Epidemiology and demographics of slipped capital femoral epiphysis in Japan: a multicenter study by the Japanese Paediatric Orthopaedic Association.

Anationwide survey of the epidemiology and demographics of slipped capital femoral epiphysis (SCFE) was carried out using questionnaires to investigate the incidence, clinical characteristics, and frequently used treatment procedures in Japan. Inquiries were sent to 2040 of the leading hospitals nationwide. Data were collected for the period between January 1997 and December 1999. Inquiries included onset age, sex, past medical history, type of slip, height, weight, and treatment procedure. Altogether, 314 cases were reported (237 boys, 77 girls) from 131 hospitals. The average annual incidence was estimated to be at least 2.22 for boys and 0.76 for girls for every 100 000 in the age group of 10- to 14-year-olds. These estimations are five times higher than the 1976 statistics from the eastern half of Japan. The average onset age was 11 years 10 months in boys and 11 years 5 months in girls. The most common treatment was surgery including in situ fixation (61.4%), osteotomies (25.9%), fixation after manual reduction (11.9%), and skeletal traction (0.9%). All patients except two were treated surgically. We concluded that SCFE has markedly increased during the last 25 years in Japan, and therefore further study of SCFE is needed to understand this disorder.