Vertebral Body-Level Increased Signal Intensity in Cervical Ossification of the Posterior Longitudinal Ligament: Association with Segmental Hypermobility and Surgical Outcomes.

Introduction: Increased signal intensity (ISI) on T2-weighted magnetic resonance imaging at the vertebral body level in cervical ossification of the posterior longitudinal ligament (OPLL) may reflect dynamic cord compression. This study investigated the prevalence, radiographic characteristics, and surgical outcomes associated with vertebral body-level ISI in patients with OPLL. Methods: This retrospective study analyzed 95 patients with cervical OPLL who underwent surgery between 2013 and 2022. Patients were categorized on the basis of ISI location: group D (disc level, n=52) and group B (vertebral body level, n=23). Radiographic parameters including cervical alignment, range of motion (ROM), and K-line status were evaluated. Clinical outcomes were assessed using Japanese Orthopaedic Association (JOA) scores at 2-year follow-up. Results: Vertebral body-level ISI was observed in 24.2% of the entire cohort, accounting for 30.7% of patients with ISI. Group B indicated significantly greater local ROM (10.3±2.2° vs 5.8±2.6°, p<0.0001) and more pronounced flexion kyphosis than did group D, and predominantly anterior cord compression compared with group D. In group B, fusion surgery yielded superior outcomes to decompression alone (JOA recovery rate: 59.9±21.7% vs 18.7±20.9%, p=0.0061), despite most patients being K-line (+). Conclusions: Vertebral body-level ISI in cervical OPLL is associated with increased segmental mobility and flexion-related dynamic compression. These exploratory findings suggest that vertebral body-level ISI may warrant consideration of fusion surgery, even in K-line (+) cases. Prospective validation in larger cohorts is needed.