[Updates on ossification of posterior longitudinal ligament. Epidemiology and pathogenesis of OPLL].

The study aimed for epidemiology and pathogenesis of ossification of the posterior longitudinal ligament of the cervical spine (OPLL) has been continued by The Investigation Committee of Japanese Ministry of Health, Labour and Welfare till now. As a result, the number of patients and frequency in Japan were clarified, and the epidemiology in foreign countries came to be reported, too. The association of various factors to development of OPLL was reported, but a hereditary factor is most important as the pathogenesis of OPLL. Genetic analysis with participation of all Japan research institutes has started t and it is expected to elucidate pathogenic gene of OPLL in the near future.