Diagnosis of Developmental Dysplasia of the Hip
A doctor can determine whether a hip is dislocated or likely to become dislocated by gently pushing and pulling on the child's thighbones to see if they are loose in their sockets. In one commonly used diagnostic test, a child lies on a flat surface and his or her thighs are spread out to check the hips' range of motion.

A second test brings the knees together and attempts to push the femoral head out of the socket. It is during these tests that the doctor will hear a "click," which may indicate a dislocation. These maneuvers are done at routine checkups until babies are walking normally.

Sometimes a doctor will recommend an X-ray or ultrasound to get a better view of a dislocated hip. X-rays (which only take pictures of bones) are done with older kids, while ultrasounds (which take pictures of bones and soft tissues) are better for babies younger than 3 months old because their hip tissue has not yet hardened into bone.