COMPARISON OF STANDING SAGITTAL SPINAL ALIGNMENT IN ASYMPTOMATIC ADOLESCENTS AND ADULTS

Study Design. A retrospective examination of the spine radiographs of 88 asymptomatic adolescents was performed to analyze the indices of re gional and segmental sagittal spinal alignment in relation to the sagi ttal vertical axis as determined by the C7 plumb line. Objectives. To determine the sagittal spinal alignment in asymptomatic adolescents an d to correlate the sagittal vertical axis with the overall sagittal sp inal balance and other indices of sagittal spinal alignment, In additi on, to compare these results with previously established data for asym ptomatic adults, Summary of Background Data. Previous studies of sagit tal spinal alignment have included subjects encompassing a wide range of ages. A previous study at the authors' institution established norm ative data for sagital spinal alignment in asymptomatic adults. No pre vious study has reported on the correlation between the sagittal verti cal axis and other measurements of sagittal spinal alignment in asympt omatic adolescents. Methods. Measurements obtained from the standing l ateral spine radiographs of 88 asymptomatic adolescents (age range, 10 -18 years) were collected and ana lyzed using statistical methods. The se data were compared with previously established data for asymptomati c adults, Results. There was a striking similarity in regional thoraci c kyphosis and lumbar lordosis between adolescents and adults. Despite having similar regional and segmental sagittal alignments, adolescent s had a significantly more negative sagittal vertical axis (mean, -5.6 cm) than adults (mean, -3.2 cm; P = 0.0001). Also, unlike that in adu lts, the sagittal vertical axis in adolescents was not significantly c orrelated with the distal segmental lumbar lordosis. The sagittal vert ical axis in adolescents was significantly correlated with the level o f thoracic kyphosis and the distances from the thoracic apex, lumbar a pex, and T12 to the C7 plumb line. Sacral inclination, which is a dete rminant of hip extension and standing pelvic rotation, was correlated with the lumbar apex and the total and segmental lordosis, except at L 5-S1. Conclusions, Asymptomatic adolescents tend to stand in greater n egative sagittal spinal balance than asymptomatic adults, despite simi lar regional and segmental alignments in the thoracic and lumbar spine . The role of hip extension, spinopelvic axis rotation, and other sagi ttal alignment parameters in determining the sagittal vertical axis in adolescents warrants further study.