Postural Symmetry Evaluation Based on the Analysis of Temporary and Average CoP Displacements Registered During the Follow-Up Posturography

Abstract

This paper presents a method enabling a postural symmetry assessment based on the evaluation of similarity of temporary and average CoP (Center of Pressure) displacements registered in response to the clockwise and counterclockwise visual stimuli applied while performing the so-called follow-up posturography. This kind of visual feedback diagnostics is an intermediary between the static posturography and the dynamic posturography. One of its advantages is the ability to evaluate the dynamic performance of the human balance and posture control mechanisms using relatively inexpensive and popular static posturography platforms. The method presented in this paper was developed as a means for measuring the effectiveness of the rehabilitation program following total hip arthroplasty. The postural symmetry is, in this case, evaluated as the degree of mutual symmetry of the visually stimulated loading exerted on the left and right lower limbs. Usability of the method was verified in the group of 30 patients rehabilitated after total hip arthroplasty. The statistical analysis confirmed a significant growth of the values of the proposed symmetry measure over the period of the 21-day rehabilitation program (p < 0.001). There were, however, no significant correlations between that measure and the symmetry measures applied in the case of static posturography. The obtained results support the statement that the herein presented diagnostic approach enables the quantification of some other aspects of postural symmetry, namely the dynamic ones. This also corroborates the diagnostic value of the method discussed in this paper. INDEX TERMS postural symmetry evaluation, posturography, the follow-up posturography, biomedical signal processing, total hip arthroplasty.