Brief Overview about Cervical Sagittal Alignment and Balance

Abstract

Background: The cervical spine is uniquely adapted to allow for a wide range of motion including flexion, extension, and lateral bending. It consists of seven vertebrae stacked on top of each other, spinal ligaments, and the spinal cord which run within the spinal canal. The C1 and C2 vertebrae are anatomically different from other vertebrae while the others are almost identical. Normally, the cervical spine has a lordotic curvature. Myelopathy describes any neurologic deficit related to the spinal cord. When due to trauma, it is known as (acute) spinal cord injury. When inflammatory, it is known as myelitis. Disease that is vascular in nature is known as vascular myelopathy. The most common form of myelopathy, cervical spondylotic myelopathy (CSM), is caused by arthritic changes (spondylosis) of the cervical spine, which result in narrowing of the spinal canal (spinal stenosis) ultimately causing compression of the spinal cord. The concept of cervical spinal alignment has gained interest in the field of spinal deformity research over the last decade. However, the number of studies on normative data remain limited. The number of studies on cervical sagittal alignment have increased dramatically over the last several years. Broad areas of research focus in this space have been: (1) correlation of cervical alignment with thoracolumbar spine following surgical treatment; (2) novel measurement parameters correlating cervical spine and thoracolumbar-pelvic alignment including ‘T1 sagittal angle’ ( T1 slope), and thoracic inlet alignment and (3) correlation of health-related quality of life (HRQoL) and cervical radiographic alignment parameters such as cervical sagittal vertical axis.