Fixed coronal malalignment (CM) in the lumbar spine independently impacts disability in adult spinal deformity (ASD) patients when considering the obeid-CM (O-CM) classification

The correction range of lumbosacral curve vertebral body tilt in degenerative scoliosis for achieving postoperative coronal balance

PURPOSE

To explore the relationship between lumbosacral curve vertebral body tilt correction and postoperative coronal balance in adult degenerative scoliosis to determine the ideal target values for the tilt correction.

METHODS

We conducted a retrospective analysis of 144 patients who underwent surgery between January 2017 and December 2023. Patients were classified based on the preoperative Obeid classification and fixation segment length into Concave Long Segment (Concave-L, n = 41), Concave Short Segment (Concave-S, n = 33), Convex Long Segment (Convex-L, n = 39), and Convex Short Segment (Convex-S, n = 31). Changes in coronal and sagittal radiographic parameters and the correlation between the correction percentage of the most tilted vertebra (L4 or L5) and postoperative coronal balance distance (CBD) were assessed.

RESULTS

Significant postoperative improvements in CBD, maximum coronal tilt, and Cobb angle were observed in the Concave-L, Convex-L, and Convex-S groups. The Concave-S group exhibited significant changes only in Cobb angle and maximum coronal tilt, but not CBD. A significant negative correlation existed between postoperative CBD and the correction ratio of maximum coronal tilt in the convex malalignment (r=-0.629, P < 0.001), with the regression equation: Postoperative CBD = 32.99 - (28.82 × Correction Ratio of Coronal Tilt). A correction ratio exceeding 45% at L4 or L5 tilt predicted a postoperative CBD within 20 mm.

CONCLUSION

Both short and long segment fusions effectively correct convex coronal malalignment, but concave malalignment requires long segment fusion for adequate correction. Optimal coronal balance in convex malalignment is achieved when the maximum tilt correction ratio exceeds 45%.

Impact of postoperative spinal malalignment on postoperative health-related quality of life after long-level fixation for degenerative lumbar scoliosis: does residual coronal angularity matter?

PURPOSE

This study evaluates the influence of spinal malalignment on health-related quality of life (HRQOL) in a long-level fusion spine.

METHODS

This was a retrospective analysis of 121 consecutive patients with DLS after long-segment fusion. HRQOL and radiographic parameters were collected at final follow-up. For postoperative residual Cobb angle (CA), patients were divided as follows: group (0) (CA < 10°), group (+) (CA 10°∼20 °), and group (++) (CA > 20°). For postoperative coronal vertical axis (CVA), patients were separated as follows: group (0) (CVA < 2 cm), group (+) (CVA 2 ∼ 3 cm), and group (++) (CVA > 3 cm). Patients were also grouped by the sagittal modifiers as group (0), group (+), and group (++) according to the Scoliosis Research Society (SRS)-Schwab classification, respectively.

RESULTS

Visual analog scale (VAS) for back was significantly lower in CA 10°∼20° group compared to other groups. Patients with remnant CA > 20° showed worse Oswestry Disability Index (ODI), SRS-22 and the 36-item Short Form Health Survey (SF-36) - physical component scores (PCS). Sagittal vertical axis (SVA) showed significant correlation with HRQOLs after surgery, and the statistical significance of ODI, SRS-22 and SF-36 scores was observed among subgroups.

CONCLUSIONS

In long-level fused spine, residual CA > 20° resulted in worse clinical outcomes and was recommended to avoid during surgery. And 10° to 20° residual CA was acceptable in DLS patients and even better than Cobb angle < 10° in several HRQOLs, therefore strictly pursing upright alignment seems unnecessary. SVA also showed effectiveness in assessing HRQOL in the fixed spine.

Coronal Alignment in Adult Spine Surgery

Coronal realignment is an important goal in adult spine surgery that has been overshadowed by emphasis on the sagittal plane. As coronal malalignment drives considerable functional disability, a fundamental understanding of its clinical and radiographic evaluation and surgical techniques to prevent its development is of utmost importance. In this study, we review etiologies of coronal malalignment and their radiographic and clinical assessments, risk factors for and functional implications of postoperative coronal malalignment, and surgical strategies to optimize appropriate coronal realignment in adult spine surgery.