Association between LIV + 1 bone mineral density asymmetry and distal adding-on phenomenon in adolescent idiopathic scoliosis.
Greater LIV+1 bone density asymmetry is associated with distal adding-on after scoliosis surgery
Association between LIV + 1 bone mineral density asymmetry and distal adding-on phenomenon in adolescent idiopathic scoliosis.
Distal adding-on phenomenon remains a common complication following corrective surgery for adolescent idiopathic scoliosis (adolescent idiopathic scoliosis).
This study aimed to characterize the spatial distribution of vertebral bone mineral density (bone mineral density) across the scoliotic spine and to examine whether preoperative bone mineral density asymmetry at the vertebra immediately distal to the lowest instrumented vertebra (LIV + 1) may serve as a complementary biomechanical risk marker for postoperative distal adding-on within existing LIV-selection frameworks.
This retrospective cohort study included 90 patients with adolescent idiopathic scoliosis who underwent posterior spinal fusion and had preoperative full-spine computed tomography scans.
risk of adding-on jumps 24-fold when asymmetry crosses the cutoff
The mean whole-spine bone mineral density was 0.85 ± 0.14 g/cm 2 .
No significant difference was observed between the overall concave and convex sides (p = 0.510), although region-specific asymmetry patterns were identified.
Distal adding-on occurred in 15 patients (16.7%).
LIV + 1 bone mineral density asymmetry demonstrated good discrimination (AUC = 0.865, 95% CI 0.77-0.96), with an optimal cutoff value of 0.112 g/cm 2 .
Vertebral bone mineral density in adolescent idiopathic scoliosis exhibits a region-specific asymmetric distribution pattern.
Increased preoperative LIV + 1 bone mineral density asymmetry is associated with postoperative distal adding-on and may provide complementary, hypothesis-generating biomechanical information for risk stratification and distal fusion-level planning.
These findings should be validated in larger cohorts before bone mineral density asymmetry is used as a stand-alone determinant of LIV selection.