Clinical presentation:
11 year old boy with pain in right hip.

The centre of mass of the capital epiphysis of the right femur is no longer in-line with its neck. There is lateral migration of the metaphysis relative to the epiphysis and the perceived height of the epiphysis is reduced. There is no visible spur on the lateral side. The epiphyseal plate appears widened. Although the right femur is rotated, the appearance suggests cortical thickening of the proximal metaphysis of the right femur. There is an additional band of bone density crossing the neck of the right femur.

The projected size of the right obturator ring indicates the rotation of the pelvis, imposed by the weight of the right thigh and the relative reduction in flexibility of the right hip joint in a supine view on the X-ray table. This is a useful, though non-specific, sign for localizing joint problems.