Cervical sagittal alignment and its impact on degenerative cervical myelopathy outcomes.

Introduction: 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. Research question: This review synthesizes current evidence on alignment parameters and their clinical relevance in DCM management, with the primary aim of guiding surgical decision-making. Material and methods: 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. Results: 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. Discussion and conclusion: 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.