Differential Risk Factors for Proximal Junctional Kyphosis Between T8-T10 and T11-L1 Upper Instrumented Vertebrae in Adult Spinal Deformity

While preoperative proximal junctional angle is a universal predictor, surgeons should consider avoiding the thoracolumbar junction for osteoporotic patients or for those requiring large lordosis corrections, and in T8-T10 fusions, particular attention should be paid to age-adjusted alignment targets and patient age. These findings may guide UIV-level-specific surgical planning to mitigate PJK risk.