Relationship between Preoperative Global Sagittal Alignment and Changes in Cervical Alignment Following Lumbar...

Area of Science:

• Spine surgery
• Orthopedics
• Surgical outcomes

Background:

• Cervical alignment changes after lumbar pedicle subtraction osteotomy (PSO) are known but poorly understood.
• Predictors of long-term cervical decompensation after PSO remain unclear.

Purpose of the Study:

• To assess cervical sagittal alignment changes following lumbar PSO.
• To examine the association between preoperative global sagittal alignment (GSA) and these cervical changes.

Main Methods:

• Retrospective cohort study of 99 patients undergoing lumbar PSO (2016-2021).
• Cervical alignment was measured preoperatively and at five postoperative time points up to 2 years.
• Key parameters included cervical lordosis, C2-7 sagittal vertical axis (cSVA), T1 slope, and global sagittal alignment (GSA) metrics like pelvic tilt (PT) and pelvic incidence-lumbar lordosis mismatch (PI-LL).

Main Results:

• Immediate postoperative changes showed reductions in cSVA, cervical lordosis, and T1 slope.
• Longer-term analysis revealed progressive increases in cSVA, T1 slope, and cranial slope.
• Higher preoperative sagittal vertical axis (SVA) correlated with immediate cervical adaptation, while higher PT was linked to long-term compensatory changes.

Conclusions:

• Preoperative GSA parameters influence cervical alignment in a phase-specific manner after lumbar PSO.
• Higher preoperative SVA is associated with immediate cervical adaptation.
• Pelvic parameters are more strongly related to long-term cervical compensatory responses.