Normal Global Sagittal Alignment Radiographic Parameters in Patients Without Spinal Deformity

Study DesignRetrospective cohort study.ObjectivesThe purpose of this study was to report reference ranges for global sagittal alignment parameters stratified by age and sex in patients without spinal deformity.MethodsThis retrospective cohort study included consecutive patients undergoing biplanar full-body spine x-rays at a single institution, excluding those with spinal deformity or prior spine surgery. Global sagittal alignment parameters included cranial sagittal vertical axis to the sacrum (CrSVA-S), hip (CrSVA-H), knee (CrSVA-K), and ankle (CrSVA-A) as well as the cranium-hip-sacrum (CrHS), cranium-knee-sacrum (CrKS), and cranium-ankle-sacrum (CrAS) angles. Patients were stratified by age and sex, and ANOVA and multivariable logistic regression were used to compare groups, with age and sex as predictors of each radiographic parameter. Multivariable logistic regression models were created using age and sex as predictors, and each radiographic parameter as the outcome. In these models, age was treated as a continuous variable.ResultsA total of 518 patients were included, 253 (48.8%) male and 265 (51.2%) female, with ages ranging from 12 to 91 years old. In multivariable linear regression models, each 10-year increase in age was associated with a 0.6 cm increase in CrSVA-S (P < .001) and a 0.3 cm increase in CrSVA-H (P < .001). Conversely, age was associated with a 0.3 cm decrease in CrSVA-K per decade (P = .002), with no significant association observed between age and CrSVA-A. Male sex was associated with greater CrSVA-S (1.3 cm; P < .001), CrSVA-H (1.2 cm; P < .001), and CrSVA-A (1.2 cm; P < .001) compared to females. CrSVA-K did not differ significantly by sex.ConclusionThis study establishes reference values for normal global sagittal alignment to support operative planning and improve understanding of global sagittal alignment in spinal deformity.