Topic Overview

What is developmental dysplasia of the hip (DDH)?

Developmental dysplasia of the hip (DDH) is a hip problem a baby is born with or that happens in the first year of life. In this condition, the top of the thigh bone doesn't fit securely into the hip socket. This problem may affect one or both hip joints.

In a normal hip, the thigh bone fits tightly into a cup-shaped socket in the pelvis, and 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, so the thigh bone (femur) moves around more than normal in the hip socket.
• In more severe cases, the hip socket is more like a saucer than the deep cup that it should be. As a result:
  • The ball at the top of the thigh bone (femoral head) may slip partway out of the hip socket. This is called subluxation.
  • The femoral head may slide completely out of the hip socket. This is called dislocation.

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 causes DDH?

The exact cause of DDH is not known. But some things can raise your child's chances of having it, including:

• Having a family history of DDH.
• Being the firstborn child.
• Being female.
• Being born buttocks-first (breech position).
• Having his or her legs swaddled tightly.

What are the symptoms?

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 DDH diagnosed?

It is usually diagnosed during a newborn's physical examination. A doctor will move the baby's legs and look and listen for signs of a problem.

If your baby is older, your doctor may diagnose DDH during the physical examination at a routine checkup. But it may be hard to diagnose in a baby more than 1 to 3 months old. That's because the only outward sign may be a hip joint that is less mobile or flexible than normal.

If the doctor suspects DDH but the results of a physical examination aren't clear, your child might need to have an imaging test of the hip joint, such as an ultrasound or X-ray.

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 deformed thigh bone or hip socket. A child who has surgery will probably need to wear a spica cast to position the hip joint 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 is successful, your child probably won't have any further hip problems. But get your child's hips checked regularly to make sure they continue to grow and develop normally.