Developmental aspects of the hip in juvenile chronic arthritis. A radiological assessment.

The aim of this study in sero-negative juvenile chronic arthritis was to examine the radiological changes in the hip joints in relation to age and mode of onset of disease. Particular attention was paid to periods of complete immobilization or reduction in weightbearing, irrespective of clinical hip involvement. Twenty-two children with an early onset of disease (i.e. less than 5 years) with clinical hip involvement were compared with 12 similarly aged children without clinical hip involvement, and 22 children with a later onset but with clinical hip involvement. In all the children with an early onset of disease the initial radiographic findings were developmental rather than destructive. In those with clinical hip involvement, destructive changes supervened, while those with later onset had destruction as the first feature, often followed by the development of protrusio acetabula. The 12 children without clinical hip involvement who had prolonged periods of non-weightbearing in early life, usually because of knee involvement, showed developmental abnormalities. These findings suggest that weightbearing should be encouraged, to promote the normal development of the hips.