This paper is a narrative review of normal cervical alignment, methods for quantifying alignment, and how alignment is associated with cervical
deformity,
myelopathy, and adjacent-segment disease (ASD), with discussions of health-related quality of life (HRQOL). Popular methods currently used to quantify cervical alignment are discussed including cervical
lordosis, sagittal vertical axis, and horizontal gaze with the chin-brow to vertical angle. Cervical
deformity is examined in detail as
deformities localized to the cervical spine affect, and are affected by, other parameters of the spine in preserving global sagittal alignment. An evolving trend is defining cervical sagittal alignment. Evidence from a few recent studies suggests correlations between radiographic parameters in the cervical spine and HRQOL. Analysis of the cervical regional alignment with respect to overall spinal pelvic alignment is critical. The article details mechanisms by which cervical kyphotic
deformity potentially leads to ASD and discusses previous studies that suggest how postoperative sagittal malalignment may promote ASD. Further clinical studies are needed to explore the relationship of cervical malalignment and the development of ASD. Sagittal alignment of the cervical spine may play a substantial role in the development of cervical
myelopathy as cervical
deformity can lead to
spinal cord compression and cord tension. Surgical correction of cervical
myelopathy should always take into consideration cervical sagittal alignment, as
decompression alone may not decrease cord tension induced by
kyphosis. Awareness of the development of postlaminectomy
kyphosis is critical as it relates to cervical
myelopathy. The future direction of cervical
deformity correction should include a comprehensive approach in assessing global cervicalpelvic relationships. Just as understanding pelvic incidence as it relates to lumbar
lordosis was crucial in building our knowledge of thoracolumbar
deformities, T-1 incidence and cervical sagittal balance can further our understanding of cervical
deformities. Other important parameters that account for the cervical-pelvic relationship are surveyed in detail, and it is recognized that all such parameters need to be validated in studies that correlate HRQOL outcomes following cervical
deformity correction.