Gait velocity control using projection mapping for children with spastic diplegia cerebral palsy

BACKGROUND

Gait characteristics in children with cerebral palsy vary according to their individual walking speed. As such, establishing methods to maintain a consistent gait velocity are necessary to evaluate specific intervention effects in this clinical population. Our study aim was to validate the accuracy of projection mapping for guiding gait velocity to a control gait velocity.

METHODS

This was a cross-sectional study of 13 children with cerebral palsy (mean age [standard deviation] of 12.42 [2.31] years). The target velocity was calculated from the average speed obtained across three trials of self-selected walking speed. A virtual reality system with four projectors was used to project an image onto the floor to guide children to match two gait conditions: 100% and 125% velocity of the average speed. Participants completed three gait trials at each velocity under image guidance. Gait velocity was quantified using a 3-dimensional motion capture system. Bland-Altman plots were used to analyze systematic errors and the limits of agreement calculated.

FINDINGS

The results indicated the limits of agreement were acceptable for 0.10 m/s for 100% velocity and 0.12 m/s for 125% velocity. Therefore, projection mapping was effective in guiding children to adjust their gait to the intended velocity.

INTERPRETATION

Projection mapping is a novel method for guiding children with cerebral palsy to walk at a controlled target velocity that may improve the reliability of gait analysis.

Minimal clinically important difference in walking velocity, gait profile score and two minute walk test for individuals with lower limb amputation

BACKGROUND

Individuals with lower limb amputation are routinely assessed with a variety outcome measures, however there is a lack of published data to indicate minimal clinically important differences (MCID) for many of these outcome measures. Three such important gait-specific outcome measures include walking velocity, gait profile score (GPS) and the two minute walk test (2MWT).

RESEARCH QUESTION

Determine the MCIDs for walking velocity, GPS and 2MWT for individuals with lower limb amputation.

METHODS

Walking velocity and GPS (n = 60), and 2MWT (n = 119) data for individuals with unilateral transfemoral or knee disarticulation were identified retrospectively from a database held at the study centre. An anchor-based method was used with Medicare functional classification level (MFCL) acting as the impairment-related criterion, and a least-squares linear regression approach was used to calculate the gradient required for a change between MFCL levels.

RESULTS

An increase of 0.21 m/s (95 % CI: 0.13,0.29) for walking velocity, a reduction of 1.7° (95 % CI: -2.449,-1.097) for GPS and an increase of 37.2 m (95 % CI: 28.8,45.5) for 2MWT were found to correspond to an increase in MFCL of one level. Walking velocity, GPS and 2MWT correlated with MFCL with R² values of 0.333, 0.322 and 0.398 respectively (p < 0.00001). The authors propose that 0.21 m/s for walking velocity, 1.7° for GPS and 37.2 m for 2MWT be used as MCID values for individuals with lower limb amputation.

SIGNIFICANCE

The results of this study can be used to help both researchers and clinicians to objectively evaluate if interventions for individuals with lower limb amputation are effective.

Comparison of measurement protocols to estimate preferred walking speed between sites

BACKGROUND

Walking speed influences a variety of typical outcome measures in gait analysis. Many researchers use a participant's preferred walking speed (PWS) during gait analysis with a goal of trying to capture how a participant would typically walk. However, the best practices for estimating PWS and the impact of laboratory size and walk distance are still unclear.

RESEARCH QUESTION

Is measured PWS consistent across different distances and between two laboratory sites?

METHODS

Participants walked overground at a "comfortable speed" for six different conditions with either dynamic (4, 6, 10, and 400 m) or static (4 and 10 m) starts and stops at two different data collection sites. Repeated measures ANOVA with Bonferroni corrections were used to test for differences between conditions and sites.

RESULTS

Participants walked significantly faster in the 4, 6, and 10 m dynamic conditions than in the 400 m condition. On average, participants walked slower in the static trials than the dynamic trials of the same distance. There was a significant interaction of lab and condition and so results were examined within each lab. Across both labs, we found that the 4 and 10 m dynamic conditions were not different than the 6 m dynamic condition at both sites, while other tests did not provide consistent results at both sites.

SIGNIFICANCE

We recommend researchers use a 6 m distance with acceleration and deceleration zones to reliably test for PWS across different laboratories. Given some of the differences found between conditions that varied by site, we also emphasize the need to report the test environment and methods used to estimate PWS in all future studies so that the methods can be replicated between studies.

The influence of trunk muscle strength on walking velocity in elderly people with sarcopenia

[Purpose] Sarcopenia increases the risk of falls and fractures. However, its relationship with walking, which is the generation mechanism of falls, has not been clarified. The purpose of this study was to clarify the trunk muscle strength and the characteristics of walking, in elderly people with sarcopenia. [Participants and Methods] The participants were 40 elderly people aged 65 years and over. The participants were able to walk without assistance and were attending outpatient rehabilitation or community day-care centers. The assessment and measurement items included: the presence or absence of sarcopenia (using the diagnostic criteria of the Asian Working Group for Sarcopenia), lower limb and trunk muscle strength, and characteristics of walking. The participants were divided into two groups depending on the presence or absence of sarcopenia, and a comparison was made between the two groups. [Results] The participants in the sarcopenia group had significantly lower trunk extension muscle strength as compared to the participants in the non-sarcopenia group. In addition, the hip joint maximum flexion moment, ankle joint maximum plantar flexion moment, and walking velocity of participants in the sarcopenia group were significantly lower than those in the non-sarcopenia group. [Conclusion] This study revealed that weakness of the trunk muscle strength causes a decrease in walking velocity in elderly people with sarcopenia.

Reactive gait and postural adjustments following the first exposures to (un)expected stepdown

This study evaluated the reactive biomechanical strategies associated with both upper- and lower-body (lead and trail limbs) following the first exposures to (un)expected stepdown at comfortable (1.22 ± 0.08 m/s) and fast (1.71 ± 0.11 m/s) walking velocities. Eleven healthy adults completed 34 trails per walking velocity over an 8-m, custom-built track with two forceplates embedded in its center. For the expected stepdown, the track was lowered by 0-, -10- and -20-cm from the site of the second forceplate, whereas the unexpected stepdown was created by camouflaging the second forceplate (-10-cm). Two-way repeated-measurement ANOVAs detected no velocity-related effects of stepdown on kinematic and kinetic parameters during lead limb stance-phase, and on the trail limb stepping kinematics. However, analyses of significant interactions revealed greater peak flexion angles across the trunk and the trail limb joints (hip, knee and ankle) in unexpected versus expected stepdown conditions at a faster walking velocity. The -10-cm unexpected stepdown (main effect) had a greater influence on locomotor behavior compared to expected conditions due mainly to the absence of predictive adjustments, reflected by a significant decrease in peak knee flexion, contact time and vertical impulse during stance-phase. Walking faster (main effect) was associated with an increase in hip peak flexion and net anteroposterior impulse, and a decrease in contact time and vertical impulse during stepdown. The trail limb, in response, swung forward faster, generating a larger and faster recovery step. However, such reactive stepping following unexpected stepdown was yet a sparse compensation for an unstable body configuration, assessed by significantly smaller step width and anteroposterior margin-of-stability at foot-contact in the first-recovery-step compared with expected conditions. These findings depict the impact of the expectedness of stepdown onset on modulation of global dynamic postural control for a successful accommodation of (un)expected surface elevation changes in young, healthy adults.

Reducing gait speed affects axial coordination of walking turns

Turning is a common feature of daily life and dynamic coordination of the axial body segments is a cornerstone for safe and efficient turning. Although slow walking speed is a common trait of old age and neurological disorders, little is known about the effect of walking speed on axial coordination during walking turns. The aim of this study was to investigate the influence of walking speed on axial coordination during walking turns in healthy elderly adults. Seventeen healthy elderly adults randomly performed 180° left and right turns while walking in their self-selected comfortable pace and in a slow pace speed. Turning velocity, spatiotemporal gait parameters (step length and step time), angular rotations and angular velocity of the head and pelvis, head-pelvis separation (i.e. the angular difference in degrees between the rotation of the head and pelvis) and head-pelvis velocity were analyzed using Wilcoxon signed-rank tests. During slow walking, turning velocity was 15% lower accompanied by shorter step length and longer step time compared to comfortable walking. Reducing walking speed also led to a decrease in the amplitude and velocity of the axial rotation of the head and pelvis as well as a reduced head-pelvis separation and angular velocity. This study demonstrates that axial coordination during turning is speed dependent as evidenced by a more 'en bloc' movement pattern (i.e. less separation between axial segments) at reduced speeds in healthy older adults. This emphasizes the need for matching speed when comparing groups with diverse walking speeds to differentiate changes due to speed from changes due to disease.

Effect of investigator observation on gait parameters in individuals with and without chronic low back pain

Despite the ubiquity of gait assessment in clinic and research, it is unclear how observation impacts gait, particularly in persons with chronic pain and psychological stress. We compared temporal spatial gait patterns in people with and without chronic low back pain (CLBP) when they were aware and unaware of being observed. This was a repeated-measures, deception study in 55 healthy persons (32.0±12.4 yr, 24.2±2.7kg/m²) and persons with CLBP (51.9±17.9 yr, 27.8±4.4kg/m²). Participants performed one condition in which they were unaware of observation (UNW), and three conditions under investigator observation: (1) aware of observation (AWA), (2) investigators watching cadence, (3) investigators watching step length. Participants walked across an 8.4m gait mat, while temporal spatial parameters of gait were collected. The Medical Outcomes Short Form (SF-12), Beck Depression Inventory (BDI), State Trait Anxiety Inventory (STAI), and Oswestry Disability Index (ODI) were completed. Significant condition by group interactions were found for velocity and step length (p<0.05). Main effects of study condition existed for all gait variables except for step width. Main effects of group (healthy, LBP) were significant for all variables except for step width (p<0.05). Regression analyses revealed that after accounting for age, sex, and SF-12 mental component score, BDI scores predict velocity changes during walking from the UNW to AWA conditions. These findings show that people change their gait patterns when being observed. Gait analyses may require additional trials before data can reliably be interpreted and used for clinical decision-making.

Can we unmask features of spasticity during gait in children with cerebral palsy by increasing their walking velocity?

BACKGROUND AND AIM

Spasticity is a velocity dependent feature present in most patients with cerebral palsy (CP). It is commonly measured in a passive condition. The aim of this study was to highlight markers of spasticity of gastrocnemius and hamstring muscles during gait by comparing the effect of increased walking velocity of CP and typical developing (TD) children.

METHODS

53 children with spastic CP and 17 TD children were instructed to walk at self-selected speed, faster and as fast as possible without running. Kinematics, kinetics and electromyography (EMG) were collected and muscle length and muscle lengthening velocity (MLV) were calculated. To compare the data of both groups, a linear regression model was created which resulted in two non-dimensional gait velocities. A difference score (DS) was calculated between the high and low velocity values for both groups.

RESULTS

103 gait parameters were analyzed of which 16 had a statistically significant DS between TD and CP groups. The spastic gastrocnemius muscle presented at high velocity with a higher ankle angular velocity, plantar flexion moment, power absorption and increased EMG signal during loading response. The spastic hamstrings demonstrated at high velocity a delayed maximum knee extension moment at mid-stance and increasing hip extension moment and hip power generation. The hamstrings also presented with a lower MLV during swing phase.

CONCLUSIONS

A limited number of gait parameters differ between CP and TD children when increasing walking velocity, giving indirect insight on the effect of spasticity on gait.

Effect of gait speed changes on foot loading characteristics in children

Gait speed has been shown to influence foot loading patterns in adults but the mechanism has not been investigated in children. The present study investigated the effects of changes in gait speed on foot loading characteristics in 20 typically developing children who participated in plantar pressure measurements at normal, slow and fast walking speeds. In spite of shorter contact times in the fast walking speed condition, significantly increased foot loading was seen in the hindfoot, medial and central forefoot and toes while it slightly decreased in the lateral midfoot and forefoot. The results generally confirm the findings in adults that gait speed does not uniformly affect foot loading characteristics and that these effects should be kept in mind when comparing different subject groups or children at repeated measurement occasions.