Developmental Dysplasia of the Hip
Developmental dysplasia of the hip (DDH) is a broad term used to describe a variety of hip abnormalities that can develop in utero or sometimes even after birth. DDH can range from a misshapen hip ball or socket to a complete dislocation of the hip.
DDH occurs in one in every 1,000 births. More common in females, it is usually caused by genetic and environmental factors. One of the environmental factors may be the baby's response to the mother's hormones during pregnancy. A tight uterus that limits fetal movement or a breech position is also associated with DDH. DDH is more likely to occur in the left hip.
First-born babies are at higher risk because the uterus is small and there is limited room for the baby to move, affecting the development of the hip. Other risk factors may include:
- Family history of DDH, or very flexible ligaments
- Position of the baby in the uterus, especially with breech presentations
- Associations with other orthopaedic problems that include metatarsus adductus, clubfoot deformity, congenital conditions and other syndromes
With DDH, the hip socket (acetabulum) may be shallow. This can allow the ball (femoral head) of the leg bone to slip in and out of the hip socket. The ball may move partially or completely out of the socket. But symptoms can vary by age of the child.
- Signs of DDH in babies, infants and toddlers include:
- Leg may appear shorter on the side of the affected hip
- The rotation of the affected hip may be different
- Folds in the skin of the thigh or buttocks may appear uneven
- Space between the legs may look wider than normal
- The hip may shift, click or clunk during certain movements, such as diaper changes
- Signs of DDH in adolescents, teens and young adults include:
- Hip pain
- Clicking sound in the hip joint
- Catching feeling in hip joint
- Limited or excessive movement of the hip
- Difference in limb length
Your doctor will do a physical exam of your child at birth and during infancy to check for DDH and other hip problems. Signs may not show until later in life. Diagnostic procedures may include X-rays, ultrasound, CT scans or MRIs.
The course of treatment will depend on your child’s age, medical history, extent of DDH and tolerance for treatment. The main goal is to reposition the ball back into the hip socket to allow for stabilization and normal development. Unfortunately, some hips do not continue to develop normally even after they stabilize. Further treatment is sometimes required.
In general, babies up to six months of age are treated with the Pavlik harness that guides the hip into place but still allows some movement of the legs. The doctor applies the harness to the baby and the harness is worn full time for at least six weeks. During this time, the baby will see the doctor to check for proper fit and to examine the hip by using X-rays or ultrasounds. Once the images are normal, the harness is removed.
If the harness is not successful or DDH is diagnosed after six months of age, a closed reduction surgery may be necessary to put the hip back into place manually. This procedure is sometimes combined with procedures called an arthrogram and an adductor tenotomy, which are used to help assess the reduction and increase hip stability and flexibility.
If the closed reduction surgery is successful in putting the hip back into its proper place, a special cast called a spica cast (link to spica cast page) is used to hold the hip in place. Usually, the spica cast is worn for three to six months and is changed periodically to keep up with your child’s growth. After the spica cast is removed, a brace and physical therapy may be needed to strengthen the muscles around the hip.
Children with DDH who have reached or have almost reached their maximum skeletal growth might need a periacetabular osteotomy (PAO) procedure to reduce joint stress and improve hip function. This procedure allows the surgeon to make cuts around the hip sock to move it back into a more normal position. A PAO can also help delay or eliminate the need for total hip replacement later in life.