Diagnostic Imaging of Cervical Ossification of the Posterior Longitudinal Ligament

Abstract

The range of ossifi cation in the ligaments of the cervical spine that can be examined using imaging include ossifi cation of the posterior longitudinal ligament (OPLL), ossifi cation of the yellow ligament (ligamentum fl avum) (OYL), ossifi cation of the anterior longitudinal ligament, and ankylosing spondylitis. OPLL is one of a group of diffuse idiopathic skeletal hyperostoses that can affect the various spinal ligaments. Cervical OPLL is the most common among this group and often leads to compression myelopathy. Clinical guidelines for diagnosing and treating OPLL were published in 2005 by a committee within the Japanese Orthopedic Association and funded by the Japanese Ministry of Public Health and Welfare [1]. This section describes the diagnostic imaging for cervical OPLL based on those clinical guidelines and on the research referred to by the guidelines. The presence of cervical OPLL is generally confi rmed on a lateral plain radiograph. Tomography and computed tomography (CT) are, however, much more sensitive for visualizing the detailed outlines of any ossifi ed mass. The guidelines committee proposed that the diagnostic criteria for OPLL include clear radiographic fi ndings as well as documentation of the clinical symptoms; thus, early small ossifi cation not visible on lateral plane radiography and that can be detected only by CT does not fulfi ll the diagnostic defi nition for OPLL [1]. Cervical OPLL