C2-3 Interlaminar Bony Fusion Mitigates Long-Term Progression of Ossification of the Posterior Longitudinal Ligament Following Cervical Laminoplasty.

Abstract

Study DesignRetrospective cohort study.ObjectivesTo investigate the influence of spontaneous C2-3 interlaminar bony fusion on the long-term progression of ossification of the posterior longitudinal ligament (OPLL), and to assess its associated clinical and radiologic consequences following cervical laminoplasty.MethodsPatients who underwent cervical laminoplasty for myelopathy due to multilevel OPLL involving the C2-3 level and were followed for ≥5 years were analyzed. Patients were classified according to the presence of C2-3 interlaminar fusion. OPLL progression (anteroposterior [AP] and sagittal diameters), cervical range of motion (ROM), and patient-reported outcomes were compared. Multivariable linear regression and linear mixed-effects modeling assessed the adjusted association between fusion status and OPLL progression over time, controlling for key covariates.ResultsForty-nine patients met inclusion criteria. C2-3 interlaminar fusion independently predicted reduced AP (β = -1.439, <i>P</i> = .0031) and sagittal (β = -8.725, <i>P</i> = .0007) progression after adjustment for all confounders. Mixed-effects modeling confirmed a significantly flatter long-term progression trajectory in patients with interlaminar fusion. C2-7 ROM and patient-reported outcomes were comparable between groups.ConclusionsSpontaneous C2-3 interlaminar fusion is associated with attenuation of postoperative OPLL progression without compromising overall cervical motion or clinical outcomes. These findings suggest that C2-3 interlaminar fusion may function as a stabilizing postoperative phenomenon rather than an unfavorable radiologic change following cervical laminoplasty in multilevel OPLL patients.