown that gait assistance for post-stroke patients can be provided through the use of robotics technology in ancillary equipment, such as Ankle Foot Orthosis (AFO). An AFO is usually used to assist patients with spasticity or foot drop problems. There are several types of AFOs, depending on the flexibility of the joint, such as rigid, flexible rigid, and articulated AFOs. A rigid AFO has a fixed joint, and a flexible rigid AFO has a more flexible joint, while the articulated AFO has a freely rotating ankle joint, where the mechanical properties of the AFO are more controllable compared to the other two types of AFOs. This paper reviews the control of the mechanical properties of existing AFOs for gait assistance in post-stroke patients. Several aspects that affect the control of the mechanical properties of an AFO, such as the controller input, number of gait phases, controller output reference, and controller performance evaluation are discussed and compared. Thus, this paper will be of interest to AFO researchers or developers who would like to design their own AFOs with the most suitable mechanical properties based on their application. The controller input and the number of gait phases are discussed first. Then, the discussion moves forward to the methods of estimating the controller output reference, which is the main focus of this study. Based on the estimation method, the gait control strategies can be classified into subject-oriented estimations and phase-oriented estimations. Finally, suggestions for future studies are addressed, one of which is the application of the adaptive controller output reference to maximize the benefits of the AFO to users.