Correlation between the Size of Cervical Ossification of the Posterior Longitudinal Ligament and Bone Mineral Density

Abstract

Abstract Objective Bone mineral density (BMD) has been shown to increase in patients with ossification of the posterior longitudinal ligament (OPLL). However, the correlation between the OPLL size and BMD has not been studied yet. This study aimed to investigate the correlation between the size of the OPLL and BMD. Methods This cross-sectional study enrolled 84 patients who underwent cervical OPLL surgery and preoperative examinations with both computed tomography (CT) and dual-energy X-ray absorptiometry (DXA) between January 2015 and March 2021. The maximal OPLL occupying the cervical spine lesion (levels C2–7) was identified from axial images of the preoperative cervical spine CT scans, and the anterior-posterior diameter, area of the cervical spinal canal, and OPLL were measured at this location. BMD was measured in the lumbar spinal levels L1–4, femoral neck, trochanteric area, intertrochanteric area, and total femur area using DXA. Results The average OPLL-occupying diameter ratio of the cervical spine positively correlated with the average Z-score of the lumbar spine (r = 0.22, P < 0.05). The average OPLL-occupying area ratio of the cervical spine was positively correlated with the average T-score and Z-score of the lumbar spine (r = 0.22, P < 0.05 and r = 0.24, P < 0.05, respectively). Conclusion The axial size of the cervical OPLL is positively correlated with the BMD of the lumbar spine. Since the underlying mechanism of OPLL development remains unknown, these findings may improve the understanding of its pathogenesis.