What is developmental dysplasia of the hip (DDH)?

Developmental dysplasia of the hip (DDH) is the name for a range of conditions of the hip. In mild cases, the ligaments and other soft tissues around the hip joint are not tight, and they allow the thighbone (femur) to move around more than normal in the hip socket. In more severe cases, the joint is loose enough to let the thighbone come partway out of the hip socket. This is called subluxation. Actual "dysplasia" is the most severe form of the condition. If a child has hip dysplasia, the socket is too shallow, more like a saucer than the deep cup that it should be. This allows the ball at the top of the thighbone (femoral head) to either partly or fully slip out of the socket (dislocate). DDH can affect one or both hip joints.

See pictures of normal hip anatomy in a child and a dislocated hip.

What causes DDH?

The exact cause of DDH is not known. But a number of risk factors can raise your child's chances of having DDH, including a family history of DDH and your baby's position in the womb and at birth.

What are the symptoms?

A baby with DDH may have:

• A hip joint that feels loose or slips out of place when examined.
• One leg that appears to be shorter than the other.
• Extra folds of skin on the inside of the thigh(s).
• A hip joint that moves differently than the other.

A child who is walking may:

• Walk on the toes of one foot with the heel up off the floor. The child walks this way because one leg is shorter than the other.
• Walk with a limp (or waddling gait if both hips are affected).

How is DDH diagnosed?

Usually, DDH is diagnosed during your newborn's physical examination. If your baby is older, DDH may be diagnosed during a well-baby checkup. But it may be more difficult to diagnose the condition in a baby older than 1 to 3 months, because the only outward sign may be less mobility or flexibility in the movement of the affected hip joint(s).

If the results of a physical examination are unclear, an imaging test such as an ultrasound or X-rays may be used to evaluate your child's hip joints.

How is it treated?

DDH is treated by moving your baby's upper thighbone into the hip socket and keeping it in place while the joint grows. A harness, called a Pavlik harness, is most often used to keep the joint in place in babies younger than 6 months. A hard cast, known as a spica cast, is used for older babies. Other forms of treatment, such as surgery or a brace, also may be needed.