The repeatablity of spinal motion of normal and scoliotic adolescents during walking.

The main aim of this study was to assess the within-day repeatability of measuring trunk and spinal motion during walking using external markers and a motion analysis system. A secondary aim was to compare the repeatability of motion between the scoliotic and normal spine. The sagittal and coronal plane trunk and spinal motion, three-dimensional pelvic and shoulder motion of 9 normal and 19 scoliotic adolescents was assessed. Intra-subject within-day repeatability was evaluated using waveform similarity statistics. Trunk sagittal and coronal plane motion was fairly repeatable. Repeatability of spinal frontal plane motion was fair, but that of sagittal plane motion is poor. Pelvic coronal and transverse plane motion was very reproducible but pelvic sagittal plane motion was very variable. Shoulder motion in all three planes was found to have a poor level of repeatability. A relationship possibly exists between the range of motion and repeatability values. Although the scoliotic adolescents had less variable spinal motion, differences from the normal subjects were not statistically significant. However, the scoliotic subjects had significantly more repeatable sagittal and coronal plane pelvic motion and coronal plane shoulder motion. The results of this study suggest that trunk sagittal and coronal plane motion and spinal coronal plane motion of normal and scoliotic adolescents can be reliably measured within a single test session.