Background: Although a leg length inequality (LLI) has the effect on the performed movement, more complex indices for the evaluation of kinematic variables of postural stability and a symmetry of a muscle activity during standing in subjects with the LLI were never used before.
Objective: The objective is to present appropriate parameters for an evaluation of kinematic variables of postural stability and muscle activity during standing, i.e. to consider EMG signals, in patients with LLI.
Methods: New indices are offered, such as a sway velocity (i.e. the mCTSIB method) and a modified symmetry index (SI), for a quantitative evaluation of EMG signals. The set of data for evaluating the effect of a heel lift was measured on patients with the LLI and healthy volunteers.
Results: Prior to the heel lift application, significant statistic differences were found between the mCTSIB of patients and the CG. These differences were no longer statistically significant after the heel lift was applied. As for the SI, the lowest values were found in the CG, while the greatest values were collected among patients before applying the heel lift.
Conclusions: The results point out the benefits of using the newly applied indices in patients with the LLI. Both methods may become useful tools for the evaluation of the physical state of patients with the LLI in a medical practice.
Keywords: Leg length inequality; heel lift; postural stability during standing; symmetry of muscle activity.