Asymmetry vs Deviation plot (ADplot) is a data reduction and enhanced analysis tool, developed for Gait Analysis.
Gait Graph Asymmetry has been defined as the difference observed between the left and the right side gait analysis graph curves of the subject measured.
Gait Graph Deviation has been defined as the difference observed between the left side gait analysis graph curve of the subject measured with the mean curve of the normal subjects group that are used as controls, as well as the right side gait analysis graph curve with the mean normal subjects curve.
Asymmetry vs Deviation plot is a gait analysis instrument that helps to summarize and visualize the Asymmetry and Deviation observed in gait analysis graphs simultaneously.
A sort reference about the history of the development of the ADplot is presented here
For the construction of the ADplot, Asymmetry and Deviation observed in a gait analysis graph are expressed as proportion to the Standard Deviation (SDs) that the normal subject group exhibit in the respective gait graph. So, these values express how many Normal Standard Deviations are needed to produce the differences observed in Asymmetry and Deviation.
These values are clinically relevant, because they allow the direct evaluation of the severity of the deviation. In gait analysis, deviations observed for the subject measured within one Standard Deviation of the normal subjects group, are considered non pathological or within the normal range, while larger deviations are considered increasingly pathological.
Gait Graph Asymmetry Indexes (GGAI) and Right & Left Gait Graph Deviation Indexes (GGDI) summarize the Asymmetry and Deviation observed in gait graph in just three numbers. These three values are used to construct various types of ADplots. ADplots help to visualize the characteristics of the graphs for the subjects measured for these two very important parameters of pathology.
ADplot construction.
There are three main stages for the construction of the ADplot. Detailed description of the steps to follow within each stage are documented in the following links:
Stage 1. Calculate the Gait Graph Deviation Index -> GGDItot or GGDI
Stage 2. Calculate Gait Graph Asymmetry Index -> GGAItot or GGAI
Stege 3. Construct the Asymmetry vs Deviation Plot -> ADplot
What is it for?
ADplot has great versatility and may be used for various applications.
Clinical gait analysis can be enhanced by evaluating subject's gait using the classical gait graphs together with the Gait TriPlane ADplots and the Gait PrePlaneADplots
Overall evaluation of the measurements Pre-Post treatment of a patient using the respective Pre-Post Gait Global ADplot can be
ADplot is a data reduction tool to produce comprehensive and accurate results for evaluating subject's consistency over multiple gait cycles using the Gait Consistency ADplot.
Another ADplot version is particularly suitable for comparing different data sets. Group Analysis ADplot is a highly informative graph that helps to visualize the behavior differences in asymmetry and deviation of the groups.
Ultimately the Unified Summary ADplot version can be used to create maps of gait graph pathology.
Unified Summary ADplot can be used to locate the mean Asymmetry and Deviation values for a specific group of patients. Then the SD bars around the mean values are used as the lower and upper limits of the ranges that define the moderate gait graph pathology area. By mapping the moderate gait graph pathology area of the specified group of patients , it is then possible to discriminate whether the measured subject's values are showing light, moderate or heavy pathology.