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Effect of sound on standing postural stability in the elderly with and without knee osteoarthritis.

PURPOSE
The aim of the study was to investigate the influence of sound on standing postural control in the elderly with and without knee osteoarthritis (knee-OA).


METHODS
Twenty-six elderly with knee-OA and 26 elderly without knee-OA who matched the age and height participated in this study. The standing postural stability was assessed by the 3D motion analysis system. Four testing conditions of the combination of sound (no sound and white noise sound) and surface (firm and soft surfaces) were tested three times with eyes closed for 30 sec. Postural stability variables included the standard deviation and velocity of the centre of pressure, the total body centre of mass, and centre of the head along the antero-posterior (AP) and medio-lateral (ML) directions.


RESULTS
Statistical significant reductions of all variables along ML direction were found in the elderly without a knee-OA in the presence of sound during standing on a firm surface. No significant effect of sound was found in the elderly with the knee-OA during standing on a firm surface. In the standing on a soft surface, both groups demonstrated no significant effect of sound on all postural stability variables.


CONCLUSIONS
Application of sound improved the standing postural stability in the frontal plane for the elderly without knee-OA. However, the effect of sound was limited in standing on a soft surface for both elderly with and without knee-OA.