Epidemiology of Osteonecrosis in Japan

Disease incidence an important parameter in epidemiological research. In Japan, the annual incidence of osteonecrosis of the femoral head (ONFH) was 1.18– 1.77 per 100,000 people from 2004 to 2014. The annual prevalence of ONFH was 5.9–18.2, which is increasing over time. The male-to-female ratio was 1.25:1.45, indicating that ONFH occurs more frequently among men than among women in Japan. In 2004, there was a single peak of age distribution in men in their 40 s and women in their 30 s, while a single peak in women moved to their 60 s in 2014. Systemic corticosteroid administration is mostly associated with ONFH in Japanese female patients, while habitual alcohol intake is associated with ONFH in Japanese men patients. The prevalence of alcohol-associated ONFH was markedly high in Tokyo and Okinawa, regardless of sex, suggesting that there are regional characteristics for different risk factors of ONFH. Smoking ≥20 cigarettes per day showed a significant and moderate correlation in men.