Correlation of spinal cord compression angle and increased signal intensity on MRI in patients with ossification of posterior longitudinal ligament.

We retrospectively investigated the correlation between the spinal cord compression angle and increased signal intensity (ISI) in 118 patients with ossification of the posterior longitudinal ligament (OPLL). Patients were analyzed based on the presence and shape of ISI on magnetic resonance imaging. Various indicators, including the spinal cord compression angle, were measured through imaging examinations. Spearman's correlation and logistic regression were used for analyses. Significant positive correlations were observed between the ISI grade and the spinal cord compression angle, maximum spinal canal occupying rate, cervical range of motion, and segmental range of motion. The spinal cord compression ratio and Japanese Orthopaedic Association (JOA) score were negatively correlated with the ISI grade. Regression analysis revealed that the spinal cord compression angle and JOA scores were independent factors that significantly influenced ISI grade. The odds ratio of ISI was 3.858 (95% confidence interval: 0.974-15.278) when comparing the highest and lowest quartiles of the spinal cord compression angle. Patients with a spinal cord compression angle > 35° had more severe imaging manifestations. Thus, a spinal cord compression angle > 35° could serve as a significant indicator of OPLL severity, and greater attention should be focused on treating patients with larger spinal cord compression angles.