Bone mineral density in patients with ossification of the posterior longitudinal ligament in the cervical spine.

Bone mineral density (BMD) has not been clearly determined in patients with ossification of the posterior longitudinal ligament (OPLL) in the cervical spine. BMD in patients with OPLL was measured in the third vertebral body in the lateral projection and in the distal part of the radius in the anteroposterior projection using dual-energy X-ray absorptiometry (DXA). Patients with OPLL had significantly higher BMD than healthy controls in both the lumbar spine and radius. Observing BMD by gender and age group, high BMD was recognized especially in female patients over 60 years of age. Significantly increased BMD was observed in patients with ankylosing spinal hyperostosis (ASH) in addition to OPLL. These findings suggest that patients with OPLL may tend to develop systemic hyperostosis, leading to the pathological ectopic ossification observed in OPLL.