BACKGROUND: Ossification of the posterior longitudinal ligament (OPLL) is radiographically detectable in 3-6% of Asian individuals, although not all detectable OPLL cases lead to myelopathy. To date, it is unknown how many patients suffer from neurological symptoms due to OPLL. The purpose of this study was to investigate the epidemiology of symptomatic OPLL using Japan's national registry database. METHODS: We examined the registry data of patients with OPLL who held a certificate of medical subsidy from the Japanese Ministry of Health, Labor and Welfare. The study period was from January 1, 2011 to December 31, 2012. RESULTS: Registry data revealed that the incidence and the period prevalence of symptomatic OPLL were 0.005% (5 per 100,000 population) and 0.027% (27 per 100,000 population), respectively. OPLL occurred twice as often in men as in women. The peak age for onset of symptoms was 60-69 years. The mean Japanese Orthopedic Association (JOA) score was 9 points. Ninety percent of OPLL patients underwent surgery, and 90% of these surgeries were performed with a posterior approach. The most common indication for surgery was a JOA score of 11 points. CONCLUSIONS: According to registry data, the prevalence of symptomatic OPLL was less than one-hundredth of that of radiographically detected OPLL. This indicates that most cases of radiographically detectable OPLL may be asymptomatic. 2021 Journal of Spine Surgery. All rights reserved.
BACKGROUND: Ossification of the posterior longitudinal ligament (OPLL) is radiographically detectable in 3-6% of Asian individuals, although not all detectable OPLL cases lead to myelopathy. To date, it is unknown how many patients suffer from neurological symptoms due to OPLL. The purpose of this study was to investigate the epidemiology of symptomatic OPLL using Japan's national registry database. METHODS: We examined the registry data of patients with OPLL who held a certificate of medical subsidy from the Japanese Ministry of Health, Labor and Welfare. The study period was from January 1, 2011 to December 31, 2012. RESULTS: Registry data revealed that the incidence and the period prevalence of symptomatic OPLL were 0.005% (5 per 100,000 population) and 0.027% (27 per 100,000 population), respectively. OPLL occurred twice as often in men as in women. The peak age for onset of symptoms was 60-69 years. The mean Japanese Orthopedic Association (JOA) score was 9 points. Ninety percent of OPLL patients underwent surgery, and 90% of these surgeries were performed with a posterior approach. The most common indication for surgery was a JOA score of 11 points. CONCLUSIONS: According to registry data, the prevalence of symptomatic OPLL was less than one-hundredth of that of radiographically detected OPLL. This indicates that most cases of radiographically detectable OPLL may be asymptomatic. 2021 Journal of Spine Surgery. All rights reserved.
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Keywords:
Ossification of the posterior longitudinal ligament (OPLL); epidemiology; national registry; prevalence; symptomatic