Use of the Gait Deviation Index and spatiotemporal variables for the assessment of dual task interference paradigm

Muscle synergies analysis shows altered neural strategies in women with patellofemoral pain during walking

Several studies suggest that the central nervous system coordinates muscle activation by modulating neural commands directed to groups of muscles combined to form muscle synergies. Individuals with patellofemoral pain (PFP) move differently from asymptomatic individuals. Understanding the neural strategies involved in the execution of tasks such as walking can help comprehend how the movement is planned and better understand this clinical condition. The objective of this study was to compare muscle synergies between women with and without PFP during walking. Eleven women with PFP and thirteen asymptomatic women were assessed using three-dimensional kinematics and electromyography (EMG) while walking at self-selected speed. Kinematics of the trunk, pelvis and lower limbs were analyzed through the Movement Deviation Profile. Muscle synergies were extracted from the EMG signals of eight lower limb muscles collected throughout the whole gait cycle. Kinematic differences between the two groups (p<0.001, z-score = 3.06) were more evident during loading response, terminal stance, and pre-swing. PFP group presented a lower number of muscle synergies (p = 0.037), and greater variability accounted for (VAFtotal) when using 3 (p = 0.017), 4 (p = 0.004), and 5 (p = 0.012) synergies to reconstruct all EMG signals. The PFP group also presented higher VAFmuscle for rectus femoris (p = 0.048) and gastrocnemius medialis (p = 0.019) when considering 4 synergies. Our results suggest that women with PFP show lower motor complexity and deficit in muscle coordination to execute gait, indicating that gait in PFP is the result of different neural commands compared to asymptomatic women.

Derivation of the Gait Deviation Index for Spinal Cord Injury

The Gait Deviation Index (GDI) is a dimensionless multivariate measure of overall gait pathology represented as a single score that indicates the gait deviation from a normal gait average. It is calculated using kinematic data recorded during a three-dimensional gait analysis and an orthonormal vectorial basis with 15 gait features that was originally obtained using singular value decomposition and feature analysis on a dataset of children with cerebral palsy. Ever since, it has been used as an outcome measure to study gait in several conditions, including spinal cord injury (SCI). Nevertheless, the validity of implementing the GDI in a population with SCI has not been studied yet. We investigate the application of these mathematical methods to derive a similar metric but with a dataset of adults with SCI (SCI-GDI). The new SCI-GDI is compared with the original GDI to evaluate their differences and assess the need for a specific GDI for SCI and with the WISCI II to evaluate its sensibility. Our findings show that a 21-feature basis is necessary to account for most of the variance in gait patterns in the SCI population and to provide high-quality reconstructions of the gait curves included in the dataset and in foreign data. Furthermore, using only the first 15 features of our SCI basis, the fidelity of the reconstructions obtained in our population is higher than that when using the basis of the original GDI. The results showed that the SCI-GDI discriminates most levels of the WISCI II scale, except for levels 12 and 18. Statistically significant differences were found between both indexes within each WISCI II level except for 12, 20, and the control group (p < 0.05). In all levels, the average GDI value was greater than the average SCI-GDI value, but the difference between both indexes is larger in data with greater impairment and it reduces progressively toward a normal gait pattern. In conclusion, the implementation of the original GDI in SCI may lead to overestimation of gait function, and our new SCI-GDI is more sensitive to larger gait impairment than the GDI. Further validation of the SCI-GDI with other scales validated in SCI is needed.

Application of the Gait Deviation Index to Study Gait Impairment in Adult Population With Spinal Cord Injury: Comparison With the Walking Index for Spinal Cord Injury Levels

The Gait Deviation Index (GDI) is a multivariate measure of overall gait pathology based on 15 gait features derived from three-dimensional (3D) kinematic data. GDI aims at providing a comprehensive, easy to interpret, and clinically meaningful metric of overall gait function. It has been used as an outcome measure to study gait in several conditions: cerebral palsy (CP), post-stroke hemiparetic gait, Duchenne muscular dystrophy, and Parkinson’s disease, among others. Nevertheless, its use in population with Spinal Cord Injury (SCI) has not been studied yet. The aim of the present study was to investigate the applicability of the GDI to SCI through the assessment of the relationship of the GDI with the Walking Index for Spinal Cord Injury (WISCI) II. 3D gait kinematics of 34 patients with incomplete SCI (iSCI) was obtained. Besides, 3D gait kinematics of a sample of 50 healthy volunteers (HV) was also gathered with Codamotion motion capture system. A total of 302 (iSCI) and 446 (HV) strides were collected. GDI was calculated for each stride and grouped for each WISCI II level. HV data were analyzed as an additional set. Normal distribution for each group was assessed with Kolmogorov-Smirnov tests. Afterward, ANOVA tests were performed between each pair of WISCI II levels to identify differences among groups (p < 0.05). The results showed that the GDI was normally distributed across all WISCI II levels in both iSCI and HV groups. Furthermore, our results showed an increasing relationship between the GDI values and WISCI II levels in subjects with iSCI, but only discriminative in WISCI II levels 13, 19, and 20. The index successfully distinguished HV group from all the individuals with iSCI. Findings of this study indicated that the GDI is not an appropriate multivariate walking metric to represent the deviation of gait pattern in adult population with iSCI from a normal gait profile when it is compared with the levels of walking impairment described by the WISCI II. Future work should aim at defining and validating an overall gait index derived from 3D kinematic gait variables appropriate for SCI, additionally taking into account other walking ability outcome measures.

Application of the Gait Deviation Index in the analysis of post-stroke hemiparetic gait

Due to the complexity and volume of kinematic data from 3-dimensional gait analysis, the Gait Deviation Index (GDI) was introduced as a summary measure providing a global picture of gait kinematic data, however previously it was not validated as an outcome measure in individuals after stroke. The present study investigated the concurrent validity of the GDI as an outcome measure of gait defects at a chronic stage of recovery post-stroke, through comparisons with conventional measures of gait. Those enrolled included 65 individuals after stroke and 65 healthy individuals without gait disorders, matched for age and gender. The kinematic gait parameters were measured using a movement analysis system. Walking speed, walking distance, number of steps, self-reliant mobility, cadence, step length, and single support time were evaluated. Strong correlation was found between cadence and mGDI as well as GDI for the affected leg (0.7 ≤ |R| < 0.9; p < 0.001). Moderate correlations were found between walking speed, number of steps, step length affected leg and mGDI as well as GDI for the affected leg (0.5 ≤ |R| < 0.7; p < 0.001). Low correlations were found between walking distance, self-reliant mobility, single support time affected leg and mGDI as well as GDI for the affected leg (0.3 ≤ |R| < 0.5; p < 0.001; p < 0.005). The findings confirm the concurrent validity of the GDI, but only for the affected leg and mGDI in post-stroke patients. On the other hand, the GDI for unaffected leg may be useful in efforts to identify any compensatory mechanisms developing in post-stroke gait patterns. Trial registration: anzctr.org.au, ID:ACTRN12617000436370. Registered 24 March 2017.

Are we supererestimating gait assessments of patients with idiopathic normal-pressure hydrocephalus?

INTRODUCTION

Idiopathic normal pressure hydrocephalus (iNPH) is a syndrome characterized by a triad composed of cognitive alteration, urinary incontinence, and gait impairment associated with ventricular enlargement and normal cerebrospinal fluid pressure. Gait impairment is among the earliest symptoms; however, the reliability of the evaluation is not well-established and no consensus has been reaching regarding variables that should be analyzed and which parameters should be considered to accurately assess post-intervention improvement.

RESEARCH QUESTION

Are the degree of repeatability, standard error of measurement, and minimum detectable change considered to detect changes in gait variables in iNPH patients?

METHODS

A total of 84 iNPH patients with a mean age of 77.1 (±6.4) years were analyzed. Gait deviation index (GDI), speed, cadence, cycle time, stride length, single support, and first and second double support were chosen as the variables to be analyzed. Statistical analysis was performed by an independent evaluator, with gait repeatability assessed by the intraclass correlation coefficient (ICC) and the standard error of measure (SEM).

RESULTS

ICC values were 0.76-0.85 with excellent repeatability, while SEM demonstrated that the variables with best repeatability were the GDI (mean, 4.94; 95% confidence interval (CI), 4.63-5.43), representing a 7.65% mean relative error of the measurement (mean, 0.05 m; 95% CI, 0.05-0.06), and stride length (mean 0.05 m; 95% CI, 0.05-0.06), with a 7.69% mean relative error.

SIGNIFICANCE

We concluded that GDI and stride length were the variables with the best repeatability and lower variability in the gait of iNPH patients.

Reliability and Minimum Detectable Change of the Gait Deviation Index (GDI) in post-stroke patients

The Gait Deviation Index (GDI) is a summary measure that provides a global picture of gait kinematic data. Since the ability to walk is critical for post-stroke patients, the aim of this study was to determine the reliability and Minimum Detectable Change (MDC) of the GDI in this patient population. Twenty post-stroke patients (11 males, 9 females; mean age, 55.2±9.9years) participated in this study. Patients presented with either right- (n=14) or left-sided (n=6) hemiparesis. Kinematic gait data were collected in two sessions (test and retest) that were 2 to 7days apart. GDI values in the first and second sessions were, respectively, 59.0±8.1 and 60.2±9.4 for the paretic limb and 53.3±8.3 and 53.4±8.3 for the non-paretic limb. The reliability in each session was determined by the intra-class correlation coefficient (ICC) of three strides and, in the test session, their values were 0.91 and 0.97 for the paretic and non-paretic limbs, respectively. Between-session reliability and MDC were determined using the average GDI of three strides from each session. For the paretic limb, between-session ICC, standard error of measurement (SEM), and MDC were 0.84, 3.4 and 9.4, respectively. Non paretic lower limb exhibited between-session ICC, standard error of measurement (SEM), and MDC of 0.89, 2.7 and 7.5, respectively. These MDC values indicate that very large changes in GDI are required to identify gait improvement. Therefore, the clinical usefulness of GDI with stroke patients is questionable.

Non-MTC gait cycles: An adaptive toe trajectory control strategy in older adults

Minimum-toe-clearance (MTC) above the walking surface is a critical representation of toe-trajectory control due to its association with tripping risk. Not all gait cycles exhibit a clearly defined MTC within the swing phase but there have been few previous accounts of the biomechanical characteristics of non-MTC gait cycles. The present report investigated the within-subject non-MTC gait cycle characteristics of 15 older adults (mean 73.1 years) and 15 young controls (mean 26.1 years). Participants performed the following tasks on a motorized treadmill: preferred speed walking, dual task walking (carrying a glass of water) and a dual-task speed-matched control. Toe position-time coordinates were acquired using a 3 dimensional motion capture system. When MTC was present, toe height at MTC (MTC_height) was extracted. The proportion of non-MTC gait cycles was computed for the age groups and individuals. For non-MTC gait cycles an 'indicative' toe height at the individual's average swing phase time (MTC_time) for observed MTC cycles was averaged across multiple non-MTC gait cycles. In preferred-speed walking Young demonstrated 2.9% non-MTC gait cycles and Older 18.7%. In constrained walking conditions both groups increased non-MTC gait cycles and some older adults revealed over 90%, confirming non-MTC gait cycles as an ageing-related phenomenon in lower limb trajectory control. For all participants median indicative toe-height on non-MTC gait cycles was greater than median MTC_height. This result suggests that eliminating the biomechanically hazardous MTC event by adopting more of the higher-clearance non-MTC gait cycles, is adaptive in reducing the likelihood of toe-ground contact.

Gait profile score and movement analysis profile in patients with Parkinson's disease during concurrent cognitive load

Background:

Gait disorders are common in individuals with Parkinson's Disease (PD) and the concurrent performance of motor and cognitive tasks can have marked effects on gait. The Gait Profile Score (GPS) and the Movement Analysis Profile (MAP) were developed in order to summarize the data of kinematics and facilitate understanding of the results of gait analysis.

Objective:

To investigate the effectiveness of the GPS and MAP in the quantification of changes in gait during a concurrent cognitive load while walking in adults with and without PD.

Method:

Fourteen patients with idiopathic PD and nine healthy subjects participated in the study. All subjects performed single and dual walking tasks. The GPS/MAP was computed from three-dimensional gait analysis data.

Results:

Differences were found between tasks for GPS (P<0.05) and Gait Variable Score (GVS) (pelvic rotation, knee flexion-extension and ankle dorsiflexion-plantarflexion) (P<0.05) in the PD group. An interaction between task and group was observed for GPS (P<0.01) for the right side (Cohen's ¯d=0.99), left side (Cohen's ¯d=0.91), and overall (Cohen's ¯d=0.88). No interaction was observed only for hip internal-external rotation and foot internal-external progression GVS variables in the PD group.

Conclusions:

The results showed gait impairment during the dual task and suggest that GPS/MAP may be used to evaluate the effects of concurrent cognitive load while walking in patients with PD.

Effects of gastrocnemius fascia lengthening on gait pattern in children with cerebral palsy using the gait profile score

The aim of the present study was to investigate the efficacy of the GPS regarding the quantification of changes in gait following the gastrocnemius fascia lengthening in children with CP. Nineteen children with CP were selected and evaluated in the preoperative period (PRE session) and approximately one year postoperatively (POST session; mean 13.1 ± 5.1 months) using 3D gait analysis and computing the GPS and GVSs. As the GPS represents the difference between the patient's data and the average from the reference dataset, the higher the value of GPS is, more compromised gait of the subject. A statistically significant improvement in mean GPS was found in the POST session (PRE: 13.38 ± 5°; POST: 10.26 ± 2.41°; p<0.05), with an improvement close to 23%. Moreover, the GVSs demonstrated statistically significant improvements in ankle dorsi-plantarflexion (PRE: 22.20 ± 16.36°; POST: 11.50 ± 6.57°; p<0.05) and pelvic rotation (PRE: 9.53 ± 3.87°; POST: 6.47 ± 2.98°; p<0.05). A strong correlation (r=0.75; p<0.05) was found between the preoperative GPS and the percentage of GPS improvement. The results demonstrated that the gastrocnemius fascia lengthening produced a global gait pattern improvement, as showed by the GPS value, which decreased after surgery. Besides this, the GVS permitted to better evidence the joints more compromised by the pathology and their improvement due to the surgery, in this case not only the GVS of the ankle joint but also of the pelvis were characterized by higher GVS values.

An investigation of the value of tridimensional kinematic analysis in functional diagnosis of lumbar spinal stenosis

Diagnosis of lumbar spinal stenosis (LSS) is based on clinical examination and imaging. The aim of this study was to evaluate the influence of 3D gait analysis as a tool in the differential diagnosis of LSS. Fourteen patients participated in the study that consisted of three phases: (1) capture six gait cycles after rest, (2) walk on a treadmill for a maximum of 20 min, (3) capture six gait cycles after effort. From these data, the kinematic variables were compared with the perception of pain and the cross sectional area of the spinal canal as measured by magnetic resonance. Most of correlations were weak and showed that the most significant results are reported by the Gait Deviation Index (GDI). The Gait Deviation Index demonstrated moderate negative correlation with the perception of pain after effort was made by both limbs. This means that there is a significant decrease in the overall function of the lower limbs according to the increase in pain symptoms. This situation may be reflected in decreased cadence and speed beyond the times of single support for the left limb, and the balance of the right limb, as part of a strategy to protect against pain and imbalance. We found no correlation between gait and pain in the cross-sectional area of the spinal canal. Therefore, we believe that there is no advantage for the patient to make a 3-D gait analysis because the analysis does not add relevant information to clinical diagnosis.