The Gait Deviation Index: a new comprehensive index of gait pathology

This article describes a new multivariate measure of overall gait pathology called the Gait Deviation Index (GDI). The first step in developing the GDI was to use kinematic data from a large number of walking strides to derive a set of mutually independent joint rotation patterns that efficiently describe gait. These patterns are called gait features. Linear combinations of the first 15 gait features produced a 98% faithful reconstruction of both the data from which they were derived and 1000 validation strides not used in the derivation. The GDI was then defined as a scaled distance between the 15 gait feature scores for a subject and the average of the same 15 gait feature scores for a control group of typically developing (TD) children. Concurrent and face validity data for the GDI are presented through comparisons with the Gillette Gait Index (GGI), Gillette Functional Assessment Questionnaire Walking Scale (FAQ), and topographic classifications within the diagnosis of Cerebral Palsy (CP). The GDI and GGI are strongly correlated (r(2)=0.56). The GDI scales with FAQ level, distinguishes levels from one another, and is normally distributed across FAQ levels six to ten and among TD children. The GDI also scales with respect to clinical involvement based on topographic CP classification in Hemiplegia Types I-IV, Diplegia, Triplegia and Quadriplegia. The GDI offers an alternative to the GGI as a comprehensive quantitative gait pathology index, and can be readily computed using the electronic addendum provided with this article.     

Intersite variations of the Gillette Gait Index

The Gillette Gait Index (GGI) is a tool used to measure pathologic gait severity and assess outcomes. The purpose of this study is to assess the variation in calculated GGI values with different sets of control data. Five able bodied control sets from four labs were used to establish the basis of the GGI. Gait data from three pediatric patients seen pre- and post-operatively at one lab and one adult control subject that visited each lab were input to calculate GGI values. Differences in underlying control data created large differences in computed GGI values for both pathologic and able bodied subjects. Initial pre-operative GGI values calculated for the three patients with cerebral palsy using different control data sets varied widely with differences as large as 1129 and had magnitudes of improvement differing by as much as 800 (or 21%). GGI value differences greater than 250 were determined from an able bodied control subject seen at each lab, both when examining a single trial with different control sets, and when examining different trials of the same individual collected from different labs using a single control set. These results highlight the importance of the underlying control set for establishing mean values and variance in the GGI and suggest that if GGI values are compared longitudinally or between sites these comparisons should be based on a single control dataset.     

Gait analysis in children and uncertainty assessment for Davis protocol and Gillette Gait Index

The protocol of Davis is widely used in children's gait analysis, especially in cerebral palsy studies and its repeatability was evaluated primarily for adults. The aim of this research was to evaluate the uncertainty and repeatability of this protocol for children. 56 asymptomatic children aged 5–15 years performed the gait exam. Kinematics parameters and Gillette Gait Index (GGI) were calculated. 17 subjects performed the exam twice with markers replacement. Uncertainties on gait parameters were evaluated using repeatability study and Monte Carlo simulations. Uncertainty (2SD of test–retest differences) obtained on angles calculated by the protocol varied between ±2° and ±3° (for pelvis and hip in sagittal and frontal planes) and ±14° (for mean hip rotation). Uncertainty on GGI was ±12 for healthy subjects. Monte Carlo simulations on 30 cerebral palsy children showed that the error on GGI could reach ±100 and was correlated to GGI value (R² = 0.92): 2SD = 24 + 0.09 × GGI.     

Construct validity of the Wisconsin Gait Scale in acute,subacute and chronic stroke

ObjectiveTo assess the construct validity of the Wisconsin Gait Scale (WGS) in subjects after stroke.MethodsA retrospective observational study was conducted at inpatient rehabilitation hospital. Data from 61 stroke patients was compiled. The Functional Ambulatory Categories (FAC), the Berg Balance Scale (BBS), the Postural Assessment Scale for Stroke Patients (PASS), the Barthel Index (BI) and the Functional Independence Measure (FIM) were selected to analyze the WGS construct validity at four specific time points after stroke (acute, subacute and chronic stages). Spearman correlation coefficients investigated the relationship between WGS and clinical measures.ResultsThe construct validity of the WGS in patients with stroke at acute stage was moderate with the FAC (r=−.773), the BBS (r=−.676), the PASS (r=−.646) and the FIM (r=−.592). At subacute stage, the construct validity of the WGS was excellent with the FAC (r=−878), the BBS (r=−.882), the PASS (r=−.847) and the BI (r=−.813). The correlation was moderate with the FIM (r=−.693). At six and twelve months, the construct validity of WGS with the FAC, the BBS, the PASS, the BI and the FIM was excellent (r ≥ .8).ConclusionThe WGS has moderate construct validity with walking, balance and functionality scales in patients with acute stroke. The correlation with the FAC, the BBS, the PASS and the BI at subacute and chronic stages was excellent.     

Optimising default radiographic exposure factors using Deviation Index

IntroductionRadiographers have a duty to ensure that radiation doses to patients are as low as reasonably achievable. With digital technologies, exposure factors which achieve the optimum balance between image noise and patient dose must be sought. In digital radiography, Deviation Index (DI) values provide the radiographer with feedback on the appropriateness of individual exposures but can also be tracked as part of a departmental quality assurance programme.MethodsIn November 2017, exposure logs were extracted from six digital radiography (DR) x-ray systems, collated and analysed. Five examinations were identified which frequently produced DI values outside the manufacturer's recommended Optimal Range (-3 to +2). Incremental improvements were made to the default exposure settings for these examinations via a cyclical process of modification and re-evaluation. A full data collection exercise was then repeated in April 2019.ResultsAt baseline, 10,658 out of 29,637 (36.0%) exposures had DI values outside the manufacturer's recommended Optimal Range, but for some individual examinations the proportion was as high as 547 out of 725 (74.5%). Following multiple optimisation cycles, the overall proportion of examinations outside the Optimal Range had fallen to 7611 out of 26,759 (28.4%). Default milliampere-seconds (mAs) values for these examinations were reduced by between 22% and 50%.ConclusionA marked reduction in patient doses can be achieved through a departmental programme of DI value monitoring and targeted optimisation of default exposure settings.Implications for practiceDI values should be routinely monitored as part of routine quality assurance programmes. Radiographers have a responsibility to ensure that they possess a clear understanding of DI values and that appropriate exposure settings are selected for each individual patient.     

Validity and reliability of the Dynamic Gait Index in children with hemiplegic cerebral palsy

BackgroundDynamic Gait Index (DGI) is a performance-based tool can be applied in a short time and evaluates dynamic balance and gait ability.Research questionIs the DGI valid and reliable for assessing gait and balance disorders in children with hemiplegic cerebral palsy (CP)?MethodsSixteen children with hemiplegic CP (5 females, 11 males; mean age 10y 3mo, SD 2y 7mo; range 6–14y; Gross Motor Function Classification System (GMFCS) levels I [n = 9], II [n = 7]) and 16 age-matched typically developing (TD) (8 females, 8 males; mean age 9y 9mo, SD 2y 6mo; range 6–14y) participated. The relationship between the DGI, Four-Square Step Test (FSST), Timed Up and Go Test (TUG) and Pediatric Berg Balance Scale (PBS) was analyzed. To determine the test-retest reliability, the DGI was performed twice and; for the inter-rater reliability, only DGI was reapplied by a different rater on the same day. Internal consistency was obtained by Cronbach-α value. Validity was tested by Spearman correlation coefficient and reliability was calculated by Intraclass correlation coefficient (ICC).ResultsThere was a significant difference between hemiplegic CP and TD and between the children with GMFCS level I and II in the comparison of results of the DGI and other tests. All items on the DGI had appropriate internal consistency (Cronbach-α = 0.969). The test-retest (ICC = 0.970 CI(0.915- 0.990)) and inter-rater (ICC = 0.983 CI(0.882- 0.998)) reliabilities were found to be excellent. A negative, moderate correlation between FSST and DGI (rs = −0.673, p = 0.004); a positive, high correlation between PBS (rs = 0.724, p = 0.002) and DGI and a negative, high correlation between TUG and DGI (rs = −0.828, p < 0.001) was detected.SignificanceDGI with features such as its feasibility in a short time, being simple but distinctive and not requiring heavy equipment is a valid and reliable method in children with hemiplegic CP.     

Reliability and validity of the Edinburgh Visual Gait Score for cerebral palsy when used by inexperienced observers

The Edinburgh Visual Gait Score (EVGS) for cerebral palsy has been validated for observer reliability and validity for observers experienced in gait analysis. This study investigated the reliability and validity of the EVGS for observers inexperienced in gait analysis. Six medical students used the score to analyse videotapes from the original study by Read et al. [Read HS, Hazlewood ME, Hillman SJ, Prescott RJ, Robb JE. Edinburgh visual gait score for use in cerebral palsy. J Pediatr Orthop 2003;23:296-301]. These were viewed on two separate occasions to provide inter- and intra-observer reliability, and the results of the numerical items were compared to those from three-dimensional (3D) gait analyses for validity. Observer agreement was tested using Coefficient of Repeatability (CoR), percentage of complete agreement and the kappa statistic. The CoR for inter-observer agreement for inexperienced observers was 5.99/5.07 (Session 1/Session 2) compared to 4.60/3.95 (Session 1/Session 2) for experienced observers. The CoR for intra-observer agreement for inexperienced observers was 5.15 compared to 4.21 for experienced observers. There was complete agreement for 52% of the 10 numerical items with 3D-gait analysis data for inexperienced observers compared to 64% for experienced observers. Ranking of reliability of individual items was similar between the two groups and was generally best for events occurring at the foot and ankle. Observations of gait events by the inexperienced observers using the EVGS were reasonably reliable but not very accurate when compared to experienced observers and 3D-gait analysis.     

Reliability and validity of the Visual Gait Assessment Scale for children with hemiplegic cerebral palsy when used by experienced and inexperienced observers

This study investigated the reliability and validity of the Visual Gait Assessment Scale when used by experienced and inexperienced observers. Four experienced and six inexperienced observers viewed videotaped footage of four children with hemiplegic cerebral palsy on two separate occasions. Validity of the Scale was obtained by comparison with three-dimensional gait analysis (3DGA). The experienced observers generally had higher inter-observer and intra-observer reliability than the inexperienced observers. Both groups showed higher agreement for assessments made at the ankle and foot than at the knee and hip. The experienced observers had slightly higher agreement with 3DGA than the inexperienced observers. The inexperienced observers showed a learning effect and had higher inter-observer agreement and higher agreement with 3DGA in the second assessment of the videotapes. This scale can be used by inexperienced observers but is limited to observations in the sagittal plane and by poor reliability at the knee and hip for experienced and inexperienced observers.     

The Dynamic Gait Index in healthy older adults: the role of stair climbing, fear of falling and gender

The Dynamic Gait Index (DGI) was developed as a clinical tool to assess gait, balance and fall risk. Because the DGI evaluates not only usual steady-state walking, but also walking during more challenging tasks, it may be an especially sensitive test. The present investigation evaluated the DGI and its association with falls, fear of falling, depression, anxiety and other measures of balance and mobility in 278 healthy elderly individuals. Measures included the DGI, the Berg Balance Test (BBT), the Timed Up and Go (TUAG), the Mini-Mental State Exam (MMSE), the Unified Parkinson's Disease Rating Scale (UPDRS) motor part, the Activities-specific Balance Confidence (ABC) scale and the number of annual falls. The DGI was moderately correlated with the BBT (r=0.53; p<0.001), the TUAG (r=-0.42; p<0.001) and the ABC (r=0.49; p<0.001). Fallers performed worse on the DGI compared to non-fallers (p=0.029). Scores on the DGI were near perfect in men (23.3+/-1.2), but among women, there was a small, but significant (p<0.001) decrease (22.5+/-1.6). The reduction in the DGI score in women was due to stair climbing performance, with many women (65%) choosing to walk while holding a handrail, compared to only 39% of men. Scores on the BBT, the TUAG, the UPDRS and the MMSE were similar in men and women. Conversely, ABC scores and fall history were different. These findings suggest that the DGI, although susceptible to ceiling effects, appears to be an appropriate tool for assessing function in healthy older adults.     

Further evidence against a direct automatic neuromotor link between the ACL and hamstrings.

The purpose of this experiment was to determine whether reflexive, or more broadly, automatic hamstrings excitation could be elicited during isometric, maximum effort, step increases in knee extension torque. Eight healthy subjects without lower extremity dysfunction or injury performed maximum effort isometric knee extension at 15 and 85 degrees of knee flexion in minimum elapsed time. Surface electromyography was used to record medial (semimembranosis and semitendinosis) and lateral (biceps femoris--long head) hamstrings excitation that was subsequently normalized to the excitation during maximum isometric knee flexion. To assess whether automatic hamstrings excitation was elicited, the amplitude of the EMG signals was analyzed and compared for 50 ms prior to peak knee extension torque, and three consecutive 50 ms windows following peak knee extension torque. The amplitude of the EMG subsequent to the peak knee extension torque failed to support the contention of an automatic hamstrings excitation mediated by neural circuitry from the ACL. The present results, in conjunction with previous work, suggest that a protective automatic hamstrings contraction is not normally elicited in response to conditions subjecting the anterior cruciate ligament to strain.     

Intra-rater and inter-rater reliability,minimal detectable change,and construct validity of the Edinburgh Visual Gait Score in children with cerebral palsy

BackgroundThe Edinburgh Visual Gait Score (EVGS) has been used for observational gait assessment in children with cerebral palsy (CP). However, the measurement error of the EVGS and its detailed relationship with gross motor function remain unclear.Research questionsThis study aimed to confirm the intra-rater and inter-rater reliability as well as the minimal detectable change (MDC) values for the EVGS with the use of the video analysis software and examine the relationship between the EVGS and the Gross Motor Function Measure 66 (GMFM-66) with regard to construct validity.MethodsThis cross-sectional study was conducted for 62 children (mean age 11.3 ± 3.9 years) with spastic CP at Gross Motor Function Classification System (GMFCS) level I (32 children), II (25 children) or III (5 children). Three raters independently scored the EVGS using Kinovea video analysis software. The intra-rater and inter-rater reliability were calculated using intra-class correlation coefficients (ICC_2,1), and the MDC₉₀ was calculated using standard error of measurement. The construct validity was examined by correlating the EVGS with the GMFM-66.ResultsThe EVGS showed good or excellent reliability within each rater (ICC_2,1 = 0.90–0.97) and between raters (ICC_2,1 = 0.91). The MDC₉₀ of the EVGS ranged from 3.6 to 6.0. There was a significant correlation between the EVGS and the GMFM-66 (r = − 0.69 to − 0.73, p < 0.001).SignificanceThe intra-rater and inter-rater reliability of the EVGS is sufficient for observational gait assessment. The high correlation between the EVGS and the GMFM-66 supports its construct validity. The authors propose an MDC of 6.0 for the EVGS. These results can help in the application of EVGS to children with CP at GMFCS level I-II with mild to moderate gait pathology, as there were few children with CP at GMFCS level III.     

The Gait Variability Index: A new way to quantify fluctuation magnitude of spatiotemporal parameters during gait

This article describes a conglomerate measure of gait variability based on nine spatiotemporal parameters: the Gait Variability Index (GVI). Concurrent validity, inter-session reliability and minimum detectable change (MDC) were evaluated in 31 patients with Friedreich's Ataxia (FRDA), through comparisons with classically used evaluation tools such as the International Cooperative Ataxia Rating Scale (ICARS).GVI scores for the healthy population were 100.3 ± 8.6 and were significantly reduced in FRDA patients (70.4 ± 7.9). The GVI was correlated with the global ICARS score and was sensitive enough to differentiate between groups of FRDA patients categorized by the Posture and Gait Disturbances sub-score. The GVI was found to have a high inter-session reliability with an intraclass correlation coefficient of 0.91. A MDC of 8.6 points was found necessary to ensure that a change in GVI reflects a true change rather than measurement error.The GVI provides a quantitative measure of variability which behaves well statistically in both HP and patients with FRDA. It can be easily implemented using the supplemental data provided with this article. Complementary work is necessary to strengthen the GVI validation.     

Comparison of the Classifier Oriented Gait Score and the Gait Profile Score based on imitated gait impairments

Common summary measures of gait quality such as the Gait Profile Score (GPS) are based on the principle of measuring a distance from the mean pattern of a healthy reference group in a gait pattern vector space. The recently introduced Classifier Oriented Gait Score (COGS) is a pathology specific score that measures this distance in a unique direction, which is indicated by a linear classifier. This approach has potentially improved the discriminatory power to detect subtle changes in gait patterns but does not incorporate a profile of interpretable sub-scores like the GPS. The main aims of this study were to extend the COGS by decomposing it into interpretable sub-scores as realized in the GPS and to compare the discriminative power of the GPS and COGS. Two types of gait impairments were imitated to enable a high level of control of the gait patterns. Imitated impairments were realized by restricting knee extension and inducing leg length discrepancy. The results showed increased discriminatory power of the COGS for differentiating diverse levels of impairment. Comparison of the GPS and COGS sub-scores and their ability to indicate changes in specific variables supports the validity of both scores. The COGS is an overall measure of gait quality with increased power to detect subtle changes in gait patterns and might be well suited for tracing the effect of a therapeutic treatment over time. The newly introduced sub-scores improved the interpretability of the COGS, which is helpful for practical applications.     

Further evidence for biological effects resulting from ionizing radiation doses in the diagnostic X-ray range

In this study we assessed cell response to ionizing radiation doses in the diagnostic X-ray range, using metabolic performance as the biological end point. HeLa cells were irradiated between 3.5 mGy (standard deviation (SD=2.5%) and 55.1 mGy (SD=0.9%) with 110 kV X-rays, and after 7 days metabolic capacity of cultures was measured spectrophotometrically with resazurin. Cells receiving 7.5 mGy or greater showed impaired proliferation. At 7.5 mGy this effect was prevented by nitric oxide synthase inhibitor N G-monomethyl-L-arginine but not by ascorbic acid or p38 MAPK inhibitor SB203580. We conclude that HeLa cell proliferation is adversely affected by doses within the range of some radiological examinations, through a mechanism involving nitric oxide.