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

Bone mineral density (BMD) of the lumbar spine in patients with ossification of the posterior longitudinal ligaments of the cervical spine (OPLL) was measured to elucidate the relation of spinal ossification with systemic hyperostotic condition. BMD in the lateral projection had a statistically significant correlation with that in the anteroposterior projection, and the former was considered to reflect the condition more accurately than was the latter, which may include the ossified spinal ligaments. BMD of patients with continuous and mixed types of OPLL was higher than that of those with the segmental type. Patients with OPLL and ossification of the other spinal ligaments had higher BMDs than did those without ossification. These results suggest that the BMD of the lumbar spine may reflect the systemic hyperostotic tendency and advancement of the ossification.