Age at Initial Surgery and Surgical Burden in Congenital Spinal Deformity

Background: Congenital spinal deformities associated with multiple vertebral anomalies often require surgical correction during growth; however, the relationship between age at initial surgery and cumulative treatment burden remains insufficiently characterized. Objective: To evaluate whether age at first surgery is associated with surgical burden and radiographic outcomes in children with congenital spinal deformity treated with conventional posterior instrumented fusion. Methods: In this retrospective single-center cohort study, 32 children treated between 2019 and 2024 were stratified by age at initial surgery into two groups: ≤6 years (n = 13) and 7-12 years (n = 19). Planned staged procedures and growth-friendly techniques were excluded. Surgical burden was assessed as the total number of procedures, procedures per patient-year, and high surgical burden, defined as ≥3 procedures. Radiographic outcomes included postoperative Cobb angle and correction percentage. Adjusted analyses were performed using Poisson regression with log follow-up as an offset term, logistic regression, and linear regression. Results: Baseline deformity severity was similar between groups (mean preoperative Cobb angle, 45.2 ± 19.0° vs. 43.1 ± 21.6°; p = 0.61). Both groups showed significant within-group improvement after surgery (p < 0.001), with no significant between-group difference in correction percentage (61.5 ± 35.2% vs. 64.8 ± 30.6%; p = 0.78). The total number of procedures and procedures per patient-year were also comparable between groups (p = 0.21 and p = 0.58, respectively). However, high surgical burden was more frequent in the younger group (38.5% vs. 10.5%; p = 0.048). In adjusted analysis, older age at first surgery was associated with lower odds of high surgical burden (OR = 0.78; 95% CI: 0.61-0.99; p = 0.042), whereas no variable independently predicted correction percentage. Conclusions: Younger age at initial surgery was associated with a greater likelihood of high surgical burden, whereas the time-adjusted operation rate and early coronal correction were similar between groups.