Clinical multisegmental posturography: age-related changes in stance control

Unlike conventional platform posturography, which analyses the sway in the projection of the body baricentre on a supporting plane, multisegmental posturography provides information about body segmental movements during stance, including those that keep the baricentre still. This paper presents a new technical approach to multisegmental posturography using Virtual Reality electromagnetic tracking devices. This device was used to study age-related differences in normal subjects in the control of upright posture. Body sway was studied by recording the oscillations of two trackers placed on the head and the hip during the Romberg test. The tracking device allowed us to detect age-related differences in postural stance strategies. Although the amplitude and velocity of the oscillations measured at the head did not differ in the two groups, the flexibility of the ankle-hip head axis differed significantly: elderly subjects exhibited a more rigid stance. Closing the eyes increased rigidity in both age groups and this change appear more pronounced in the young.