THE RELIABILITY OF POSTURAL SWAY MEASURES USING THE 3SPACE TRACKER

Objective. To investigate the reliability of three-dimensional postura l control sway measures, in a normal population, using an electromagne tic device. Design. A repeated measures design was used within and bet ween sessions. Background. Electromagnetic measurement has been propos ed as a method of measuring postural sway; however, reliability within a normal population has not been shown. Method. An electromagnetic de vice, the 3SPACE Tracker, measured postural sway at the pelvis using s way path length and displacements in the anterior-posterior, medial-la teral and vertical direction. Ten subjects performed a postural contro l task involving two trials for six different sensory conditions, on t wo separate occasions, two weeks apart. Results. The reliability of th e technique was demonstrated by the repeatability of results for indiv idual subjects within and between sessions. Individual subjects and se nsory conditions were discriminated. Sway path length was the most con sistent of the measures used. Conclusions. Three dimensional measures of postural sway are reliable and discriminatory in a normal populatio n.