Principles of Level Selection for Instrumentation in Adult Thoracolumbar Spinal Deformity Surgery: Guidelines for Treatment.

➢ For primarily scoliotic deformities, the principles of the modular Lenke classification for adult idiopathic scoliosis can be used to guide level selection.➢ For hyperkyphotic deformities, the upper end vertebra is a suitable upper instrumented vertebra. The sagittal stable vertebra or the first lordotic vertebra is appropriate for the lower instrumented vertebra when fusion to the sacrum is not required.➢ Pelvic fixation can be considered in cases of sagittal and coronal malalignment when ≥4 levels of fusion to the sacrum are planned, L3 to L5 3-column osteotomies are planned, the patient has osteoporosis, or significant disc degeneration or stenosis exists at L5 to S1.