The C 2-C 7 sagittal vertical axis (SVA) is an essential biomechanical parameter for evaluating cervical spine alignment, and it is integral to the pathogenesis, progression, and prognosis of cervical spine disorders. This parameter is widely used in evaluating cervical sagittal balance and functional status. Internationally, a C 2-C 7 SVA of less than 25 mm is considered within the cervical range for sagittal balance, while values exceeding 40 mm indicate cervical sagittal imbalance or deformity. An increased C 2-C 7 SVA disrupts cervical spine biomechanics, leading to heightened static and dynamic loads on the cervical musculature. This, in turn, results in muscle fatigue and discomfort. In the short term, patients may experience axial neck symptoms, while a sustained elevation in SVA over time significantly raises the risk of cervical disc degeneration, radiculopathy, and myelopathy. Additionally, a higher C 2-C 7 SVA postoperatively places excessive stress on adjacent spinal segments, which can accelerate degeneration of intervertebral discs and facet joints, contributing to adjacent segment degeneration. Both short-term and long-term postoperative evaluations have shown that an increase in C 2-C 7 SVA is typically associated with poorer surgical outcomes, whereas effective control of SVA values is closely linked to better functional recovery. Therefore, in clinical practice, maintaining C 2-C 7 SVA within the normal range (<25 mm) is critical not only for optimizing treatment results but also for significantly reducing postoperative complications and improving overall patient quality of life.

The C 2-C 7 sagittal vertical axis (SVA) is an essential biomechanical parameter for evaluating cervical spine alignment, and it is integral to the pathogenesis, progression, and prognosis of cervical spine disorders. This parameter is widely used in evaluating cervical sagittal balance and functional status. Internationally, a C 2-C 7 SVA of less than 25 mm is considered within the cervical range for sagittal balance, while values exceeding 40 mm indicate cervical sagittal imbalance or deformity. An increased C 2-C 7 SVA disrupts cervical spine biomechanics, leading to heightened static and dynamic loads on the cervical musculature. This, in turn, results in muscle fatigue and discomfort. In the short term, patients may experience axial neck symptoms, while a sustained elevation in SVA over time significantly raises the risk of cervical disc degeneration, radiculopathy, and myelopathy. Additionally, a higher C 2-C 7 SVA postoperatively places excessive stress on adjacent spinal segments, which can accelerate degeneration of intervertebral discs and facet joints, contributing to adjacent segment degeneration. Both short-term and long-term postoperative evaluations have shown that an increase in C 2-C 7 SVA is typically associated with poorer surgical outcomes, whereas effective control of SVA values is closely linked to better functional recovery. Therefore, in clinical practice, maintaining C 2-C 7 SVA within the normal range (<25 mm) is critical not only for optimizing treatment results but also for significantly reducing postoperative complications and improving overall patient quality of life.