General Session: Adult Spinal Deformity - Hall F

Presented by: S.Y.G. Fung


G. Liu(1), J.H. Tan(1), S.Y.G. Fung(2), K. Chan(2), H.-K. Wong(1)

(1) National University Health System, Singapore, Singapore
(2) National University of Singapore, Singapore, Singapore


Introduction: Recent advancements in the understanding of sagittal alignment have improved surgical outcomes in patients with adult spinal deformity (ASD). However, sagittal parameters reported in the literature are limited to measurements performed at a specific time point. The aim of this longitudinal study was to analyse the risk factors for progression of sagittal alignment parameters of ASD patients. Methodology: A prospective study of patients with minimum of 2 years follow up was conducted in an university hospital. Clinical and radiological parameters according to SRS-Schwab classification were recorded. SRS24, Oswestery Disability Index (ODI) and visual analogue scale (VAS) scores were captured and analyzed using SPSS software.

Results: 168 patients (142♀ , 26♂ ) with mean age of 66.4 (40-92), menarche of 13.5 (10-19) and menopause of 51.1 (38-67) were reviewed. The average scoliosis Cobb angle was 26.1° (17-70). 70.2% of patients had Nash and Moe grade 2 apical rotation. Mean sacral slope was 25.4° (0-54), mean pelvic tilt (PT) was 24.2° (3-49), and mean pelvic incidence was 55.6° (30-90). 77 (46%) patients had radiological scoliosis progression of ≥5° at 2 years follow up. Mean Cobb progression was 8.0°±3.6 (5-27). Multivariate analysis showed that reversal of lumbar lordosis of ≥0° (OR=7.0, 95%CI:1.8-27, p-value=0.005) is a predictor of scoliosis progression. 16 (10%) patients had ≥5cm sagittal vertical axis (SVA) progression, with mean progression of 66.6mm±19. Multivariate analysis showed that a larger kyphotic thoracolumbar (TL) angle predicts for SVA worsening (OR=0.96, 95%CI:0.93-9.9, p-value=0.005). 56 (33%) patients had ≥5° progression in PT, with an average of 9.25°±7.80. Univariate analysis showed increasing TL, abnormal global alignment, and increased T1-pelvic angle predicted for PT progression. 91% of patients improved more than the established minimum clinically important difference in VAS, and 83% of patients improved more than the MCID in ODI. The spearman correlation with radiological progression was poor (r=0.23). 6 (4%) patients in the study had intractable radicular leg pain, and underwent deformity correction surgery.

Conclusion: To the best of the author knowledge, few papers have demonstrated the natural history and predictors for progression of ASD. The reversal of LL is a predictor for Cobb progression, and a kyphotic TL with poor global alignment and increased T1-sagittal angle predicts sagittal parameters deterioration. Despite radiological deterioration, >80% of patients improve with conservative treatment with good clinical outcome scores.