[Ossitication of the posterior longitudinal ligament of spine (OPLL)].

Ossification of the posterior longitudinal ligament of spine (OPLL) is a disease that causes ectopic ossification of the ligament to develop in the spinal canal. Although OPLL causes severe neurologic symptoms caused by spinal cord compression, the mechanisms of OPLL initiation and promotion have not yet been identified. It is a common disease with an incidence of 2-4% in the middle age and older populations of Asian countries, whereas lower incidence has been reported in non-Asian countries. The disorder is believed to be a collective result of heterogeneous etiopathologic factors affecting the spinal ligament.