Some etiologic factors in Perthes' disease.

The cause of Perthes' disease remains unknown but the nature of the problem and area of research have now become more clearly defined. Genetic and environmental aspects are here reviewed, with the conclusion that there is no good evidence for genetic factors in the great majority of patients. Retarded growth and delayed skeletal maturation have been shown to be already present at the time of diagnosis of the disease. These children are more likely to have been breech births, born late in the family of older-than-average parents. A high proportion of the children come from low income homes. It seems that the study of the relevant environment must be extended back in time to include the prenatal surroundings. The question arises whether the delay in skeletal maturation (for whatever reason) itself makes the femoral head more susceptible to infarction, or whether there is a common predisposing factor during intrauterine development which effects both the rate of maturation and the femoral head itself, leading to Perthes' disease at a later age. The disorder is perhaps more one of developmental sequences than a specific disease process of the femoral head. For the moment the disease must take its place among the nongenetic developmental disorders of unknown etiology, but with the understanding that the undersized, disadvantaged child is at a greater risk than normal.