Gait Deviation Graphs

In the classical gait graphs, it is not always easy to quantify the distances of the right and left gait curves from the normal gait curve.

For this reason the Gait Deviation Graphs were developed.

These graphs are showing the deviation/distance from normal subjects mean values at each moment of the gait cycle.

Create Gait Deviation Graphs

Subtract Right Side from Normal Mean

Subtract Left Side from Normal Mean

Figure 1. Transition from the classical Gait Graph to Gait Deviation Graphs

For the construction of the Gait Deviation Graph:

On the x-axis, time is expressed as percentage of the gait cycle.

On the y-axis, numerical values for the Right and Left side curves derived from the subtraction of the measured subjects’ Y values from the respective mean Normal Subjects Y values at each moment of the gait cycle.

These values were defined as: Instant Gait Graph Deviation in Y axis IGGDy(t)

Right IGGDy(t) = Right y(t)- Normal y(t)

Left IGGDy(t) = Left y(t)- Normal y(t)

t=1 to 100% of the gait cycle

A final step for plotting these graphs is to draw a green area around the x-axis zero value.

This green area around x-axis zero value, is exactly the same as the green area drawn around the Normal subjects mean value in the classical gait graphs. This area represents the range of one Standard Deviation of the Normal subjects at each instant of the gait cycle. Thus if all subject's IGGDy(t) values are included within this green area they are considered within normal range. If IGGDy(t) values exceed this green area then these values are out of normal range.

Finally it is recommended to use in all the Gait Deviation Graphs the same axis limits (i.e. min -50 and max 50 degrees) . This enables the observer to view in the same scale the variability of the standard deviations as well as the changes of the instant gait graph deviations among the graphs. In the classical gait graphs this is not possible because, in order to incorporate the motion curve in the graph different scaling values are used in each graph.

Gait Deviation Graphs are assisting the quantification of changes of deviation throughout the gait cycle and also visualizing a direct comparison of deviation development of the left and right curves.

Figure 2. Classical Gait Report Graphs and the respective Gait Deviation Graphs.