Study design: Retrospective radiographic reliability study. Objective: To assess the interobserver reliability and SEM of vertebral pelvic angles (VPAs) in pediatric idiopathic scoliosis and compare them to traditional sagittal Cobb measurements. Summary of background data: Vertebral pelvic angles have demonstrated utility in assessing sagittal alignment in adult spinal deformity due to their relative insensitivity to rotational distortion and inconsistent visualization of endplates. Their reliability in juvenile and adolescent idiopathic scoliosis (JIS/AIS) has not been established, despite potential advantages over conventional Cobb-based parameters. Methods: Seventy-three patients aged 10 to 21 years with JIS or AIS undergoing posterior spinal fusion were included. Three independent raters measured preoperative and postoperative VPAs C2PA, T4PA, L1PA, pelvic incidence (PI), pelvic tilt (PT) and conventional sagittal Cobb angles (L1–L4 lordosis, L4–S1 lordosis, T4–T12 kyphosis, and C2–C7 lordosis) using standardized EOS lateral radiographs. Interobserver reliability was assessed using intraclass correlation coefficients (ICCs). SEM was calculated for each parameter using SEM. Results: Seventy-three patients (mean age 15 ± 2.4 yr, 78% females) were included. Most patients were skeletally mature, with 83% at Risser stage ≥4 and 71% at Sanders stage ≥7. Lenke type 1 (38.9%) and type 2 (26.4%) curves were most common. VPAs demonstrated good to excellent interrater reliability: T4PA and C2PA had very good to excellent ICCs (0.89 and 0.94), while L1PA, PT, and PI showed good agreement (ICCs 0.85, 0.86, and 0.83). Corresponding SEMs ranged from 1.8° to 6.1°. In contrast, sagittal Cobb angles showed moderate ICCs (T4–T12 kyphosis, L1–L4 and L4–S1 lordosis, 0.69, 0.67, and 0.56, respectively) with higher SEMs (up to 6.5°). Conclusion: VPAs provide more reliable and reproducible measurements of sagittal alignment in pediatric idiopathic scoliosis than conventional Cobb methods, particularly in regions affected by rotational deformity. Their use may improve radiographic assessment and surgical planning in this population.
Collar et al. (Fri,) studied this question.