Yukio Kinjo

Evaluation of Bone Mineral Densities in Ossification of Posterior Longitudinal Ligament Using Dual-Energy X-Ray Absorptiometry

Ossification of posterior longitudinal ligament (OPLL) is an abnormal ossification of the spinal ligament and sometimes causes severe compressive myelopathy. Because of frequent association with ossification of other spinal and skeletal ligaments, OPLL has been classified as a type of ankylosing spinal hyperostosis (ASH) [1], or diffuse idiopathic skeletal hyperostosis (DISH) [2,3]. Pathological chondral ossification and bone remodeling were observed following the thickening of the ligaments [4], but the etiology remains unknown. It is considered that both local factors, such as mechanical stress or bone morphogenic factors, and generalized factors such as heredity or hormones may play a role in ossification. The purpose of this study is to determine whether bone mineral densities of OPLL patients can be used as an indicator of generalized hyperostotic inclination. This was done by comparing their bone mineral densities (BMDs) with those of normal subjects.