Walking velocity and lower limb coordination in hemiparesis

Kinetic and kinematic parameters associated with late braking force and effects on gait performance of stroke patients

Late braking force (LBF) is often observed in the late stance phase of the paretic lower limb of stroke patients. Nevertheless, the effects and association of LBF remain unclear. We examined the kinetic and kinematic parameters associated with LBF and its effect on walking. Herein, 157 stroke patients were enrolled. Participants walked at a comfortable speed selected by them, and their movements were measured using a 3D motion analysis system. The effect of LBF was analyzed as a linear relationship with spatiotemporal parameters. Multiple linear regression analyses were performed with LBF as the dependent variable and kinetic and kinematic parameters as independent variables. LBF was observed in 110 patients. LBF was associated with decreased knee joint flexion angles during the pre-swing and swing phases. In the multivariate analysis, trailing limb angle, cooperativity between the paretic shank and foot, and cooperativity between the paretic and non-paretic thighs were related to LBF (p < 0.01; adjusted R² = 0.64). LBF in the late stance phase of the paretic lower limb reduced gait performance in the pre-swing and swing phases. LBF was associated with trailing limb angle in the late stance, coordination between the paretic shank and foot in the pre-swing phase, and coordination between both thighs.

Effects of aging on arm coordination at different walking speeds

BACKGROUND

Previous work has shown that the mean continuous relative phase and coordination variability of lower limbs are modified in older adults when walking.

RESEARCH QUESTION

Here, we propose to understand the extent to which such control mechanisms for upper limbs are present during gait. Specifically, we seek to understand if aging and gait speed constraints influence the interjoint control of upper limbs during walking.

METHODS

This observational study evaluated thirty-three participants, divided into older (n = 20, age 66.4 ± 4.3 years; mass: 77.2 ± 14.2 kg; height: 165 ± 9.20 cm) and young adults (n = 13, age 29.5 ± 4.7 years; mass 75.5 ± 9.6 kg; height: 172 ± 6.24 cm) were asked to walk at 0.28, 0.83, 1.38 m.s^-1 on a level treadmill while their segmental movements were simultaneously registered with 3D motion capture system. We calculated the mean continuous relative phase and coordination variability (continuous relative phase variability) in elbow-shoulder and shoulder-hip pairs, and a generalized estimating equation was used to test the main and interaction effects of age and speed.

RESULTS

Older adults had a reduced continuous relative phase (more in-phase coordination) of upper limbs at whole stance for elbow-shoulder, at loading response for shoulder-hip, at mid-stance and terminal stance for elbow-shoulder and shoulder-hip in comparison to young adults at different speeds (p < 0.05). The coordination variability of upper limbs was greater (higher continuous relative phase variability) in older than young adults at 0.28 and 1.38 m.s^-1.

SIGNIFICANCE

These findings substantiate the altered motor control role of upper limbs in gait aging, suggesting that lower self-selected speed may be related to the reduced ability to control arm movement during the intermediate phases of gait.

Acute effects of Kinesio Taping on lower-limb coordination of gait in hemiplegic patients

BACKGROUND

Kinesio taping can effectively strengthen weakened muscles, increase walking speed, and improve dynamic balance in hemiplegic patients, but its effect on lower-limb coordination is not clear. Improving lower-limb coordination in hemiplegic patients can decrease risk of fall during walking.

RESEARCH QUESTION

This study utilized continuous relative phase to depict the pattern and variability of lower-limb coordination in hemiplegic patients and healthy subjects during walking, and investigate whether it has the acute effect of Kinesio Taping on lower-limb coordination in hemiplegic patients during walking.

METHODS

Gait was measured by a three-dimensional motion capture system for 29 hemiplegic patients (KT group) and 15 healthy subjects (control group). Mean continuous relative phase (MCRP) and mean continuous relative phase variability (MCRPV) were calculated to describe and evaluate lower-limb coordination.

RESULTS

KT intervention only changed the coordination between the bilateral ankle joints in hemiplegic patients. Before the intervention, the MCRP of the two ankles (AA-MCRP) in the stance period of the control group was greater than the KT group (P < 0.001), the MCRPV of the two ankles (AA-MCRPV) in the swing period was lower than that in KT group (P < 0.001). After the intervention, the AA-MCRP in the stance period of the KT group increased (P < 0.001), the AA-MRPV in the swing period of KT group significantly decreased (P = 0.001).

SIGNIFICANCE

Immediate ankle KT intervention can result in the in-phase or anti-phase coordination between the two ankles developing to out-of-phase coordination during the stance period of the affected limb during walking, and increase the stability of the out-of-phase coordination between the two ankles during the swing period of the affected limb. KT can be used in rehabilitation treatment for hemiplegic patients to improve acute coordination between the patients' ankles.

Gait Synergy Analysis and Modeling on Amputees and Stroke Patients for Lower Limb Assistive Devices

The concept of synergy has drawn attention and been applied to lower limb assistive devices such as exoskeletons and prostheses for improving human–machine interaction. A better understanding of the influence of gait kinematics on synergies and a better synergy-modeling method are important for device design and improvement. To this end, gait data from healthy, amputee, and stroke subjects were collected. First, continuous relative phase (CRP) was used to quantify their synergies and explore the influence of kinematics. Second, long short-term memory (LSTM) and principal component analysis (PCA) were adopted to model interlimb synergy and intralimb synergy, respectively. The results indicate that the limited hip and knee range of motions (RoMs) in stroke patients and amputees significantly influence their synergies in different ways. In interlimb synergy modeling, LSTM (RMSE: 0.798° (hip) and 1.963° (knee)) has lower errors than PCA (RMSE: 5.050° (hip) and 10.353° (knee)), which is frequently used in the literature. Further, in intralimb synergy modeling, LSTM (RMSE: 3.894°) enables better synergy modeling than PCA (RMSE: 10.312°). In conclusion, stroke patients and amputees perform different compensatory mechanisms to adapt to new interlimb and intralimb synergies different from healthy people. LSTM has better synergy modeling and shows a promise for generating trajectories in line with the wearer’s motion for lower limb assistive devices.

Walking Speed Alters Barefoot Gait Coordination and Variability

Using the dynamic system approach, we examined the pattern and variability of inter-joint coordination in barefoot and shod walking in 20 women at three speeds: SLOW, FAST, and comfortable walking speed (CWS). We found that barefoot and shod walking used different coordination strategies to cope with increasing walking speed. As walking speed increased, ankle-knee coordination patterns between shod and barefoot became less different (p < 0.00001), and ankle-hip coordination patterns became more different (p < 0.001). Compared to shod, barefoot walking had significantly lower coordination variability in mid stance of knee-hip at CWS and FAST and late swing of ankle-hip at SLOW and CWS with medium effect (effect size 0.61-0.74). Future research should investigate the connection between the decreased coordination variability and joint tissue stress to understand the impact of barefoot walking on the lower extremity joints.

Effects of various walking intensities on leg muscle fatigue and plantar pressure distributions

Background

Physical activity may benefit health and reduce risk for chronic complications in normal and people with diabetes and peripheral vascular diseases. However, it is unclear whether leg muscle fatigue after weight-bearing physical activities, such as brisk walking, may increase risk for plantar tissue injury. In the literature, there is no evidence on the effect of muscle fatigue on plantar pressure after various walking intensities. The objectives of this study were to investigate the effects of various walking intensities on leg muscle fatigue and plantar pressure patterns.

Methods

A 3 × 2 factorial design, including 3 walking speeds (1.8 (slow and normal walking), 3.6 (brisk walking), and 5.4 (slow running) mph) and 2 walking durations (10 and 20 min) for a total of 6 walking intensities, was tested in 12 healthy participants in 3 consecutive weeks. The median frequency and complexity of electromyographic (EMG) signals of tibialis anterior (TA) and gastrocnemius medialis (GM) were used to quantify muscle fatigue. Fourier transform was used to compute the median frequency and multiscale entropy was used to calculate complexity of EMG signals. Peak plantar pressure (PPP) values at the 4 plantar regions (big toe, first metatarsal head, second metatarsal head, and heel) were calculated.

Results

Two-way ANOVA showed that the walking speed (at 1.8, 3.6, 5.4 mph) significantly affected leg muscle fatigue, and the duration factor (at 10 and 20 min) did not. The one-way ANOVA showed that there were four significant pairwise differences of the median frequency of TA, including walking speed of 1.8 and 3.6 mph (185.7 ± 6.1 vs. 164.9 ± 3.0 Hz, P = 0.006) and 1.8 and 5.4 mph (185.7 ± 6.1 vs. 164.5 ± 5.5 Hz, P = 0.006) for the 10-min duration; and walking speed of 1.8 and 3.6 mph (180.0 ± 5.9 vs. 163.1 ± 4.4 Hz, P = 0.024) and 1.8 and 5.4 mph (180.0 ± 5.9 vs. 162.8 ± 4.9 Hz, P = 0.023) for the 20-min duration. The complexity of TA showed a similar trend with the median frequency of TA. The median frequency of TA has a significant negative correlation with PPP on the big toe ( r = -0.954, P = 0.003) and the first metatarsal head ( r = -0.896, P = 0.016).

Conclusions

This study demonstrated that brisk walking and slow running speeds (3.6 and 5.4 mph) cause an increase in muscle fatigue of TA compared to slow walking speed (1.8 mph); and the increased muscle fatigue is significantly related to a higher PPP.

Decoding of Motor Coordination Imagery Involving the Lower Limbs by the EEG-Based Brain Network

Compared with the efficacy of traditional physical therapy, a new therapy utilizing motor imagery can induce brain plasticity and allows partial recovery of motor ability in patients with hemiplegia after stroke. Here, we proposed an updated paradigm utilizing motor coordination imagery involving the lower limbs (normal gait imagery and hemiplegic gait imagery after stroke) and decoded such imagery via an electroencephalogram- (EEG-) based brain network. Thirty subjects were recruited to collect EEGs during motor coordination imagery involving the lower limbs. Time-domain analysis, power spectrum analysis, time-frequency analysis, brain network analysis, and statistical analysis were used to explore the neural mechanisms of motor coordination imagery involving the lower limbs. Then, EEG-based brain network features were extracted, and a support vector machine was used for decoding. The results showed that the two employed motor coordination imageries mainly activated sensorimotor areas; the frequency band power was mainly concentrated within theta and alpha bands, and brain functional connections mainly occurred in the right forehead. The combination of the network attributes of the EEG-based brain network and the spatial features of the adjacency matrix had good separability for the two kinds of gait imagery (p < 0.05), and the average classification accuracy of the combination feature was 92.96% ± 7.54%. Taken together, our findings suggest that brain network features can be used to identify normal gait imagery and hemiplegic gait imagery after stroke.

Carrying Asymmetric Loads While Walking on a Treadmill Interferes with Lower Limb Coordination

The purpose of this study was to investigate the effect of different load carriage modes on coordinative patterns in the lower extremities during walking. Twenty-five university students walked on a treadmill at their preferred pace under three different load conditions: symmetric load (5% of body mass in messenger bags on each shoulder hanging vertically and against the hips), asymmetric load 1 (10% of body mass in a messenger bag on one shoulder hanging vertically against the ipsilateral hip), and asymmetric load 2 (10% of body mass in a messenger bag on one shoulder with the bag draped across the trunk to the contralateral hip). Altered thigh-shank and shank-foot couplings were found for the loaded side during the stance of gait when comparing the asymmetric 1 and 2 to the symmetric load. In addition, thigh-thigh coupling was changed during gait when comparing the asymmetric load 2 and symmetric load. However, we did not find any significant differences in intralimb and interlimb couplings between the two different asymmetric load conditions. The results suggest potential benefits when carrying symmetrical loads in order to decrease abnormal limb coordination in daily activities. Thus, it may be advisable to distribute load more symmetrically to avoid abnormal gait.

Goal Attainment: A Clinically Meaningful Measure of Success of Botulinum Toxin-A Treatment for Lower Limb Spasticity in Ambulatory Patients

Objectives

The objectives of this study were to evaluate whether botulinum toxin type A (BoNT-A) treatment for lower limb spasticity leads to patient goal attainment and identify factors associated with positive goal attainment and to assess the effect of BoNT-A treatment on patients’ gait.

Design

Retrospective cohort study between June 2014 and February 2019.

Setting

Public outpatient spasticity clinic in a tertiary hospital.

Participants

Thirty patients (N=30; 50% female; average age, 50.5y) with lower limb spasticity of heterogenous etiologies (96.7% cerebral±spinal origin and 3.3% isolated spinal origin); 73.3% (N=22) of patients had previously received BoNT-A treatment.

Interventions

BoNT-A injection to lower limb muscles.

Main Outcome Measures

The primary outcome measure was goal attainment measured using Goal Attainment Scaling. The Modified Ashworth Scale (MAS) was used to assess spasticity. Gait was characterized by spatiotemporal parameters.

Results

Fifty-six treatment episodes were analyzed and showed that BoNT-A treatment resulted in a significant reduction in spasticity (pretreatment MAS=3.18±0.73; posttreatment MAS=2.27±0.89; P<.001) with no associated change in gait parameters. Logistic regression revealed that most patients (74.1%) achieved all of their goals, with younger patients having a high likelihood of goal attainment regardless of their gait profile identified by latent profile analysis of the gait parameters. Patients considered to have a low functioning gait profile demonstrated a significantly greater likelihood of goal attainment than patients with the other gait profiles combined (odds ratio, 45.6; 95% confidence interval, 1.3-1602.1; P=.036). Chronic spasticity and pretreatment severity of spasticity (MAS) and its reduction were not associated with likelihood of goal attainment.

Conclusions

The success and efficacy of BoNT-A treatment in improving patient perceived gait quality and reducing the negative symptoms of spasticity were best measured using Goal Attainment Scaling. The study emphasizes the importance of measuring patient goals as a clinical outcome. Gait parameters were most informative when used collectively to classify patients based on their overall gait profile, which assisted in identifying differences between patients’ likelihood of goal attainment after treatment.

Associations of inter-segmental coordination and treadmill walking economy in youth with cerebral palsy

This study investigated associations of thigh-shank coordination deficit severity and metabolic demands of walking in youth with cerebral palsy (CP) and their typically developing (TD) peers. Youth (ages 8-18 years) with hemiplegic and diplegic CP [Gross Motor Classification System (GMFCS) I-III] and their age (within 12 months) and sex-matched peers performed a modified six-minute-walk-test on a treadmill. Kinematics (Motion Analysis, USA, 240 Hz) and mass-specific gross metabolic rate (GMR; COSMED, Italy) were analyzed for minute two of treadmill walking. Thigh-shank coordination was determined using continuous relative phase (CRP) analysis. GMR was normalized using participant specific Froude numbers (i.e. GMR_Eq). Maximum and minimum CRP deficit angles (CRP_Max,CRP_Min) were analysed in SPSS (IBM, USA) using paired samples t-tests with Bonferroni correction (p = 0.0125). Associations of knee extension angle deficit (KED_Max) and coordination outcomes with GMR_Eq (log) were assessed using multiple linear regression. Twenty-eight matched pairs were included, demonstrating significantly larger CRP_Max for youth with CP [GMFCS I mean pair difference (98.75%CI) 8.2 (-0.1,16.5), P = 0.013; GMFCS II/III 26.1 (2.3,50.0), P = 0.008]. Joint kinematics and coordination outcomes were significantly associated with GMR_Eq (P < 0.001), primarily due to CRP_Max (P < 0.001), leading to a 1.7 (95%CI; 1.1, 2.4)% increase in GMR_Eq for every degree increase in CRP_Max. These findings indicate an association of thigh-shank coordination deficit severity and increasing metabolic demands of walking in youth with CP. CRP may be a clinically useful predictor of metabolic demands of walking in CP. Future work will evaluate the sensitivity of CRP to coordination and walking economy changes with surgical and non-surgical management.

The effect of asymmetrical gait induced by unilateral knee brace on the knee flexor and extensor muscles

Asymmetrical stiff knee gait is a mechanical pathology that can disrupt lower extremity muscle coordination. A better understanding of this condition can help identify potential complications. This study proposes the use of dynamic musculoskeletal modelling simulation to investigate the effect of induced mechanical perturbation on the kneeand to examine the muscle behaviour without invasive technique. Thirty-eight healthy participants were recruited. Asymmetrical gait was simulated using knee brace. Knee joint angle, joint moment and knee flexor and extensor muscle forces were computed using OpenSim. Differences inmuscle force between normal and abnormal conditions were investigated using ANOVA and Tukey-Kramer multiple comparison test.The results revealed that braced knee experienced limited range of motion with smaller flexion moment occuring at late swing phase. Significant differences were found in all flexormuscle forces and in several extensor muscle forces (p<0.05). Normal knee produced larger flexor muscle force than braced knee. Braced knee generated the largest extensor muscle force at early swing phase. In summary, musculoskeletal modelling simulation can be a computational tool to map and detect the differences between normal and asymmetrical gaits.

The Effect of Repeated abobotulinumtoxinA (Dysport®) Injections on Walking Velocity in Persons with Spastic Hemiparesis Caused by Stroke or Traumatic Brain Injury

Background

Botulinum toxin (BoNT) injections were shown to improve muscle tone of limbs in patients with spasticity. However, limited data are available regarding the effects of repeated BoNT injections on walking ability.

Objective

To assess changes in walking velocity (WV), step length, and cadence under different test conditions after repeated treatment with abobotulinumtoxinA (aboBoNT‐A; Dysport) in spastic lower limb muscles.

Design

Secondary analysis of an open‐label, multiple‐cycle extension (National Clinical Trials number NCT01251367) to a phase III, double‐blind, randomized, placebo‐controlled, single‐treatment cycle study, in adults with chronic hemiparesis (NCT01249404).

Setting

Fifty‐two centers across Australia, Belgium, the Czech Republic, France, Hungary, Italy, Poland, Portugal, Russia, Slovakia, and the United States.

Patients

352 Ambulatory adults (18‐80 years) with spastic hemiparesis and gait dysfunction caused by stroke or traumatic brain injury, with a comfortable barefoot WV of 0.1 to 0.8 m/s.

Interventions

Up to four aboBoNT‐A treatment cycles, administered to spastic lower limb muscles.

Main Outcome Measurements

Changes from baseline in comfortable and maximal barefoot and with shoes WV (m/s), step length (m/step), and cadence (steps/minutes).

Results

At Week 12 after four injections, WV improved by 0.08 to 0.10 m/s, step length by 0.03 to 0.04 m/step, and cadence by 3.9 to 6.2 steps/minutes depending on test condition (all P < .0001 to .0003 vs baseline). More patients (7% to 17%) became unlimited community ambulators (WV ≥0.8 m/s) across test conditions compared with baseline, with 39% of 151 patients classified as unlimited community ambulators in at least one test condition and 17% in all four test conditions.

Conclusions

Clinically meaningful and statistically significant improvements in WV, step length, and cadence under all four test conditions were observed in patients with spastic hemiparesis after each aboBoNT‐A treatment cycle.

Lower Limb Inter-Joint Coordination of Unilateral Transfemoral Amputees: Implications for Adaptation Control

The gait of transfemoral amputees can be made smoother by adjusting the inter-joint coordination of both lower limbs. In this study, we compared the inter-joint coordination of the amputated and non-amputated limbs of unilateral amputees to able-bodied controls. Eight amputees and eight able-bodied control participants were recruited. Walking speed, stance–swing time ratio, joint angle, joint angular velocity, and inter-joint coordination parameters—including continuous relative phase (CRP) and decomposition index (DI)—of the lower-limb joint pairs in stance and swing phases were investigated. Similarity of the CRP between groups was evaluated using cross-correlation measures and root-mean-square, and the variability of the CRP was examined by deviation phase (DP). There were significant differences between the amputated limbs and controls in CRP of hip–knee and knee–ankle in stance and swing, DP of knee–ankle and hip–ankle in stance, and DI of hip–knee in swing. For the non-amputated limbs, there were significant differences in CRP and DP of knee–ankle, and DI of hip–knee in swing compared to controls. The amputees utilized unique inter-joint coordination patterns for both limbs—particularly the hip joint—to compensate for the support-capability impairment due to limb salvage and ensure foot placement accuracy.

Gait kinematics and physical function that most affect intralimb coordination in patients with stroke

BACKGROUND

Disturbed lower limb coordination is thought to limit gait ability in patients with stroke. However, the relationship of lower limb coordination with gait kinematics and physical function has not yet been clarified.

OBJECTIVE

The purpose of the study was to clarify the gait kinematic and physical function variables that most affect intralimb coordination by using the continuous relative phase (CRP) between the thigh and shank.

METHODS

Fifteen participants with stroke were enrolled in this study. Kinematic and kinetic measurements were recorded during gait at preferred speeds. CRP was defined as the difference between the thigh and shank phase angles.

RESULTS

Stepwise analysis revealed that non-paretic CRP during the propulsive phase was a determinant of gait speed. The paretic knee extension and flexion angles were determinants of the CRP during the propulsive phase in the non-paretic limb. Stepwise analysis showed that the paretic knee extension angle was a determinant of the CRP during the propulsive phase in the paretic limb. Stepwise analysis revealed that the paretic knee extensor muscle strength was a determinant of the CRP during the propulsive phase in both limbs.

CONCLUSIONS

Our study indicates that improvement in knee movement during the stance phase may improve coordination.

Effect of Common Pavements on Interjoint Coordination of Walking with and without Robotic Exoskeleton

Background

The analysis and comprehension of the coordination control of a human gait on common grounds benefit the development of robotic exoskeleton for motor recovery.

Objective

This study investigated whether the common grounds effect the interjoint coordination of healthy participants with/without exoskeletons in walking.

Methods

The knee-ankle coordination and hip-knee coordination of 8 healthy participants in a sagittal plane were measured on five kinds of pavements (tiled, carpet, wooden, concrete, and pebbled) with/without exoskeletons, using the continuous relative phase (CRP). The root mean square of CRP (CRP_RMS) over each phase of the gait cycle is used to analyze the magnitude of dephasing between joints, and the standard deviation of CRP (CRP_SD) in the full gait cycle is used to assess the variability of coordination patterns between joints.

Results

The CRP_Hip-Knee/RMS of the carpet pavement with exoskeleton is different from that of other pavements (except the tiled pavement) in the midstance phase. The CRP_Hip-Knee/RMS on the pebble pavement without exoskeleton is less than that on the other pavements in all phases. The CRP_Hip-Knee/SD of the pebble pavement without exoskeleton is smaller than that of other pavements. The CRP_{Knee-Ankle/SD} with/without exoskeleton is similar across all pavements.

Conclusion

The compressive capacity of the pavement and the unevenness of the pavement are important factors that influence interjoint coordination, which can be used as key control elements of gait to adapt different pavements for robotic exoskeleton.

Novelty

We provide a basis of parameter change of kinematics on different common grounds for the design and optimization of robotic exoskeleton for motor recovery.

Beyond speed: Gait changes after botulinum toxin injections in chronic stroke survivors (a systematic review)

BACKGROUND

The mechanisms by which spasticity reductions after botulinum toxin A (BoNT) affect gait in stroke are not well understood. We systematically reviewed the effects of BoNT on spatiotemporal, kinematic, kinetic and electromyographic (EMG) measures during gait.

QUESTION

What are the effects of botulinum toxin on gait mechanics in stroke patients?

METHODS

Systematic search using PubMed and Web of Science. We considered all studies that reported laboratory-based and instrumented gait measures as primary or secondary outcomes to determine the effects of BoNT on walking performance in stroke populations only. Selected studies were classified and analysed based on the injection sites.

RESULTS

A total of 240 articles were identified of which 22 were selected for analysis. Overall, 91% of the studies reported spatiotemporal, 64% kinematics, 23% kinetics, 32% EMG and 23% other gait measures. All but one study found significant effects of BoNT on gait measures using instrumented assessments even when clinical measures (i.e. speed) did not significantly improve. However, the majority of the studies had a high risk of bias. Overall, BoNT improved: a) dorsiflexion during stance, propulsive forces and timing and activity of more proximal musculature with injections in the plantarflexors; b) hip, knee and ankle angles and velocities, coordination and energetic cost with injections in the rectus femoris; c) segmental coordination and energetic cost when several lower limb muscles were injected; and, d) elbow and trunk angles when upper limb muscles were injected.

CONCLUSION

Instrumented and laboratory measures of gait improve after BoNT injections in different muscle groups even in the absence of clinical changes.

Adaptive Proxy-Based Controller of an Active Ankle Foot Orthosis to Assist Lower Limb Movements of Paretic Patients

This paper deals with the control of an active ankle foot orthosis (AAFO) for paretic patients. State of the art methods using an AAFO try to track a predefined trajectory of the ankle joint while guaranteeing the wearer’s safety in the presence of a large tracking error. Combining the wearer’s safety and tracking accuracy is generally difficult to achieve at the same time, hence a trade-off should be found. Proxy-based sliding mode control (PSMC) offers great performances in both position tracking and safety guarantee. However, its tracking performance is subject to the influences of parameter uncertainties and external disturbances that generally occur during walking. This paper introduces an adaptation interaction method to the basic PSMC with an online adaptation of the proportional, integral and derivative parameters. At the same time, a gait phase-based ankle reference generation algorithm was proposed to adjust the joint reference trajectory in real time. The experiments using the AAFO show better tracking results with respect to basic PSMC while guaranteeing the safety.

Effects of personal and task constraints on limb coordination during walking: A systematic review and meta-analysis

BACKGROUND

In human behaviour, emergence of movement patterns is shaped by different, interacting constraints and consequently, individuals with motor disorders usually display distinctive lower limb coordination modes.

OBJECTIVES

To review existing evidence on the effects of motor disorders and different task constraints on emergent coordination patterns during walking, and to examine the clinical significance of task constraints on gait coordination in people with motor disorders.

METHODS

The search included CINHAL Plus, MEDLINE, HSNAE, SPORTDiscus, Scopus, Pubmed and AMED. We included studies that compared intra-limb and inter-limb coordination during gait between individuals with a motor disorder and able-bodied individuals, and under different task constraints. Two reviewers independently examined the quality of studies by using the Newcastle Ottawa Scale-cohort study.

FINDINGS

From the search results, we identified 1416 articles that studied gait patterns and further analysis resulted in 33 articles for systematic review and 18 articles for meta-analysis-1, and 10 articles for meta-analysis-2. In total, the gait patterns of 539 patients and 358 able-bodied participants were analysed in the sampled studies. Results of the meta-analysis for group comparisons revealed a low effect size for group differences (ES = -0.24), and a moderate effect size for task interventions (ES = -0.53), on limb coordination during gait.

INTERPRETATION

Findings demonstrated that motor disorders can be considered as an individual constraint, significantly altering gait patterns. These findings suggest that gait should be interpreted as functional adaptation to changing personal constraints, rather than as an abnormality. Results imply that designing gait interventions, through modifying locomotion tasks, can facilitate the emergent re-organisation of inter-limb coordination patterns during rehabilitation.

Efficacy and safety of abobotulinumtoxinA in spastic lower limb: Randomized trial and extension

OBJECTIVE

To demonstrate single abobotulinumtoxinA injection efficacy in lower limb vs placebo for adults with chronic hemiparesis and assess long-term safety and efficacy of repeated injections.

METHODS

In a multicenter, double-blind, randomized, placebo-controlled, single-cycle study followed by a 1-year open-label, multiple-cycle extension, adults ≥6 months after stroke/brain injury received one lower limb injection (abobotulinumtoxinA 1,000 U, abobotulinumtoxinA 1,500 U, placebo) followed by ≤4 open-label cycles (1,000, 1,500 U) at ≥12-week intervals. Efficacy measures included Modified Ashworth Scale (MAS) in gastrocnemius-soleus complex (GSC; double-blind primary endpoint), physician global assessment (PGA), and comfortable barefoot walking speed. Safety was the open-label primary endpoint.

RESULTS

After a single injection, mean (95% confidence interval) MAS GSC changes from baseline at week 4 (double-blind, n = 381) were as follows: -0.5 (-0.7 to -0.4) (placebo, n = 128), -0.6 (-0.8 to -0.5) (abobotulinumtoxinA 1,000 U, n = 125; p = 0.28 vs placebo), and -0.8 (-0.9 to -0.7) (abobotulinumtoxinA 1,500 U, n = 128; p = 0.009 vs placebo). Mean week 4 PGA scores were as follows: 0.7 (0.5, 0.9) (placebo), 0.9 (0.7, 1.1) (1,000 U; p = 0.067 vs placebo), and 0.9 (0.7, 1.1) (1,500 U; p = 0.067); walking speed was not significantly improved vs placebo. At cycle 4, week 4 (open-label), mean MAS GSC change reached -1.0. Incremental improvements in PGA and walking speed occurred across open-label cycles; by cycle 4, week 4, mean PGA was 1.9, and walking speed increased +25.3% (17.5, 33.2), with 16% of participants walking >0.8 m/s (associated with community mobility; 0% at baseline). Tolerability was good and consistent with the known abobotulinumtoxinA safety profile.

CONCLUSIONS

In chronic hemiparesis, single abobotulinumtoxinA (Dysport Ipsen) administration reduced muscle tone. Repeated administration over a year was well-tolerated and improved walking speed and likelihood of achieving community ambulation.

CLINICALTRIALGOV IDENTIFIERS

NCT01249404, NCT01251367.

CLASSIFICATION OF EVIDENCE

The double-blind phase of this study provides Class I evidence that for adults with chronic spastic hemiparesis, a single abobotulinumtoxinA injection reduces lower extremity muscle tone.

Adaptive control of an actuated-ankle-foot-orthosis

This paper deals with the control of an active ankle foot orthosis (AAFO) to assist the gait of paretic patients. The AAFO system is driven by both, the residual human torque delivered by the muscles spanning the ankle joint and the AAFO's actuator's torque. A projection-based model reference adaptive control is proposed to assist dorsiflexion and plantar-flexion of the ankle joint during daily living walking activities. Unlike most classical model-based controllers, the proposed one does not require any prior estimation of the system's (foot-AAFO) parameters. The ankle reference trajectory was extracted from healthy subjects gait activities in a clinical environment. The input-to-state stability of the foot-AAFO system with respect to a bounded human muscular torque is proved in closed-loop based on a Lyapunov analysis. Preliminary experimental results with a healthy subject walking on a treadmill, show satisfactory results in terms of tracking performance and ankle assistance throughout the gait cycle.

Timed Up and Go test: Comparison of kinematics between patients with chronic stroke and healthy subjects

Understanding locomotor behavior is important to guide rehabilitation after stroke. This study compared lower-limb kinematics during the walking and turning sub-tasks of the Timed Up and Go (TUG) test in stroke patients and healthy subjects. We also determined the parameters which explain TUG sub-task performance time in healthy subjects. Biomechanical parameters were recorded during the TUG in standardized conditions in 25 healthy individuals and 29 patients with chronic stroke using a 3D motion-analysis system. Parameters were compared between groups and a stepwise regression was used to indicate parameters which explained performance time in the healthy subjects. The percentage difference in step length between the last and first steps was calculated, during walking sub-tasks for each group. Speed, cadence, step length, percentage paretic single support phase, percentage non-paretic swing phase, peak hip extension, knee flexion and ankle dorsiflexion were significantly reduced in the Stroke group compared to the Healthy group (p<0.05). In the Healthy group, step length and cadence explained 91% of variance for Go and 86% for Return (walking sub-tasks), and none of the parameters explained the Turn. Previous study in patients with stroke showed that the same parameters explained the variance during the walking sub-tasks and balance-related parameters explained the Turn. The present results showed that step length was differently modulated in each group. Thus the locomotor behavior of patients with stroke during obstacle circumvention is quite specific in light of the results obtained in healthy subjects.

Intersegmental coordination scales with gait speed similarly in men and women

We applied principal component analysis (PCA) to thigh, shank, and foot elevation angles to examine the impact of speed on intra-limb coordination during gait. The specific aims were to (1) determine speed-related changes in segment loadings on three principal components (PCs) and (2) examine differences between men and women. The subjects (26 women, 21 men) walked overground at five self-selected paces (very slow, slow, normal, fast, very fast). PCA yielded percent variation (PV) explained by each PC and thigh, shank, and foot loadings on PC1-PC3. These parameters were regressed against the speed normalized to body height (BH/s) to derive individual and aggregate slopes and P values, separately for men and women. PV1 increased with speed, whereas PV2 and PV3 decreased (all P < 0.001). The loadings of thigh and foot segments on PC1 increased with speed (0.14 and 0.04 per BH/s, P < 0.001, respectively), and the loading of shank decreased (-0.10, P < 0.001). Compared to PC1, the changes in segment loadings on PC3 were the opposite (thigh -0.18, shank 0.09, foot -0.04 per BH/s, P < 0.001). The changes in segment loadings on PC2 were inconsistent and generally small. The only significance (P = 0.006), albeit a minor difference between men and women, was in the slope of thigh loading on PC2 (-0.005 ± 0.019 and 0.015 ± 0.026 per BH/s, respectively). We conclude that intersegmental coordination during gait scales with speed, with the greatest impact on the thigh segment, but no differently between men and women.

Pressure-controlled treadmill training in chronic stroke: a case study with AlterG

BACKGROUND AND PURPOSE

Body-weight-supported treadmill training has been shown to be an effective intervention to improve walking characteristics for individuals who have experienced a stroke. A pressure-controlled treadmill utilizes a sealed chamber in which air pressure can be altered in a controlled manner to counteract the effects of gravity. The focus of this case study was to assess the immediate and short-term impact of a pressure-controlled treadmill to improve gait parameters, reduce fall risk, improve participation, and reduce the self-perceived negative impact of stroke in an individual with chronic stroke.

CASE DESCRIPTION

The subject was an 81-year-old man (14.5 months poststroke). He had slow walking speed, poor endurance, and multiple gait deviations.

INTERVENTION

The subject trained 4 times per week for 4 weeks (40 minutes per session) on a pressure-controlled treadmill (AlterG M320) to counter the influence of gravity on the lower extremities.

OUTCOMES

Following training, self-selected gait speed increased from 0.50 m/s to 0.96 m/s, as measured by the 10-meter walk test. Stride length increased from 0.58 m to 0.95 m after training and to 1.00 m at 1-month follow-up. Peak hip flexion increased from 3.7° to 24.6° after training and to 19.4° at 1-month follow-up. Peak knee flexion increased from 19.4° to 34.3° after training and to 42.7° at 1-month follow-up. Measures of endurance, fall risk, and percentage of perceived recovery also were found to improve posttraining.

DISCUSSION

Training with a pressure-controlled treadmill may be a viable alternative to traditional body-weight-supported treadmill training for persons poststroke. Additional studies with larger sample sizes are needed to elucidate the role of pressure-controlled treadmill training in this population. Video abstract available for more insights from the authors (see Supplemental Digital Content 1, http://links.lww.com/JNPT/A97).

Effects of quadriceps muscle fatigue on stiff-knee gait in patients with hemiparesis

The relationship between neuromuscular fatigue and locomotion has never been investigated in hemiparetic patients despite the fact that, in the clinical context, patients report to be more spastic or stiffer after walking a long distance or after a rehabilitation session. The aim of this study was to evaluate the effects of quadriceps muscle fatigue on the biomechanical gait parameters of patients with a stiff-knee gait (SKG). Thirteen patients and eleven healthy controls performed one gait analysis before a protocol of isokinetic quadriceps fatigue and two after (immediately after and after 10 minutes of rest). Spatiotemporal parameters, sagittal knee and hip kinematics, rectus femoris (RF) and vastus lateralis (VL) kinematics and electromyographic (EMG) activity were analyzed. The results showed that quadriceps muscle weakness, produced by repetitive concentric contractions of the knee extensors, induced an improvement of spatiotemporal parameters for patients and healthy subjects. For the patient group, the increase in gait velocity and step length was associated with i) an increase of sagittal hip and knee flexion during the swing phase, ii) an increase of the maximal normalized length of the RF and VL and of the maximal VL lengthening velocity during the pre-swing and swing phases, and iii) a decrease in EMG activity of the RF muscle during the initial pre-swing phase and during the latter 2/3 of the initial swing phase. These results suggest that quadriceps fatigue did not alter the gait of patients with hemiparesis walking with a SKG and that neuromuscular fatigue may play the same functional role as an anti-spastic treatment such as botulinum toxin-A injection. Strength training of knee extensors, although commonly performed in rehabilitation, does not seem to be a priority to improve gait of these patients.

Categorization of gait patterns in adults with cerebral palsy: a clustering approach

Gait patterns in adults with cerebral palsy have, to our knowledge, never been assessed. This contrasts with the large number of studies which have attempted to categorize gait patterns in children with cerebral palsy. Several methodological approaches have been developed to objectively classify gait patterns in patients with central nervous system lesions. These methods enable the identification of groups of patients with common underlying clinical problems. One method is cluster analysis, a multivariate statistical method which is used to classify an entire data set into homogeneous groups or "clusters". The aim of this study was to determine, using cluster analysis, the principal gait patterns which can be found in adults with cerebral palsy. Data from 3D motion analyses of 44 adults with cerebral palsy were included. A hierarchical cluster analysis was used to subgroup the different gait patterns based on spatiotemporal and kinematic parameters in the sagittal and frontal planes. Five clusters were identified (C1-C5) among which, 3 subgroups were determined, based on spontaneous gait speed (C1/C2: slow, C3/C4: moderate and C5: almost normal). The different clusters were related to specific kinematic parameters that can be assessed in routine clinical practice. These 5 classifications can be used to follow changes in gait patterns throughout growth and aging as well to assess the effects of different treatments (physiotherapy, surgery, botulinum toxin, etc.) on gait patterns in adults with cerebral palsy.

Variations in kinematics during clinical gait analysis in stroke patients

In addition to changes in spatio-temporal and kinematic parameters, patients with stroke exhibit fear of falling as well as fatigability during gait. These changes could compromise interpretation of data from gait analysis. The aim of this study was to determine if the gait of hemiplegic patients changes significantly over successive gait trials. Forty two stroke patients and twenty healthy subjects performed 9 gait trials during a gait analysis session. The mean and variability of spatio-temporal and kinematic joint parameters were analyzed during 3 groups of consecutive gait trials (1-3, 4-6 and 7-9). Principal component analysis was used to reduce the number of variables from the joint kinematic waveforms and to identify the parts of the gait cycle which changed during the gait analysis session. The results showed that i) spontaneous gait velocity and the other spatio-temporal parameters significantly increased, and ii) gait variability decreased, over the last 6 gait trials compared to the first 3, for hemiplegic patients but not healthy subjects. Principal component analysis revealed changes in the sagittal waveforms of the hip, knee and ankle for hemiplegic patients after the first 3 gait trials. These results suggest that at the beginning of the gait analysis session, stroke patients exhibited phase of adaptation,characterized by a "cautious gait" but no fatigue was observed.

Bilateral coordination and gait symmetry after body-weight supported treadmill training for persons with chronic stroke

BACKGROUND

Locomotor interventions are commonly assessed using functional outcomes, but these outcomes provide limited information about changes toward recovery or compensatory mechanisms. The study purposes were to examine changes in gait symmetry and bilateral coordination following body-weight supported treadmill training in individuals with chronic hemiparesis due to stroke and to compare findings to participants without disability.

METHODS

Nineteen participants with stroke (>6 months) who ambulated between 0.4 and 0.8 m/s and 22 participants without disability were enrolled in this repeated-measures study. The stroke group completed 24 intervention sessions over 8 weeks with 20 minutes of walking/session. The non-disabled group served as a comparison for describing changes in symmetry and coordination. Bilateral 3-dimensional motion analysis and gait speed were assessed across 3 time points (pre-test, immediate post-test, and 6-month retention). Continuous relative phase was used to evaluate bilateral coordination (thigh-thigh, shank-shank, foot-foot) and gait symmetry was assessed with spatiotemporal ratios (step length, swing time, stance time).

FINDINGS

Significant improvements in continuous relative phase (shank-shank and foot-foot couplings) were found at post-test and retention for the stroke group. Significant differences in spatiotemporal symmetry ratios were not found over time. Compared to the non-disabled group, changes in bilateral coordination moved in the direction of normal recovery. Most measures of continuous relative phase were more responsive to change after training than the spatiotemporal ratios.

INTERPRETATIONS

After body-weight supported treadmill training, the stroke group made improvements toward recovery of normal bilateral coordination. Bilateral coordination and gait symmetry measures may assess different aspects of gait.

Effect of botulinum toxin injection on length and lengthening velocity of rectus femoris during gait in hemiparetic patients

BACKGROUND

In hemiparetic patients, rectus femoris spasticity is one of the main causes of reduced knee flexion in swing phase, known as stiff knee gait. Botulinum toxin is often used to reduce rectus femoris spasticity and to increase knee flexion during swing phase. However, the mechanisms behind these improvements remain poorly understood. The aim of this study was (1) to quantify maximal rectus femoris length and lengthening velocity during gait in ten adult hemiparetic subjects with rectus femoris spasticity and stiff knee gait and to compare these parameters with those of ten healthy subjects and (2) to study the effect of botulinum toxin injection in the rectus femoris muscle on the same parameters.

METHODS

10 patients with stiff knee gait and rectus femoris spasticity underwent 3D gait analysis before and one month after botulinum toxin injection of the rectus femoris (200 U Botox, Allergan Inc., Markham, Ontario, CANADA). Rectus femoris length and lengthening velocity were quantified using a musculoskeletal model (SIMM, MusculoGraphics, Inc., Santa Rosa, California, USA).

FINDINGS

Maximal length and lengthening velocity of the rectus femoris were significantly reduced on the paretic side. There was a significant increase in muscle length as well as lengthening velocity during gait following botulinum toxin injection.

INTERPRETATION

This study showed that botulinum toxin injection in the spastic rectus femoris of hemiparetic patients improves muscle kinematics during gait. However maximal rectus femoris length did not reach normal values following injection, suggesting that other mechanisms are likely involved.