What is DDH?
Developmental dysplasia of the hip is a congenital (present at birth) condition of the hip joint. It occurs once in every 1,000 live births. The hip joint is created as a ball and socket joint. In DDH, the hip socket may be shallow, letting the "ball" of the long leg bone, also known as the femoral head, slip in and out of the socket. The "ball" may move partially or completely out of the hip socket.
The greatest incidence of DDH occurs in first-born females with a history of a close relative with the condition.
What causes DDH?
Hip dysplasia is considered a "multifactorial trait." Multifactorial inheritance means that many factors are involved in causing a birth defect. 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 one 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 tight 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 may include the following:
Family history of developmental dysplasia of the hip, or very flexible ligaments
Position of the baby in the uterus, especially with breech presentations
Associations with other orthopedic problems that include metatarsus adductus, clubfoot deformity, congenital conditions, and other syndromes
What are the symptoms of DDH?
The following are the most common symptoms of DDH. However, each baby may experience symptoms differently. Symptoms 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. 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 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. A diagnostic test which uses invisible electromagnetic energy beams to produce images of internal tissues, bones, and organs onto film.
Ultrasound (also called sonography). A diagnostic imaging technique which uses high-frequency sound waves and a computer to create images of blood vessels, tissues, and organs. Ultrasounds are used to view internal organs as they function, and to assess blood flow through various vessels.
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 put the femoral head back into the socket of the hip so that the hip can develop normally.