Sagittal balance analysis and treatment rationale for young patients with symptomatic lumbosacral transitional vertebrae.

Lumbosacral transitional vertebrae (LSTV) are a common anomaly in 7-36% of the population. LSTV can contribute to mechanical low back pain and increase the risk of early degeneration in cranial segments due to hypermobility and stress. This study analyzed sagittal balance in young symptomatic LSTV patients and tried to identify compensatory mechanisms that may explain early degeneration. Nineteen symptomatic and skeletally mature subjects with LSTV were retrospectively identified. Imaging included standing biplanar spine radiographs and supine lumbar MRI. Sagittal balance parameters were measured, and LSTV were classified using the Castellvi classification. Vertical mid-vertebral angle differences were calculated using MRI and lateral radiographs. The cohort included 17 females and 2 males (mean age 16 ± 3 years). Mean pelvic incidence was 67°±8°. L1-S1 lordosis averaged 61°±10°, L4-S1 lordosis was 10° lower than expected, and L4-L5 lordosis was higher than literature values. Thirteen patients had L4-L5 discopathy, with nine showing additional abnormalities such as interspinous ligament edema or posterior facet hypertrophy. In our study, LSTV was associated with L5-S1 disc hypoplasia and altered lumbar lordosis, leading to compensatory L4-L5 hyperextension. These findings suggest early degeneration may result from abnormal lordosis distribution. Treatment should aim to optimize lordosis distribution to reduce stress on adjacent segments.