The Standing and Sitting Spino-Pelvic Sagittal Alignment in Patients with Instrumented Lumbar Fusion Might Correlate with Adjacent Segment Degeneration.

The spine straightens in lumbar and thoracic curve, combined with forward-moving axis and pelvic retroversion when changing to the sitting position. However, these changes are relatively limited in patients after lumbar fusion, so the adjacent unfused lumbar segments compensate to stress during sitting and this may be related to ASD.