Developmental Dysplasia of the Hip (DDH)
One in every 1,000 babies is born with DDH, a condition affecting the hip joint. The hip joint is a ball and socket joint, but children with DDH have a hip socket that is shallow, letting the ball of the long leg bone slip in and out of the socket. In mild cases, the ligaments and other soft tissues around the hip joint are slightly loose, causing the thighbone to move around more than normal in the hip socket. In more severe cases, the joint is so loose that the ball at the top of the thighbone can come partly out of the hip socket. Finally, dislocation is the most severe form when the ball fully slips out of the hip socket.
What causes DDH?
The exact cause is not known, but a number of factors can increase a child’s chance of having DDH including:
Being the first child
Low levels of amniotic fluid in the womb during pregnancy
Family history of the disorder
There may be no symptoms. Symptoms if they are present may include:
A baby with DDH may have:
A hip joint that feels loose or slips out of place when examined.
One leg that appears to be shorter than the other.
Extra folds of skin on the inside of one or both 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 off the floor because one leg is shorter than the other.
Walk with a limp.
How is it diagnosed?
The condition is typically diagnosed at birth or soon after at a well-baby checkup. It can become more difficult to diagnose the condition as a baby approaches three months because the only visible sign may be less mobility or flexibility of the hip joint. If the results of a physical exam are unclear, an ultrasound, X-ray, CAT scan, or MRI may be used to diagnose the condition.
Doctors treat DDH by moving the baby’s upper thighbone into the hip socket and keeping it in place while the joint grows. Treatment options include:
A Pavlik harness that is used on babies up to six months to keep the joint in place, while allowing the legs to move. It is usually worn full-time for at least six to eight weeks, then part-time (12 hours per day) for six weeks. Frequent check-ups are necessary to monitor progress.
A hard cast, known as a spica cast, is used for older babies if the hip continues to be partially or completely dislocated.
Surgery may be necessary if the other methods are unsuccessful or if DDH is diagnosed after a child is six months old. Children older than two may also need a spica cast after the surgery.
Illustration of infant wearing a Pavlik harness (http://www.lpch.org/diseaseHealthInfo/HealthLibrary/orthopaedics/ddh.html)
It is important to begin treatment as early as possible to address DDH. Fortunately, newborn screenings help with early detection. Many children respond successfully to the Pavlik harness and/or casting. However, hip dislocation can reoccur as the child grows and develops, potentially leading to a need for surgery. If left untreated, differences in leg length or a duck-like walk may result. In children two years or older, DDH can lead to deformity of the hip and osteoarthritis (a joint disorder) later in life.