[Histopathological findings of the ossification of the posterior longitudinal ligament of the cervical spine and their significance (author's transl)].

Characteristics features of the histopathological findings of the ossification of the posterior longitudinal ligament (OPLL) of the cervical spine are as follows: 1. In the segmental type of OPLL, the ossification of fibers usually initiates near the posterior border of the vertebral body and in those fibers which attach to the edge of the vertebral body. 2. At the axial ossifying point, degeneration of fibers occurs and enchondral ossification process follows, while in other part of the ossifying area, different types of ossification processes may also occur. 3. In association with OPLL, especially in the hyperostotic type, other paraspinal soft tissues may exhibit proliferation of the cartilage cells with or without ossification, implying the presence of ossifying tendency of the whole body. Of these tissues, the periosteum, the annulus fibrosus and/or the dura mater demonstrate proliferating changes in direct contact with OPLL, and the involvement of the periosteum precedes the other changes including OPLL, suggesting some influence from the vertebral side over the ossifying process of the paraspinal soft tissues.