How does sacral slanting change after lumbar hemivertebra resection in children?

To investigate the characteristics of coronal sacral slanting (CSS) in children with lumbar hemivertebra (HV) and to evaluate the changes of CSS following HV resection. CSS was defined as a sacral slanting angle > 5°. In this retrospective cohort study, 90 pediatric patients with congenital scoliosis who underwent posterior lumbar HV resection between June 2015 and June 2022 were reviewed. CSS and Cobb angle were measured preoperatively, at 3 months postoperatively, and at final follow-up. Associations of HV location and preoperative Cobb angle with CSS were assessed using correlation and multivariable linear regression, and longitudinal changes were analyzed using repeated-measures ANOVA. A total of 90 patients (50 male, 40 female; mean age 4.3 ± 2.4 years) were included, and complete CSS and Cobb-angle measurements were available at all three time points. Preoperatively, CSS > 5° was present in 55 patients (61.1%). More caudal HV location was associated with greater preoperative CSS (Spearman ρ = 0.508, P < 0.001). In multivariable analysis, both HV location and preoperative Cobb angle were independently associated with CSS (model R 2 = 0.399). Mean CSS decreased from 6.8 ± 4.4° preoperatively to 3.6 ± 3.1° at 3 months and 2.6 ± 3.3° at final follow-up [F(1.782,158.604) = 69.400, P < 0.001]. Mean Cobb angle decreased from 34.4 ± 10.1° to 3.5 ± 4.6° at 3 months and remained stable at 3.8 ± 5.5° at final follow-up [F(1.446,128.666) = 846.181, P < 0.001]. Among the 55 patients with preoperative CSS > 5°, mean CSS decreased from 9.5 ± 3.3° preoperatively to 4.9 ± 3.4° at 3 months and 3.5 ± 3.9° at final follow-up, and 44 patients (80.0%) achieved normalization to ≤ 5° at final follow-up. More caudally located lumbar HVs are associated with greater preoperative CSS, independent of curve magnitude. CSS improves substantially after HV resection, with a modest additional decrease during follow-up; however, the clinical significance of this late change remains uncertain because formal measurement-reliability testing was unavailable.