Cervical sagittal alignment and its impact on degenerative cervical myelopathy outcomes

Degenerative cervical myelopathy (DCM) is a progressive spinal cord disorder driven by static compression and dynamic instability. Cervical sagittal alignment has recently emerged as a potential factor influencing both pathogenesis and surgical outcomes.

This review synthesizes current evidence on alignment parameters and their clinical relevance in DCM management, with the primary aim of guiding surgical decision-making.

A narrative literature review was performed, analyzing radiological parameters of cervical alignment, their normative thresholds, and associations with functional outcomes. Both cranio-cervical and subaxial metrics were examined, alongside emerging global alignment concepts.

Key parameters include C2-C7 sagittal vertical axis (SVA), cervical lordosis (CL), T1 slope (T1S), and the T1S-CL mismatch. Malalignment is generally defined as SVA >40 mm, CL < 15°, or T1S-CL > 20°. Increased SVA and cervical kyphosis correlate with reduced mJOA scores and poorer surgical results. Alignment also informs surgical strategy: anterior approaches are favored in kyphosis or ventral compression, while posterior techniques are preferred in lordotic or neutral spines. Novel measures such as the C2-T1 Pelvic Angle (CTPA) seek to contextualize cervical alignment within global sagittal balance. Evidence further suggests reciprocal cervical adaptations following thoracolumbar correction.

Cervical sagittal alignment is clinically relevant in DCM pathophysiology and surgical decision-making. While correlations between alignment parameters and outcomes are established, robust evidence defining corrective thresholds remains limited. Prospective studies are required to validate these measures and refine realignment strategies in DCM.