Developmental dysplasia of the hip (DDH)
What is DDH?
Developmental dysplasia of the hip is a condition of the hip joint that occurs once in every 1,000 live births. The normal hip joint is created as a ball and socket joint in which the ball is usually completely covered by the socket. In DDH the hip socket may be shallow so that it does not completely cover the ball, also known as the femoral head, allowing it to slip in and out of the socket. The "ball" may move partially or completely out of the hip socket.
The main risk factors for DDH are female sex, first-born children, a family history of a close relative with the condition, and being born in the breech position.
What causes DDH?
Hip dysplasia is considered a "multifactorial trait." Multifactorial inheritance means that many factors are involved in causing the problem. The factors are usually both genetic and environmental.
Often, one gender (either male or female) is affected more frequently than the other in multifactorial traits. There appears to be a different "threshold of expression," which means that 1 gender is more likely to show the problem than the other gender. For example, hip dysplasia is more common in females than males.
One of the environmental influences thought to contribute to hip dysplasia is the baby's response to the mother's hormones during pregnancy. A smaller uterus that prevents fetal movement or a breech delivery may also cause hip dysplasia. The left hip is involved more frequently than the right due to intrauterine positioning.
What are the risk factors for DDH?
First-born babies are at higher risk since the uterus is small and there is limited room for the baby to move; therefore affecting the development of the hip. Other risk factors include the following:
- Family history of developmental dysplasia of the hip
- Position of the baby in the uterus, especially breech presentations
- Associations with other orthopedic problems that include metatarsus adductus, clubfoot deformity, congenital conditions, and other syndromes
What are the signs and symptoms of DDH?
The following are the most common signs of DDH. However, each baby may experience symptoms differently. Signs may include:
- The leg may appear shorter on the side of the dislocated hip
- The leg on the side of the dislocated hip may turn outward
- The folds in the skin of the thigh or buttocks may appear uneven
- The space between the legs may look wider than normal
A baby with developmental dysplasia of the hip may have a hip that is partially or completely dislocated, meaning the ball of the femur slips partially or completely out of the hip socket. Most babies with DDH have no pain related to the hip. The symptoms of DDH may resemble other medical conditions of the hip. Always consult your baby's doctor for a diagnosis.
How is DDH diagnosed?
Developmental dysplasia of the hip is sometimes noted at birth. The pediatrician or newborn specialist screens newborn babies in the hospital for this hip problem with physical examination of the hips before they go home. However, DDH may not be discovered until later evaluations. Your baby's doctor makes the diagnosis of developmental dysplasia of the hip with a clinical examination. During the examination, the doctor obtains a complete prenatal and birth history of the baby and asks if other family members are known to have DDH.
Diagnostic procedures may include:
- X-ray (also called radiograph). A diagnostic test that uses invisible electromagnetic energy beams to produce images of internal tissues, bones, and organs.
- Ultrasound (also called sonography). A diagnostic imaging technique that uses high-frequency sound waves and a computer to create images of bone, cartilage, blood vessels, tissues, and organs.
Treatment for DDH
Specific treatment for DDH will be determined by your baby's doctor based on:
- Your baby's gestational age, overall health, and medical history
- The extent of the condition
- Your baby's tolerance for specific medications, procedures, or therapies
- Expectations for the course of the condition
- Your opinion or preference
The goal of treatment is to position the femoral head in the socket of the hip so that the hip can develop normally.
Treatment options vary for babies and may include:
- Nonsurgical positioning device
The Pavlik harness is used to treat babies up to 6 months of age. It holds the hips in place, while allowing the legs to move a little. The harness is put on by your baby's doctor and is usually worn for 12-24 hours per day for one to three months. Your baby is seen frequently during this time so that the harness may be checked for proper fit and to examine the hip. At the end of this treatment, X-rays or ultrasound are used to check hip position and development. The hip may be successfully treated with the Pavlik harness, but sometimes, it may continue to be partially or completely dislocated and may require further treatment. Other nonsurgical positioning devices that are commonly used include the rhino rigid abduction brace.
- Closed Reduction and Spica Casting
If the hip continues to be partially or completely dislocated, or if DDH is diagnosed between the ages of 6 months and 2 years, closed reduction and spica casting may be required. This is where the surgeon manually places the hip into a better position and holds it there in a cast. This is usually done in the operating room under general anesthesia. Your surgeon may inject dye into the hip joint to help better see the position of the hip joint. The cast usually remains in place full time for 6-12 weeks.
- Open Reduction Surgery
If the other methods are not successful, or if DDH is diagnosed after one to two years of age, surgery may be required to put the hip back into place, also known as a "open reduction." This includes surgically opening the hip joint and putting the ball in the socket. It may also include cutting and realigning the femur and pelvis bone. After this surgery, children are usually placed in a spica cast for 6-12 weeks.
Following casting, a special brace and/or physical therapy exercises may be necessary to make the muscles around the hip and in the legs stronger.
What is a short leg hip spica cast?
A short leg hip spica cast is applied from the chest to the thighs or knees. This type of cast is used to hold the hip in place after surgery to allow healing.
Cast care instructions
- Keep the cast clean and dry.
- Check for cracks or breaks in the cast.
- Rough edges can be padded to protect the skin from scratches.
- Do not scratch the skin under the cast by inserting objects inside the cast.
- Use a hairdryer placed on a cool setting to blow air under the cast and cool down the hot, itchy skin. Never blow warm or hot air into the cast.
- Do not put powders or lotion inside the cast.
- Cover the cast during feedings to prevent spills from entering the cast.
- Prevent small toys or objects from being put inside the cast.
- Elevate the cast above the level of the heart to decrease swelling.
- Do not use the abduction bar on the cast to lift or carry the baby.
When to call your baby's doctor
Contact your baby's doctor or other health care provider if your baby develops one or more of the following symptoms:
- Increased pain
- Increased swelling above or below the cast
- Drainage or foul odor from the cast
- Cool or cold toes
- A wet cast
Long-term outlook for a baby with DDH
While newborn screening for DDH allows for early detection of this hip condition, starting treatment immediately after birth may be successful. Many babies respond to the Pavlik harness, and/or casting. Additional surgeries may be necessary since the hip dislocation can reoccur as the child grows and develops. After successful treatment it is important to continue regular visits with the hip doctor. Xrays are taken on a regular basis until the child is finished growing. This is to make sure that the DDH does not reoccur. If left untreated, differences in leg length or abnormal walking, and a decrease in agility may occur. In children 2 years or older with DDH, deformity of the hip and osteoarthritis may develop later in life. DDH can also lead to pain and osteoarthritis by early adulthood if it is not treated.
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