Correlation analysis of global sagittal alignment of the spine in cases of low-grade degenerative lumbar spondylolisthesis

Purpose: Disruptions in global sagittal spinal alignment can lead to changes in global sagittal spinal alignment, often manifesting as sagittal malalignment, where the trunk shifts forward. We proposed that these alignment changes are linked to degenerative lumbar spondylolisthesis (DS). The objective was to assess global spinal alignment in low-grade DS using sagittal vertical axis (SVA) classification.

Methods: The patients with DS were categorized into three groups based on the adult spinal deformity classification: type I, defined by a SVA of less than 40 mm; type II, with an SVA ranging from 40 mm to 95 mm; and type III, where the SVA is 95 mm or greater. The study compared age and various sagittal parameters among these groups, including thoracic kyphosis (TK), lumbar lordosis (LL), sacral slope (SS), pelvic tilt (PT), and pelvic incidence (PI).

Results: Notable differences were observed between type I and type II, as well as between type I and type III, whereas no substantial variation was detected between type II and type III. Additionally, PI increased with advancing type classification, with a distinct contrast observed between type I and type III.

Conclusion: A high PI is a key risk factor for worsening SVA in DS, and it may contribute to the initiation and progression of the condition.