The importance of standardised radiographs when assessing hip dysplasia.

The reliability of radiological criteria in the diagnosis of congenital dislocation of the hip is discussed. In a review of 20 normal infant patients the variability of the radiographic relationship between the ossific nucleus of the proximal femoral epiphysis and the acetabulum is identified. Hip arthrography in 10 patients and pathological examination of femoral heads confirm that the ossific nucleus lies superiorly within the infant femoral head and may be displaced from the true centre of the femoral head by up to 40% of it's radius. As the ossific nucleus of the capital femoral epiphysis is shown to originate eccentrically within the spherical cartilaginous anlage it is suggested that standardisation of hip radiographs is required in the routine clinical assessment of the infant hip, particularly in the presence of dysplasia.