Impact of Global Sagittal Spinal Alignment on Degenerative Lumbar Scoliosis

In spine surgery, understanding the balance between sagittal and coronal planes, taking both spinal alignment and pelvic orientation into account, is crucial. The purpose of this study was to clarify the influence of pelvic incidence (PI) on spinopelvic parameters in patients with degenerative lumbar scoliosis (DLS) by comparing them to those without DLS.

The subjects were 259 patients (146 men and 113 women, mean age 69.4 years) who underwent surgery in our department between January 2010 and August 2018. The nonscoliosis group (N group, Cobb angle: 0°-9°; n = 161) and the scoliosis group (S group, Cobb angle: 10°-29°; n = 98) were used to compare their spinal alignments.

Regarding the parameters of sagittal spinal alignment, lumbar lordosis (LL) (N group 35.3 ± 12.5°; S group 31.6 ± 14.9°) was significantly smaller (p < 0.05) and PI (N group 46.6 ± 11.6°; S group 52.3 ± 12.1°) and PI-LL (N group 11.8 ± 14.3°; S group 21.0 ± 17.5°) were significantly larger (p < 0.001) in the S group than in the N group. Positive correlations were observed between Cobb angle and sagittal vertical axis (SVA), pelvic tilt (PT), PI, and PI-LL, and a negative correlation was observed between Cobb angle and LL.

The incidence of DLS in middle-aged and older patients is related to PI, and the coronal Cobb angle is positively correlated with PI and PI-LL and is negatively correlated with LL. Coronal deformity could be affected by both pelvic orientation and sagittal spine alignment.