Perthes' disease of the hip in Liverpool.

A survey of Perthes' disease of the hip in three regions of England showed a higher incidence in the Mersey region compared with Trent or Wessex. To explore this further a case register was set up in Liverpool. Analysis of all new cases that occurred in Liverpool and adjacent parts of Knowsley and Sefton during 1976-81 showed a steep gradient with social class, ranging from 7.7/100 000 children in the higher classes to 26.3/100 000 in social class V. The inner city of Liverpool, which has been shown to be underprivileged, had the highest yearly incidence of the disease ever reported--21.1 cases/100 000 children aged 14 years and under. The associations with poverty support the hypothesis that undernutrition is a causative factor in the disease.