Posturography

Static posturography is carried out by placing the patient in a standing posture on a fixed instrumented platform (forceplate) connected to sensitive detectors (force and movement transducers), which are able to detect the tiny oscillations of the body.

The computer is also used to command electric motors which can move the forceplate in the horizontal direction (translation) as well as to incline it (rotations).

A special computer software integrates all this and produces detailed graphics and reports which can then be compared with normal ranges.

COP excursion and velocity are indicators of control over COG and are key factors for identifying proper posture and the ability to maintain balance.

COP excursion is defined by Collins & De Luca (1992) as the Euclidean*LINK* displacement in the anterior/posterior and medial/lateral directions within the base of support (perimeter around the feet).

[4] The SOT test is based on the fact that there are three sensory systems mainly involved in maintaining balance (vision, vestibular, and proprioceptive).

[5][6] Minute spontaneous body sways are measured as well as reactions provoked by unexpected abrupt movements of the platform and the visual surroundings.

Differences in these sways and reactions to system perturbations help to determine the patients ability to effectively use visual, vestibular, and proprioceptive input to maintain posture.

[7] Wrisley et al. (2007) found that there are learning effects associated with the SOT test and therefore it could be used clinically to assess, improve and track changes in balance.

The limits of stability (LOS) is defined as the distance outside the base of support that can be traveled before a loss of balance occurs.

The LOS test is frequently used to quantify this distance and has been suggested as a hybrid between static and dynamic balance assessment.