Relationships between lumbar lordosis correction and the change in global tilt (GT) in adult spinal deformity

Purpose This study aimed to explore the relationships between lumbar lordosis (LL) correction and improvement of postoperative global sagittal alignment and to establish corresponding linear regressions to predict the change in global tilt (GT) based on the corrected LL following adult spinal deformity (ASD) surgery. Methods A total of 240 ASD patients who underwent lumbar correction were enrolled in this multicentre study. The following sagittal parameters were measured pre- and postoperatively: thoracic kyphosis (TK), LL, upper and lower LL (ULL and LLL), pelvic tilt (PT), sagittal vertical axis (SVA) and GT. The correlations among the changes in GT (△GT), SVA (△SVA), PT (△PT), TK (△TK), LL (△LL), ULL (△ULL) and LLL (△LLL) were assessed, and linear regressions were conducted to predict △GT, △SVA, △PT and △TK from △LL, △ULL and △LLL. Results △LL was statistically correlated with △GT (r = 0.798, P < 0.001), △SVA ( r = 0.678, P < 0.001), △PT ( r = 0.662, P < 0.001) and △TK ( r = − 0.545, P < 0.001), and the outcomes of the linear regressions are: △GT = 3.18 + 0.69 × △LL ( R 2 = 0.636), △SVA = 4.78 + 2.57 × △LL ( R 2 = 0.459), △PT = 2.57 + 0.34 × △LL ( R 2 = 0.439), △TK = 7.06–0.43 × △LL ( R 2 = 0.297). In addition, △LLL had more correlations with △GT, △SVA and △PT, while △ULL had more correlations with △TK. Conclusion Surgical correction of LL could contribute to the restoration of global sagittal morphology following ASD surgery. These models were established to predict the changes in sagittal parameters, in particular △GT, determined by △LL, which has not been previously done and may help to customize a more precise correction plan for ASD patients.