Sagittal Alignment in Operative Degenerative Lumbar Spondylolisthesis

This scoping review synthesizes evidence on radiographic alignment assessment in degenerative lumbar spondylolisthesis (DLS) surgery, analyzing 109 studies (10,730 patients, average age 63) published from 1971–2023. It highlights a surge in research over the last decade (85% of studies), though predominantly retrospective (64%) or case series (20%) with low evidence levels (68% level III/IV).

Key Findings

Radiographic Focus: Most studies (84%) evaluated postoperative alignment changes, primarily at the index DLS level or lumbar spine. Only 34% assessed spinopelvic parameters, and 12% used 36-inch standing radiographs for global alignment.

• Surgical Comparisons: Common comparisons included PLIF/TLIF vs. PLIF/TLIF (47% of comparative studies) and PLIF/TLIF vs. posterolateral fusion (21%).

• Alignment-Outcome Links: Conflicting evidence exists on sagittal alignment’s impact (e.g., PI-LL mismatch, SVA >5 cm correlating with worse outcomes), with heterogeneity limiting definitive conclusions.

Critical Gaps

• Standardization: Inconsistent radiographic protocols and underreporting of global alignment (e.g., pelvic tilt, T1 pelvic angle) hinder comparative analysis.

• Evidence Quality: Small cohorts and retrospective designs dominate, exaggerating effect sizes and obscuring alignment’s true role in functional outcomes.