Incidence of hip fracture in Niigata, Japan in 2004 and 2010 and the long-term trends from 1985 to 2010
The incidence of the femoral neck fractures in 1985 was studied in Niigata Prefecture, Japan, which is on the “Japan Sea” at the central area of the Main Island of Japan. The author visited all hospitals within Niigata Prefecture, to study radiographs and records of patients who sustained femoral neck fractures. On October 1, 1985, the population of Niigata Prefecture was 2,474,829 (1,202,873 males and 1,271,956 females). The population over 65 years of age was 319,305, 12.9% of the total population (129,252 males and 190,053 females). During 1985, there were 677 fractures of femoral neck (183 males and 494 females, i.e. 1∶2.7). Its incidence over 65 years of age was 9.3 in males and 23.9 females per 10,000 population/year. The ratio of cervical and trochanteric fractures was 231∶446 (1∶1.9), the latter amounting to two thirds of the femoral neck fractures. The age specific incidence in Niigata Prefecture showed an exponential increase with increasing age like in Sweden or in the USA, but the age-adjusted incidence in Niigata Prefecture was one-fourth or one-fifth of that in those countries.