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

➢ For isolated cervical deformities in patients with good bone health, the upper instrumented vertebra can be C3 or C4.➢ For patients with global cervical deformity, poor bone health, planned 3-column osteotomies, or long fusion constructs, C2 may be an appropriate upper instrumented vertebra.➢ For patients with focal kyphosis, optimal sagittal alignment, and preserved bone stock, a lower instrumented vertebra cranial to the cervicothoracic junction is appropriate.➢ For patients with poor cervical sagittal alignment, a lower instrumented vertebra in the proximal thoracic spine, ranging from T1 to T3, may be appropriate.➢ For combined cervical and thoracolumbar spinal deformities, a lower instrumented vertebra in the lower thoracic or upper lumbar spine is appropriate. The sagittal stable vertebra or first lordotic vertebra concepts can be considered.