Polio survivors have poorer walking adaptability than healthy individuals

Cross-step detection using center-of-pressure based algorithm for real-time applications

BACKGROUND

Gait event detection is crucial for assessment, evaluation and provision of biofeedback during rehabilitation of walking. Existing online gait event detection algorithms mostly rely on add-on sensors, limiting their practicality. Instrumented treadmills offer a promising alternative by utilizing the Center of Pressure (CoP) signal for real-time gait event detection. However, current methods have limitations, particularly in detecting cross-step events during perturbed walking conditions.

METHODS

We present and validate a CoP-based algorithm to detect gait events and cross-steps in real-time, which combines thresholding and logic techniques. The algorithm was evaluated on CoP datasets from healthy participants (age range 21-61 years), stroke survivors (age range 20-67 years), and people with unilateral transtibial amputation (age range 28-63 years) that underwent perturbation-based balance assessments, encompassing different walking speeds. Detected gait events from a simulated real-time processing operation were compared to offline identified counterparts in order to present related temporal absolute mean errors (AME) and success rate.

RESULTS

The proposed algorithm demonstrated high accuracy in detecting gait events during native gait, as well as cross-step events during perturbed walking conditions. It successfully recognized the majority of cross-steps, with a detection success rate of 94%. However, some misclassifications or missed events occurred, mainly due to the complexity of cross-step events. AME for heel strikes (HS) during native gait and cross-step events averaged at 78 ms and 64 ms respectively, while toe off (TO) AME were 126 ms and 111 ms respectively. A statistically significant difference in the algorithm's success rate score in detecting gait events during cross-step intervals was observed across various walking speeds in a sample of 12 healthy participants, while there was no significant difference among groups.

CONCLUSION

The proposed algorithm represents an advancement in gait event detection on instrumented treadmills. By leveraging the CoP signal, it successfully identifies gait events and cross-steps in the simulated real-time processing operation, providing valuable insights into human locomotion. The algorithm's ability to accommodate diverse CoP patterns enhance its applicability to a wide range of individuals and gait characteristics. The algorithm's performance was consistent across different populations, suggesting its potential for diverse clinical and research settings, particularly in the domains of gait analysis and rehabilitation practices.

Machine learning-based gait adaptation dysfunction identification using CMill-based gait data

Background

Combining machine learning (ML) with gait analysis is widely applicable for diagnosing abnormal gait patterns.

Objective

To analyze gait adaptability characteristics in stroke patients, develop ML models to identify individuals with GAD, and select optimal diagnostic models and key classification features.

Methods

This study was investigated with 30 stroke patients (mean age 42.69 years, 60% male) and 50 healthy adults (mean age 41.34 years, 58% male). Gait adaptability was assessed using a CMill treadmill on gait adaptation tasks: target stepping, slalom walking, obstacle avoidance, and speed adaptation. The preliminary analysis of variables in both groups was conducted using t-tests and Pearson correlation. Features were extracted from demographics, gait kinematics, and gait adaptability datasets. ML models based on Support Vector Machine, Decision Tree, Multi-layer Perceptron, K-Nearest Neighbors, and AdaCost algorithm were trained to classify individuals with and without GAD. Model performance was evaluated using accuracy (ACC), sensitivity (SEN), F1-score and the area under the receiver operating characteristic (ROC) curve (AUC).

Results

The stroke group showed a significantly decreased gait speed (p = 0.000) and step length (SL) (p = 0.000), while the asymmetry of SL (p = 0.000) and ST (p = 0.000) was higher compared to the healthy group. The gait adaptation tasks significantly decreased in slalom walking (p = 0.000), obstacle avoidance (p = 0.000), and speed adaptation (p = 0.000). Gait speed (p = 0.000) and obstacle avoidance (p = 0.000) were significantly correlated with global F-A score in stroke patients. The AdaCost demonstrated better classification performance with an ACC of 0.85, SEN of 0.80, F1-score of 0.77, and ROC-AUC of 0.75. Obstacle avoidance and gait speed were identified as critical features in this model.

Conclusion

Stroke patients walk slower with shorter SL and more asymmetry of SL and ST. Their gait adaptability was decreased, particularly in obstacle avoidance and speed adaptation. The faster gait speed and better obstacle avoidance were correlated with better functional mobility. The AdaCost identifies individuals with GAD and facilitates clinical decision-making. This advances the future development of user-friendly interfaces and computer-aided diagnosis systems.

Two-year course of walking adaptability in persons living with late effects of polio

OBJECTIVE

To evaluate the 2-year course of walking adaptability in persons with late effects of polio.

DESIGN

Prospective cohort study.

PATIENTS

A total of 48 persons with late effects of polio (69% female, mean age 63.1 years) with a fall history and/or fear of falling.

METHODS

Walking adaptability (i.e. variable target-stepping and reactive obstacle-avoidance) was assessed on an interactive treadmill at baseline, 1 year and 2 years. Further, leg-muscle strength and balance were assessed at baseline. The course of walking adaptability was analysed with linear mixed models. Based on median values, subgroups were defined for low vs high baseline walking-adaptability and for clinical characteristics. Tme by subgroup interactions were analysed.

RESULTS

Variable target-stepping and reactive obstacle-avoidance did not change (p > 0.285). Reactive obstacle-avoidance improved for persons with a high balance score at baseline (p = 0.037), but not for those with lower scores (p = 0.531). No other time by subgroup interactions were found (p > 0.126).

CONCLUSION

Walking adaptability did not change in persons with late effects of polio over 2 years, and walking adaptability course did not differ between subgroups stratified for walking adaptability determinants, except for balance. Since falls are a major problem among persons with late effects of polio, future studies should investigate whether walking adaptability declines over a longer time and which persons are most at risk.

Effects of gait adaptation training on augmented reality treadmill for patients with stroke in community ambulation

Gait adaptability is essential for stroke survivors to achieve efficient and safe community ambulation. However, conventional treadmill rehabilitation is only a repetitive practice of leg movement. This study compared the effects of augmented reality treadmill-based gait adaptation training with regular treadmill programs for patients with stroke. Forty patients with stroke (n = 40) were randomly assigned to the gait adaptation training {n = 20, age: 49.85 [standard deviation (SD) 8.44] years; onset of stroke: 107.80 (SD 48.31) days} and regular training [n = 20, age: 50.75 (SD 8.05) years, onset of stroke: 111.60 (SD 49.62) days] groups. Both groups completed three sessions of training per week for 5 weeks (15 sessions). The primary outcomes were the 10-m walk test and success rate of obstacle avoidance, while secondary outcomes included the Berg balance scale, component timed-up-and-go, and fall rate in a 6-month follow-up period. Assessments were performed before and after the intervention. The paired t-test was applied to compare the differences within groups and independent sample t-test was performed to compare the differences between groups. The 10-m walk test, success rate of obstacle avoidance, Berg balance scale, and component timed-up-and-go all significantly improved in the both groups (P < .001). The success rate of obstacle avoidance [P = .02, 95% confidence interval (CI): -21.07, -1.64], Berg Balance Scale (P = .02, 95% CI: -8.03, -0.67), 'turning around time' (P = .04, 95% CI: 0.08, 2.81), 'stand-to-sit' (P = .03, 95% CI: 0.16, 2.41) and 'total time' (P = .048, 95% CI: 0.04, 10.32) improved significantly in gait adaptation training group after intervention, while the 10-m walk test (P = .09, 95% CI: -0.17, 0.01), timed 'sit-to-stand' (P = .09, 95% CI: -0.14, 2.04), and 'linear walking' (P = .09, 95% CI: -0.27, 3.25) in gait adaptation training group did not show statistical difference compared to the regular training group. Total fall rate during the follow-up period was statistically decreased in the gait adaptation training group (P = .045). Both interventions improved mobility outcomes, with augmented reality treadmill-based gait adaptation indicating greater improvement in obstacle avoidance, balance, turning, and stand-to-sit. Augmented reality treadmill-based gait adaptation training emerges as an effective and promising intervention for patients with stroke in early rehabilitation.

Safety, walking ability, and satisfaction outcomes of the NEURO TRONIC stance-control knee-ankle-foot orthosis (SCKAFO): A comparative evaluation to the E-MAG active SCKAFO

BACKGROUND

Stance control knee-ankle-foot orthoses (SCKAFOs) ensure knee stability by locking during stance while allowing knee flexion during swing. Differences in function of the knee joints and building principles between devices may affect their effectiveness.

OBJECTIVE

To investigate the preliminary effectiveness of a NEURO TRONIC on safety outcomes, net energy cost (EC), and user experiences in individuals already using an E-MAG Active SCKAFO.

STUDY DESIGN

Prospective uncontrolled intervention study.

METHODS

A convenience sample of 10 subjects with flaccid lower extremity muscle weakness, including the quadriceps, due to neuromuscular disorders already using an E-MAG Active SCKAFO were provided with a newly fabricated NEURO TRONIC SCKAFO. Outcomes included knee joint locking failures and unlocking failures (ULFs) (i.e., percentage of steps the knee joint failed to lock/unlock) when walking under challenging conditions on an instrumented treadmill while wearing a safety harness; net EC (J/kg per meter) assessed with a 6-min walk test at comfortable speed; 3D gait kinematics and kinetics; and patient-reported outcomes.

RESULTS

No differences between devices were found for knee joint locking failures (both devices 0%) and ULFs (9.9% for the NEURO TRONIC vs. 13.9% for the E-MAG Active SCKAFO). The mean (standard deviation) net EC with the NEURO TRONIC SCKAFO was 8.2% (from 3.68 [0.81] to 3.38 [0.75] J/kg per meter, p = 0.123) lower, although not significantly, compared with that with the E-MAG Active SCKAFO. Significant improvements with the NEURO TRONIC SCKAFO were found for ankle power ( p = 0.003), perceived walking effort ( p = 0.014), and reported falls ( p = 0.034).

CONCLUSION

Both the NEURO TRONIC SCKAFO and the E-MAG Active SCKAFO were safe in terms of knee joint locking, while ULFs were frequent with both devices. The net EC with the NEURO TRONIC SCKAFO decreased, although not significantly, by 8.2%, likely due to insufficient power. Perceived walking effort was in favor of the NEURO TRONIC SCKAFO.

Gait stability and the relationship with energy cost of walking in polio survivors with unilateral plantarflexor weakness

BACKGROUND

Polio survivors often exhibit plantarflexor weakness, which impairs gait stability, and increases energy cost of walking. Quantifying gait stability could provide insights in the control mechanisms polio survivors use to maintain gait stability and in whether impaired gait stability is related to the increased energy cost of walking.

RESEARCH QUESTION

Is gait stability impaired in polio survivors with plantarflexor weakness compared to able-bodied individuals, and does gait stability relate to energy cost of walking?

METHODS

We retrospectively analyzed barefoot biomechanical gait data of 31 polio survivors with unilateral plantarflexor weakness and of 24 able-bodied individuals. We estimated gait stability by calculating variability (SD) of step width, step length, double support time, and stance time, and by the mean and variability (SD) of the mediolateral and anteroposterior margin of stability (MoSML and MoSAP). In addition, energy cost of walking (polio survivors only) at comfortable speed was analyzed.

RESULTS

Comfortable speed was 31% lower in polio survivors compared to able-bodied individuals (p < 0.001). Corrected for speed differences, step width variability was significantly larger in polio survivors (+41%), double support time variability was significantly smaller (-27%), MoSML (affected leg) was significantly larger (+80%), and MoSAP was significantly smaller (affected leg:-17% and non-affected leg:-15%). Step width and step length variability (affected leg) were positively correlated with energy cost of walking (r = 0.502 and r = 0.552). MoSAP (non-affected leg) was negatively correlated with energy cost of walking (r = -0.530).

SIGNIFICANCE

Polio survivors with unilateral plantarflexor weakness demonstrated an impaired gait stability. Increased step width and step length variability and lower MoSAP could be factors related to the elevated energy cost of walking in polio survivors. These findings increase our understanding of stability problems due to plantarflexor weakness, which could be used for the improvement of (orthotic) interventions to enhance gait stability and reduce energy cost in polio survivors.

Walking with shorter stride length could improve knee kinetics of patients with medial knee osteoarthritis

Walking with a shorter stride length (SL) was recently proposed for gait retraining in medial knee osteoarthritis; however it was never assessed in this patient population. This study tested the hypothesis that shortening SL while maintaining walking speed reduces knee adduction (KAM) and flexion (KFM) moments in patients with medial knee osteoarthritis. Walking trials with normal SL and SL reduced by 0.10 m and 0.15 m were recorded for 15 patients (10 men, 55.5 ± 8.7 years old, 24.6 ± 3.0 kg/m²). SL was modified using an augmented reality system displaying target footprints on the floor. Repeated one-way ANOVAs and post-hoc paired t-tests were performed to compare gait measures between normal and reduced SL. The individual effects of SL reduction were analyzed using descriptive statistics. Group analysis indicated significant decreases in KAM impulse with both SL reductions (p < 0.05). No systematic change was observed in the first peaks KAM and KFM when walking with reduced SL (p > 0.05). Individually, 33 % of the patients decreased the peak KAM, whereas 20 % decreased the KAM impulse. Among these patients with a decrease in peak KAM or in KAM impulse, 0 % and 33 % had a simultaneous increase in peak KFM, respectively. In conclusion, this study showed that SL shortening can decrease kinetic measures associated with the progression of medial knee osteoarthritis in some patients, demonstrating the importance of considering SL modifications on an individual basis. While further research is necessary, notably regarding dose-response relationships and long-term effects, these findings are particularly encouraging because SL reductions could be easily integrated into rehabilitation protocols.

Validity and reproducibility of C-Mill walking-adaptability assessment in polio survivors

BACKGROUND

The C-Mill interactive treadmill allows for a safe walking-adaptability assessment, unveiling reduced walking adaptability in polio survivors compared to healthy individuals, possibly related to their high fall rate. However, evidence on its validity and reproducibility is scarce.

RESEARCH QUESTION

What is the validity and reproducibility of C-Mill walking-adaptability assessment in polio survivors?

METHODS

Polio survivors with a history and/or fear of falling (n = 46) performed two walking-adaptability assessments, 1-2 weeks apart, including target-stepping tests (with 0%, 20% and 30% inter-target variance) and obstacle-avoidance tests (anticipatory and reactive). We examined (1) face validity by determining Group effects (for subgroups stratified for fall frequency, fear of falling and leg muscle weakness) and Condition effects (for difficulty level) on walking-adaptability outcomes, (2) construct validity by correlating walking-adaptability and balance outcomes, and (3) content validity by establishing possible ceiling effects. We determined whether face-validity findings were reproducible over test occasions and calculated Intraclass Correlation Coefficients (ICC) and the 95% Limits of Agreement (LoA) for walking-adaptability outcomes.

RESULTS

Walking-adaptability outcomes differed in to-be-expected directions for subgroups stratified for fall frequency and leg muscle weakness and for difficulty levels, all reproducible over test occasions. Correlations between walking-adaptability and balance outcomes were mainly low (r < 0.587). Ceiling effects were present for anticipatory obstacle-avoidance and balance outcomes, but not for reactive obstacle avoidance. ICCs [95% confidence intervals] were good for the challenging 20% (0.80[0.67-0.88]) and 30% target-stepping conditions (0.74[0.57-0.85]) and for the reactive obstacle-avoidance (0.76[0.59-0.86]) condition, but not for 0% target-stepping and anticipatory obstacle-avoidance (ICC<0.62) conditions. Likewise, the narrowest LoA were observed for the 20% and 30% target-stepping conditions.

SIGNIFICANCE

We proved face, construct and content validity of C-Mill walking-adaptability assessment in polio survivors with a history of falls and/or fear of falling. Adding walking-adaptability assessment, particularly the more challenging tests given their superior reproducibility, to currently used clinical tests could improve fall-risk evaluation in this population.