The gait profile score and movement analysis profile.
ABSTRACT The Gait Deviation Index (GDI) has been proposed as an index of overall gait pathology. This study proposes an interpretation of the difference measure upon which the GDI is based, which naturally leads to the definition of a similar index, the Gait Profile Score (GPS). The GPS can be calculated independently of the feature analysis upon which the GDI is based. Understanding what the underlying difference measure represents also suggests that reporting a raw score, as the GPS does, may have advantages over the logarithmic transformation and z-scaling incorporated in the GDI. It also leads to the concept of a Movement Analysis Profile (MAP) to summarise much of the information contained within kinematic data. A validation study on all children attending a paediatric gait analysis service over 3 years (407 children) provides evidence to support the use of the GPS through analysis of its frequency distribution across different Gross Motor Function Classification System (GMFCS) and Gillette Functional Assessment Questionnaire (FAQ) categories, investigation of intra-session variability, and correlation with the square root of GGI. Correlation with GDI confirms the strong relationship between the two measures. The study concludes that GDI and GPS are alternative and closely related measures. The GDI has prior art and is particularly useful in applications arising out of feature analysis such as cluster analysis or subject matching. The GPS will be easier to calculate for new models where a large reference dataset is not available and in association with applications using the MAP.
- SourceAvailable from: Michael H Schwartz[show abstract] [hide abstract]
ABSTRACT: 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.Gait & Posture 07/2008; 28(3):351-7. · 1.97 Impact Factor
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ABSTRACT: 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 & Posture 05/2008; 28(3):483-7. · 1.97 Impact Factor
- Gait & Posture - GAIT POSTURE. 01/2008; 28.