Computed tomography study of the relationship between pelvic incidence and bony contribution to lumbar lordosis in children.

There is little data regarding the relationship in children and how it may change with aging. The aim of this radiographic study was to define the relationship between pelvic incidence (PI) and segmental vertebral body lordosis through childhood. In 150 children, CT scans of the lumbar spine and pelvis were analyzed measuring PI, sacral table angle (STA), sacral kyphosis (SK), and segmental lordosis (SL) individually L1-L5. Children were grouped by age: (1) 0-60 months; (2) 61-120 months; (3) 121-185 months. Mean PI for the entire cohort was 40.4, mean SL for L1-0.6, L2 0.0, L3 1.8, L4, 4.7, and L5 11.4. There were 40 children in Group 1, 63 in Group 2 and 37 in Group 3. SL differed between age groups at all levels except at L2. L1 and L2 became more kyphotic with increasing age; L3, L4, and L5 became more lordotic with increasing age. The correlation between PI and SL at each level became stronger with increasing age. Similarly, the correlation between PI and STA and between PI and SK also became stronger with increasing age. As children mature, the relationship between PI and segmental lordosis at each level of the lumbar spine becomes stronger-the relationship between PI and lordosis trends toward that seen in the adult. Future work should aim to define when the adult PI-LL relationship is realized.