The epidemiology of Perthes' disease.

Epidemiologic studies in Britain have shown that the incidence of Perthes' disease is higher in children from families of low socioeconomic status. The disease is associated with urban areas. The highest annual incidence recorded to date is 15.6 per 100,000 children younger than 15 years of age, in Liverpool, England. Within Liverpool, the incidence is higher in the inner city wards. The epidemiology of the disease points to major environmental influences in the etiology; these are associated with poverty. A study of time trends in Dortmund, Germany, supports this conclusion. It is unclear whether the impaired skeletal maturation of children with Perthes' disease is a characteristic of the patients alone or the families or communities they belong to. The low incidence in people of African and Chinese descent may reflect ethnic differences in maturation. The disease may have a major determinant acting at a critical stage of early life. Reported associations with congenital malformations are inconclusive evidence of a prenatal determinant. Rather, the normal birthweight and absence of association with known prenatal influences suggest a determinant acting in early postnatal life.