Clinical Manifestation of Cervical Ossification of the Posterior Longitudinal Ligament

Abstract

Ossification of the posterior longitudinal ligament (OPLL) of the spine is found radiographically at any level of the whole spine, including the cervical, thoracic, and lumbar spine; the cervical spine is the level most frequently encountered (Fig. 1). The shape and volume of OPLL is quite varied. OPLL is sometimes found in a very limited area but often extends to the wide area behind the posterior wall of the vertebral body and disk of the spine and occupies from less than 10% to more than 50% of the anterior part of the spinal canal. The appearance of OPLL observed in radiographs is classified into four types: (1) segmental, (2) continuous, (3) mixed, and (4) localized [1,2]. The shape is also quite irregular. OPLL is one of the important factors in stenosis of the spinal canal, thus causing the spinal cord and the nerve roots to be entrapped or compressed in various ways.