Variability in three-dimensional measurements of back contour with raster stereography in normal subjects

Forty normal children with a mean age of 9.1 years were investigated by usi ng a Quantec Spinal Image System (QSIS). The QSIS uses computerized raster stereography technology to acquire three-dimensional measurements of back c ontour. Within a 95-percentile confidence interval (a) coronal-plane QSIS a ngles ranged from 0.05 to 2.36 degrees; (b) transverse-plane QSIS angles ra nged from 0.03 to 1.96 degrees; and (c) sagittal-plane QSIS angles ranged f rom 36.8 to 44.8 degrees. Trunk-alignment deviation ranged from 3.51 to 7.4 5 mm within a 95-percentile confidence interval. An intraobserver standard deviation of +/-4.2 degrees was noted across all angular metrics. Normal ra nges of QSIS-determined values for a population of 40 children without clin ical evidence of pathology are reported.