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The hip is where the thigh bone and pelvis meet. The thigh bone has a ball-shaped top. This ball fits into a cup shape area on the pelvis. Developmental dysplasia of the hip (DDH) is a problem with how these bones fit together. The exact problem can vary between children but may include:

• Ball of the thigh is loose inside the cup of the pelvis—makes the hip unstable
• Ball moves easily out of the cup—causing a dislocation of the hip
• Ball and cup do not meet at all
• The cup is improperly shaped

The Hip Joint

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The exact cause of DDH is not known. Some factors that may play a role include:

• How the baby is positioned in the womb
• Maternal hormones
• Genetics

Certain carrying or wrapping techniques may also affect the growth of the hip, especially methods that have the child tightly bound in a position with the hips straight out and turned in.

Factors that may increase your baby’s chance of developing DDH include:

• Family history of DDH
• Breech birth (feet first), especially in females
• Gender: More common in females than males
• Low levels of amniotic fluid during pregnancy
• Late delivery—birth after 42 weeks of pregnancy
• Birthweight greater than 8 pounds 13 ounces (4 kg)

DDH can make the hip unstable and loose. Symptoms may depend on the age of your child. They may include:

• Uneven folds in the area of the thigh or hip—may be visible in newborns
• Poor mobility and flexibility when beginning to crawl—around 9 months
• One leg shorter than the other may beginning to stand at 10-11 months
• Limping, lurching, walking on toes, or other unevenness in walk at about 1 year

DDH more commonly affects the left hip. Sometimes both hip joints are affected. The condition may be detected when the baby is born.

Your child's doctor will look for signs of DDH during the first physical exam, and every exam in the first year The hip will be moved gently to see if it makes a clunking or popping noise. This may indicate a dislocating hip.

The hip may also be assessed with:

• A test done by placing the baby on his or her back and checking the height of the knees.
• Looking for uneven folds in the hip or thigh
• Difficulty moving the hip outward

Detailed pictures of the hip may help confirm the diagnosis or determine treatment. The pictures can be made with:

• Ultrasound—in babies less than 4 months old or babies with risk factors but a normal physical exam
• X-rays—in babies older than 3 months

Talk with the doctor about the best treatment plan for your baby. Depending on your baby’s age and the severity of the condition, treatment options include:

• For newborns: a harness called Pavlik harness to keep the hip in place may be worn for 1-2 months
• For babies aged 1-6 months:
  • Harness to reposition the hip
  • Manual adjustment—the doctor moves bones into proper positions, and then places the baby in a lower body cast
• For babies aged six months to two years:
  • Manual adjustment
  • Hip surgery, then body cast
• For children over two years: hip surgery, then body cast

If your baby was diagnosed with DDH at birth, the doctor may not treat the condition until the baby is older than two weeks. Early DDH may improve on its own.

The doctor will monitor the hip during follow-up exams and x-rays. This will be done until your child is done growing.

Because the exact cause is unknown, it is difficult to prevent DDH. If you are pregnant and have a family history of DDH, tell your doctor.

Avoiding certain swaddling positions may also help decrease some types of hip dislocation.