Clinics in diagnostic imaging (55). Ossification of the posterior longitudinal ligament

Ossification of the posterior longitudinal ligament (OPLL) of the cervical spine associated with diffuse idiopathic skeletal hyperostosis is described in a 70-year-old Caucasian man presenting with a rapidly progressive myelopathy. The acute nature of his myelopathic symptoms and cervical canal stenosis necessitated posterior decompressive surgery. Four other patients with OPLL are presented to illustrate the spectrum of imaging findings. The computed tomographic features of OPLL are distinctive.A 2-5 mm thick linear ossified strip along the posterior vertebral margin usually at mid cervical (C3 to C5) level characterises the condition. Magnetic resonance (MR) imaging is valuable in excluding possible cord damage and associated disc lesions prior to surgery. A calcified central sequestrated disc is the only condition that may be mistaken for the segmental and retrodiscal forms of OPLL In a clinical setting of compressive myelopathy, it is pertinent to distinguish between these two conditions since a sequestrated disc has a more favourable surgical prognosis. The merits and relevance of anterior and posterior surgery together with their possible complications are outlined.