What is Developmental Dysplasia of the Hip (DDH)?
Developmental dysplasia of the hip, or DDH, is a term that refers to instability of newborn hips. This occurs when the hip joint does not develop normally.
This condition often appears during infancy but may develop later in childhood. If the child’s symptoms are mild, it can go unnoticed during infancy and childhood. If left untreated, it might resolve on its own, or in some cases worsen, causing hip pain later in life. When this occurs, we refer to the condition as adolescent hip dysplasia.
Causes of DDH
The exact causes of DDH are not always known. Hip instability might appear after birth in babies who were in the breech position for an extended period of time before delivery. In some cases, that can lead to hip dysplasia.
Improper swaddling may also contribute to DDH when an infant’s legs are swaddled in a straight, close position. The International Hip Dysplasia Institute demonstrates how to properly swaddle an infant, which can reduce the risk of developing dysplasia.
DDH can occur in otherwise healthy children, or it can be associated with specific conditions or syndromes including:
- Neuromuscular diseases such as cerebral palsy
- Hyperlaxity, commonly seen in Ehlers Danlos and Marfan syndromes
- Skeletal dysplasia, a grouping of disorders that affect how children’s bones grow
Signs and Symptoms of DDH
Signs of developmental dysplasia of the hip can often be detected during a physical exam. They can vary from mild to severe. Your doctor may be able to feel the ball of the hip going in and out. Other symptoms you might notice can include:
- A difference in leg lengths; this might not be noticed until your child starts to walk
- A limp in a child old enough to walk; it is painless to the child and likely doesn’t cause complaints from the child
- One leg might not spread as much as the other; you might notice this during diaper changes in young children
How Common Is DDH?
Development dysplasia of the hip is a common condition, occurring in about one in every 1,000 newborns.
Infants and children who are more likely to have DDH are:
- First-born children
- Those who have a parent or sibling with DDH
- Babies born in the frank breech position, with their feet up by the ears
Diagnosis of DDH
Doctors will perform a physical exam to diagnose developmental dysplasia of the hip. The hips of infants with DDH are unstable. They may pop in and out of the socket with movement, or may be very loose on examination. To confirm the diagnosis and rule out other conditions, the following imaging methods may also be used:
- Ultrasound, for infants
- X-ray, for children starting at about 4-6 months of age
- MRI (magnetic resonance imaging), more often for teenagers and young adults
- CT (computed tomography) scan
Treatment of DDH
Treatment varies depending on how severe the hip dysplasia is. The care team at Cincinnati Children’s tailors treatment to each patient.
In mild cases, the first line of treatment is often close observation. In these cases, the doctors work closely with the parents to watch for signs of progression with the hope that the condition will resolve on its own.
In situations when the dysplasia becomes more serious and observation is not enough, treatment options may include:
If the hip dislocation is moderate, treatment often consists of a Velcro harness from the chest down to the legs. This is called a Pavlik harness (named for the physician who developed it). It keeps the hips in a frog-like position, with the hips spread out and knees bent.
Your baby will need to remain in the harness for six to 12 weeks. During that time, we monitor your child’s progress with physical exams and ultrasounds. This treatment is effective in about 90 percent of babies with DDH. It can be used on children up to 6-9 months of age.
Those babies whose hips do not improve with the Pavlik harness may need a different kind of brace such as the Rhino brace or Ilfeld brace. In many cases, the child may need surgery.
Closed reduction is a surgery where the child’s hip is repositioned into the socket. Often other procedures may be done at the same time, such as a tendon release, where the tendon is cut to allow the hip to spread more easily. After the surgery, your child will be put into a hip spica cast for at least three months to allow the hip to properly heal.
If a closed reduction doesn’t work, an open reduction may be needed. This is a more invasive surgery used in more severe cases of hip dysplasia. Open reductions are usually performed when a child is over 1 year old. In this surgery, an incision will be made in the front of the hip to open the hip joint. The surgeon will remove tissue from the hip joint so that the ball of the hip will fit into the socket better. Bones of the pelvis and the femur may also need to be cut and repositioned to keep the ball in the socket better. As with a closed reduction, your child will be put into a hip spica cast after surgery for three months. Often a child will then need a hip abduction brace (also called a Rhino brace) to finish the healing process.
With all of these treatments, children usually don’t require rehabilitation afterward.
In general, the earlier a child is treated for hip dysplasia, the less work the hip needs later in life.
For children who use a Pavlik harness or undergo a successful closed reduction, most of the time no other treatments are needed afterward. In a small number of patients, more surgery may be needed later in childhood or into adolescence.
For children who need an open reduction, their hips are never quite normal. They may notice problems with their hips as they grow. Chances are higher that these children may need a total hip replacement when they’re older.
If DDH is left untreated, it can lead to pain and arthritis in early adulthood. Even those who have treatment sometimes have hip deformity and arthritis later in life.