Differences in standing and sitting spinopelvic sagittal alignment for patients with posterior lumbar fusion: important considerations for the changes of unfused adjacent segments lordosis.

The most noticeable changes in spinopelvic sagittal alignment occurred in the natural sitting position after lumbar fusion. Age, fusion levels, and lumbosacral fusion significantly influenced the differences in LL and URL between the standing and natural sitting position. These characteristics should be fully considered when planning spinal realignment surgery and investigating the etiological factors of junctional complications.