# Restoration of Sagittal Alignment as a Key Factor in Degenerative Spine Surgery: A Comparative Analysis of Outcomes in Postoperative Balanced and Imbalanced Cases

## TL;DR

This study compares outcomes of spine surgery in patients with and without corrected sagittal alignment, finding similar improvements in quality of life.

## Contribution

The study shows that limited fusion can yield good results even without perfect sagittal balance in patients with leg symptoms.

## Key findings

- Both balanced and imbalanced groups showed significant improvement in quality-of-life scores after surgery.
- No significant difference in improvement was found between the balanced and imbalanced groups.
- A weak negative correlation was found between VAS score change and socioeconomic status in imbalanced patients.

## Abstract

Introduction

The current consensus for treating sagittal imbalance in degenerative spine disease supports deformity correction. However, there is a growing trend toward limited fusion, particularly in patients presenting predominantly with leg symptoms. The present study aimed to compare radiological and clinical outcomes following lumbar fusion between patients with postoperative sagittal balance and those with residual imbalance.

Methods

This study included 270 patients who underwent limited lumbar arthrodesis and were followed for two years. Radiological parameters-sagittal vertical axis (SVA), pelvic incidence (PI), pelvic tilt (PT), and sacral slope (SS)-were recorded preoperatively and at the final follow-up. Clinical outcomes were assessed using the Oswestry Disability Index (ODI), Visual Analogue Scale (VAS), and Short Form-36 (SF-36). Patients were divided into two groups based on postoperative sagittal alignment: balanced (SVA < 50 mm) and imbalanced (SVA > 50 mm). Both intragroup pre- and postoperative improvements and intergroup differences in outcomes were analyzed.

Results

Out of 270 patients, 194 had good sagittal alignment and 76 had sagittal imbalance (SVA > 50 mm). Both groups showed significant postoperative (two-year follow-up) improvement in quality-of-life scores (VAS, ODI, and SF-36) compared with baseline values (p < 0.001). However, when comparing the degree of improvement between the balanced and imbalanced groups, no statistically significant differences were observed. A significant but weak negative correlation was noted between the change in the VAS score and the socioeconomic status in patients with sagittal imbalance of the spine.

Conclusion

In appropriately selected patients, limited lumbar fusion can achieve favorable short-term outcomes irrespective of postoperative sagittal alignment. These findings suggest that extensive deformity correction may not always be necessary in degenerative cases presenting primarily with leg symptoms.