about the validity and reliability of the various applications of posturographic measurements have been raised consistently over the years. The approaches and analysis techniques that exist for posturography vary widely [28] and further complicate attempts to find agreement within the literature. There is little consensus regarding the best approaches for assessment or interpretation [26]. Recent publications have also identified an assortment of factors that may significantly impact findings based on posturographic testing, including the instructions given to the patient prior to testing [29], the patient’s stance [30], stability of the platform for CDP [31], the type of balance pad used [32], and the time of day the testing takes place [33]. While most of these factors are likely to stay reasonably stable across time for an individual patient, or even for all patients within a given center, these findings emphasize that even subtle factors may further hamper our ability to make comparisons between studies.
Posturography has not yet been shown to be effective as a diagnostic tool for any disorder, including disorders of balance; the results are non-localizing and there is significant overlap between the results of patients with normal and abnormal vestibular functions [34, 35]. Of the investigations that have looked at posturography for diagnosis, most are retrospective and do not include calculations of sensitivity and specificity [27]. Work is needed to better separate abnormal populations from normal controls if posturography is to be used for diagnostic purposes in the future.
A search of the Pubmed database using the term “posturography” reveals that mentions of posturography have tripled in the past 5 years compared with the previous 5 years. While caution is required when determining the dependence on posturographic results until there is more agreement within the literature, there is hope that continued research efforts will answer some important questions related to posturography and will lead to the standardization of approaches and analysis techniques.
Technological Innovations
The most apparent recent advance within the realm of posturography has been the drive to validate lower cost alternatives to traditional force-plate systems. In particular, the Nintendo Wii Balance Board (WBB), an accessory for the Wii video game console that contains pressure sensors, has inspired a surge in publications looking at the validity of the system for quantifying posturography, so far the results are very encouraging [36–38]. However, other researchers have expressed concern that the WBB may not be an appropriate alternative to traditional force-plates in some instances [39–41].
Currently, the most promising application of the WBB appears to be balance training; the low-cost and portability of the system makes it suitable for at-home use. Balance training studies with the WBB have already shown significant improvements in functional balance in normal participants [42], as well as in elderly patients [43], and patients with multiple sclerosis [44]. The majority of research in this area so far has focused on the games available for the Wii platform, the Wii Fit suite being the most prominent. However, it is also possible to use the Wii platform with custom software, an option that may further improve the outcomes from balance training [43]. Researchers have also begun to explore the use of virtual reality to enhance what can be done with traditional posturography, particularly within the area of balance training. Early publications for different patient groups (e.g., multiple sclerosis [45], vestibular impairment [46], elderly [47]) show promise and correlate well with the sensory organization task [48].
Though postural sway is most commonly measured using force plates that record center of pressure, other techniques have also been proposed. Accelerometry uses inertial sensors, which can be embedded in body worn devices when portability is of primary importance [49] and for mobile posturographic measurements [50]. Research on accelerometry has shown good correlation with force plate measures [49, 51], high test-retest reliability [49], and sensitivity for detecting changes in balance [51]. While this approach is not new, the technology is becoming increasingly accessible, since most smartphones come equipped with accelerometers and gyroscopes of sufficient sensitivity. Investigators have already begun to establish the accuracy of smartphone and tablet-based accelerometers and gyroscopes for measuring postural control in normal patients [52] and in patient groups associated with abnormal postural sway [53].
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