Prevalence of ossification of the posterior longitudinal ligament of the cervical spine

ObjectivesTo determine the prevalence of ossification of the posterior longitudinal ligament (OPLL) in cervical spines in Koreans.MethodsWe reviewed the reports of the radiologic examination of cervical spines from January 2002 to September 2005 in Hanyang University Hospital, Seoul, Korea. OPLL was indicated by the presence of heterotopic ossification in the posterior longitudinal ligament on lateral cervical radiograph.ResultsAmong 11,774 adults aged 16 years or more, 71 cases of OPLL were found (0.60%). The male to female ratio was 42:29 (1.45:1). The highest prevalence was in patients aged 50–59 years. In terms of the types of OPLL, the continuous type was noted in 32.0% of the patients, the segmental type in 31.0%, the mixed type in 31.0%, and the localized type in 5.6%. C4, C5, and C3 were most commonly involved, in that order of frequency. Diffuse idiopathic skeletal hyperostosis, which is another common hyperostotic disorder, was also found in eight male patients.ConclusionsThe prevalence of cervical OPLL in Koreans was 0.60%, which was lower than that of Japanese and some previous western reports.