Study design <p>A retrospective study.</p> Objectives <p>This study aims to investigate the relationship between the resection of ossification of the nuchal ligament (ONL), its morphological features, and cervical stability following modified laminoplasty.</p> Methods <p>We retrospectively reviewed the data of patients diagnosed as degenerative cervical myelopathy (DCM) who underwent modified laminoplasty with muscle-ligament complex (MLC) reconstruction in our hospital between July 2018 and October 2022. Demographic information (e.g., age, gender), cervical sagittal parameters, cervical angular displacement (AD), cervical horizontal displacement (HD), range of motion and patient-reported outcomes were compared between patients with and without ONL.</p> Results <p>The cervical AD at C4-C5, C5-C6 and cervical HD at C5-6 were significantly higher in ONL (+) group than ONL (-) group before surgery and at the 24-month follow-up time (<i>p</i> &lt; 0.05, all). The AD and HD at C4-C5 and C5-C6 were higher in ONL (+) segments before surgery and at the 24-month follow-up (<i>p</i> &lt; 0.05, all). But the values of AD or HD were lower in ONL (+) segments at 3- or 6-month follow-up (<i>p</i> &lt; 0.05, all). ONL (+) group with two or more consecutive segments demonstrate significantly increased cervical AD and HD at the C4-C5 level after a 24-month follow-up period (<i>p</i> &lt; 0.01, both).</p> Conclusion <p>Resection of the ONL, particularly involving ≥ 2 cervical segments, is moderately associated with an increased likelihood of cervical instability and abnormal sagittal alignment in long-term follow-up after laminoplasty. Reconstruction of the MLC during laminoplasty may enhance cervical stability in the early follow-up period. For DCM patients with long segmental ONL, more attention should be paid to protecting the MLC structure during posterior cervical surgery.</p> Clinical trial number <p>Not applicable.</p>