What is developmental dysplasia of the hip (DDH)?

Developmental dysplasia of the hip (DDH) is a problem in a baby's hip joint. It may also be called developmental hip dysplasia. In DDH, the top of the thigh bone doesn't fit tightly into the hip socket. This problem may affect one or both hip joints. A baby may be born with it, or it may happen in the first year of life.

In a normal hip, the thigh bone (femur) fits snugly into a cup-shaped socket in the pelvis. It is held in place by muscles, tendons, and ligaments. But in DDH, the hip socket may be too shallow or the tissues around the joint may be too loose.

In mild cases, the ligaments and other soft tissues aren't tight. This lets the thigh bone move around more than normal in the hip socket. In more severe cases, the hip socket is more like a saucer than a deep cup. As a result, the ball at the top of the thigh bone may slide out of the hip socket.

It's important to get DDH treated early. The longer it goes on, the more likely it is to cause long-term hip problems.

What are the symptoms?

Developmental dysplasia of the hip (DDH) isn't painful, and your baby may not have any obvious signs of a hip defect. But some babies with this problem may have:

• One leg that seems shorter than the other.
• Extra folds of skin on the inside of the thighs.
• 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.
• Walk with a limp (or waddle if both hips are affected).

How is it treated?

Your child's hip socket won't form and grow properly if the ball at the top of the thigh bone doesn't fit snugly in the joint. So treatment focuses on moving the thigh bone into its normal position and keeping it in place while the joint grows.

Your child may need:

• A Pavlik harness. This device will probably be tried first if your baby is younger than 6 months. It holds your baby's legs in a spread position with the hips bent. The harness is able to make the hips normal most of the time.
• A hard cast, known as a spica cast. This is used for older babies. The cast keeps the hips in the proper position. It may have a bar between the legs to make it stronger.

Other forms of treatment that may be needed include:

• Braces or splints. These may be used instead of a Pavlik harness or spica cast. Or they may be used after surgery.
• Surgery. In some cases, this may be needed to correct a problem in the thigh bone or hip socket. A child who has surgery will probably need to wear a spica cast to hold the hip joint in position until it heals.
• Physiotherapy. A child who has been in a spica cast may need to do exercises to regain movement and build muscle strength in the legs.

If treatment works well, your child probably won't have any further hip problems. But you will need to get your child's hips checked regularly to make sure that they grow and develop normally.