Natural History of Ossification of the Posterior Longitudinal Ligament (OPLL)

Abstract

Ossification of the posterior longitudinal ligament (OPLL) is an important disease-causing spinal cord symptom. The timing of surgery and indication of preventive surgery have yet to be concluded. The main cause is the lack of research on the natural history of the onset of spinal cord symptoms of this disease. The author will introduce the research results of the single- and the multicenter facilities that have been conducted on the natural history of the clinical symptoms of OPLL and also mention the predictive factors of the onset of neurological symptoms in this disease. The Kaplan–Meier estimate of myelopathy-free survival among patients without myelopathy at the first visit was 71% at 30 years follow-up. The author examined the risk factor for the development of myelopathy in patients with asymptomatic ossification of the posterior longitudinal ligament by a multicenter prospective study. On univariate and multivariate logistic regression analysis, the development of myelopathy was significantly associated with spinal canal stenosis ratio, large range of motion of the cervical spine, and lateral-deviated type OPLL. The knowledge of natural history of this disease is essential for the treatment of this disease and further research in All Japan is desired in the future.