Abstract
The Gravity Stress Analyzer (GSA) is a chiropractic instrument designed to measure degrees of rotation and lateral flexion of the head, shoulders and pelvis as these deviate from a perfect alignment in the sagittal plane. In addition, deviations of the 7th cervical and 5th lumbar vertebrae in both the coronal and sagittal planes are recorded. These measures can be carried out by a trained operator in 5 minutes or less. Since the instrument is lightweight, quick to use, and harmless, it would appear to have potential value in research as well as in patient care. To be put to such use, however, it is essential that studies be carried out to determine: (1) the accuracy of measures recorded, and (2) the ranges of measurement that characterize normal, non-patient populations.
Based upon a study of 30 young female students in apparent good health, measurements utilizing the GSA demonstrated (1) that accuracy is best obtained when each subject is measured independently by 3 different operators. This requires more time and operator involvement than has been thought necessary in the past. Thus measured, (2) a normal total score is taken as one that does not exceed one standard deviation above the mean, or 15° of total measured deviations from 90° angles of the compass. This is higher than was previously thought when 5° was given as the stated norm.
Keywords: postural analysis, instrumentation, gravity stress analyzer
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