A slightly larger group of children have hips which are not safely in the socket or in whom the socket is shallower than it should be. In general girls are more likely to be affected that boys. The left hip is more often affected than the right. Most children who have slight instability of the hip at birth will get better on their own without the need for specific treatment. Nonetheless it is important to try to identify these children to ensure that the expected improvement occurs.
Babies undergo routine examination of their hips at different ages.
At birth they are checked by two tests called the Ortolani and Barlow tests. The baby is laid on his or her back and the hips are gently taken sideways. It is usually possible for a baby's hips to be taken fully out sideways. If the baby's hip does not move as fully as this it may be that the hip is not developing properly and further investigations and checks are necessary. In a young baby further investigation is usually by ultrasound but in an older child x-rays are more commonly helpful in establishing the diagnosis.