Xueneng Yang, Ruijuan Li, Junfei Liu, Bo Li, Jun Shu
Supine CT-measured AVR is associated with clinical symptoms and three-dimensional deformity parameters in ADS. It provides additional axial information beyond coronal and sagittal assessment, but should not be used alone to explain global imbalance or predict deformity progression. Because AVR was measured on supine CT whereas SVA/CVA were obtained from standing radiographs, and some clinical confounders were unavailable for adjustment, these findings should be interpreted as associations rather than causal evidence.
OBJECTIVE: To evaluate the clinical and radiographic significance of supine CT-measured apical vertebral rotation (AVR) in adult degenerative scoliosis (ADS).
METHODS: A total of 163 patients with ADS were retrospectively included. Clinical outcomes included low back pain visual analog scale (VAS), leg pain VAS, Japanese Orthopedic Association (JOA) score, and Oswestry Disability Index (ODI). Radiographic parameters included sagittal vertical axis (SVA), coronal vertical axis (CVA), apical vertebral translation (AVT), lumbar lordosis (LL), thoracolumbar kyphosis, pelvic parameters, coronal Cobb angle, and AVR. AVR was measured on supine axial CT images using Ho's method. Reproducibility was assessed using ICC(2,1). Correlation, multivariable regression, sensitivity, and exploratory interaction analyses were performed.
RESULTS: All radiographic measurements showed excellent reproducibility, with an AVR ICC(2,1) of 0.999. AVR correlated with worse pain and functional scores and with multiple radiographic parameters In multivariable linear regression, SVA, AVT, and Cobb angle were independently associated with AVR. When SVA and CVA were analyzed as continuous outcomes, AVR remained independently associated with SVA, but not with CVA. In the threshold-defined global imbalance analysis, AVR remained independently associated with global imbalance after excluding SVA and CVA from the multivariable model (OR = 1.108, 95% CI: 1.036-1.184, P = 0.003). Sensitivity analyses supported the robustness of this association. No significant interaction was found between AVR and SVA or CVA.
CONCLUSIONS: Supine CT-measured AVR is associated with clinical symptoms and three-dimensional deformity parameters in ADS. It provides additional axial information beyond coronal and sagittal assessment, but should not be used alone to explain global imbalance or predict deformity progression. Because AVR was measured on supine CT whereas SVA/CVA were obtained from standing radiographs, and some clinical confounders were unavailable for adjustment, these findings should be interpreted as associations rather than causal evidence.