CRP and ossification of the posterior longitudinal ligament of the spine: Inflammatory parameters further distinguished the groups: C-reactive protein was elevated in the OPLL group (0.17 ± 0.22 vs. 0.14 ± 0.23 mg/dL, p < 0.001), and the erythrocyte sedimentation rate at 60 min was significantly higher (13.36 ± 8.94 vs. 10.45 ± 8.16 mm/h, p < 0.001).