Changes in pelvic measurements and lumbar lordosis with age in children and adolescents.

Purpose: To investigate the changes in pelvic measurements and lumbar lordosis with age in children and adolescents and to find a relationship between pelvic parameters and lumbar lordosis to estimate appropriate lordosis in the adolescent idiopathic scoliosis surgery.

Methods: A retrospective analysis of 382 abdominal-pelvic CT scans was conducted, with pelvic incidence, sacral slope, pelvic tilt, supine lumbar lordosis, and a derived parameter L1 slope measurements performed. Participants were divided into three age groups: 3-10, 11-15, and 16-18 years. Statistical correlations are performed among parameters and between age groups.

Results: Showed that pelvic incidence, sacral slope, pelvic tilt and supine lumbar lordosis increased significantly with age, with pelvic incidence rising by 7.2° from childhood to late adolescence. Notably, L1 slope remained constant across age groups, suggesting its potential as a stable parameter during growth. Strong correlations were observed between sacral slope and supine lumbar lordosis (R = 0.904). Mathematical formulas for estimating supine lumbar lordosis from pelvic incidence (SLL = 0.714xPI + 12.297) and sacral slope (SLL = 1.19xSS + 2.22) were derived.

Conclusion: L1 slope as a stable parameter during the growth period is a potentially overlooked but critical parameter in pediatric spinal assessments. Derived mathematical formulas may offer clinical utility for surgical planning in adolescent idiopathic scoliosis.