Gait Asymmetry Graphs

In the classical gait graphs, it is not easy to quantify the distance between the right and left gait curves of the subject measured. For this reason the Gait Asymmetry Graphs were developed.

These graphs are showing the distance between the subject's right and left gait analysis curves at each moment of the gait cycle.

Create the Gait Asymmetry Graphs

Subtract Left Side from Right Side

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

For the construction of the Gait Asymmetry Graph:

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

On the y-axis, numerical values derived from the subtraction of the measured Left side subject’s Y values from the respective Right side subject’s Y values at each moment of the gait cycle are plotted.

Instant Gait Graph Asymmetry IGGAy(t)= Right y(t)- Left 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 green area represents the range of one Standard Deviation of the Normal subjects at each instant of the gait cycle. Thus if all subject's IGGAy(t) values are included within this green area they are considered within normal asymmetry range. If IGGAy(t) values exceed this gray area then these values are out of normal asymmetry range.

The concept behind using the same green area for Asymmetry with the one we are using for the Deviation graphs is based on the following facts:

• Normal curves have been created by including both sides (left &* right) so the inherent asymmetry of the normal subjects is incorporated in the Normal subjects Standard Deviation

• In clinical practice, if one of the limb curves follows exactly the Normal mean values ad the other curve would follow the borders of the Normal SD range, this would not be considered a pathological behavior.

Gait Asymmetry Graphs are assisting the quantification of changes of asymmetry throughout the gait cycle.

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