What Is It?
In a normal hip joint, the rounded top of the thigh bone (femur) fits into a cup-shaped socket in the pelvis called the acetabulum. This type of joint is called a ball-and-socket joint. In developmental dysplasia (dis-PLAY-shah) of the hip, the hip joint is unstable, and the top of the femur moves in and out of the socket either partially or completely. In some cases, the top of the femur is dislocated — displaced completely from its normal position in the socket.
This condition is present at birth and can be related to birth.
Developmental dysplasia of the hip probably is caused by a combination of inborn factors and birth-related stress. For example, many babies with this condition are born with unusually loose or lax hip ligaments, the fibrous tissues that strap the femur into its socket. These loose ligaments allow the femur to move too much within the hip joint, making the hip unstable and prone to dislocation. This risk of dislocation seems to be highest during birth, when the squeezing pressure of a vaginal delivery stresses a baby’s hips. Children who are delivered in the breech position (buttocks first) are particularly vulnerable, especially if their hips are sharply flexed during passage through the birth canal.
In the United States, this type of hip problem causes hip dislocations in about one out of every 1,000 newborns. The condition is much more common in girls than in boys, between 80 percent to 90 percent. The risk of developmental dysplasia of the hip is higher in firstborns, and about 40 percent of babies with the condition were delivered in the breech position.
Developmental dysplasia of the hip is a serious condition that must be diagnosed and treated early. Unless the baby’s hip is replaced in its socket and its supporting ligaments are strengthened appropriately, the child can develop a variety of long-term orthopedic problems, including chronic hip pain, arthritis at a young age, a shortened leg on the affected side, and difficulty walking.
In an infant, developmental dysplasia of the hip can cause the following symptoms:
- One leg is shorter than the other.
- The right and left kneecaps are at different levels when the legs are compared side to side.
- One thigh has a different number of skin folds than the other or a different pattern of skin folds.
- One leg moves less than the other or seems to be less flexible.
Doctors routinely check for symptoms of developmental dysplasia of the hip during the first physical exam of a newborn (within a day or two of birth) and also at follow-up well-baby visits. As part of the normal screening for this condition, your doctor will want to know whether your child was delivered in the breech position, is a firstborn, or has a parent or sibling who had the problem.
During your baby’s physical examination, your doctor checks for developmental hip dysplasia by gently moving the baby’s legs while supporting and checking for movement in his or her hips. One of these maneuvers, called the Barlow test, identifies an unstable hip that dislocates easily. The other maneuver, called the Ortolani test, slips a dislocated hip back into its socket. If the doctor feels enough movement of the hip to suggest that your child has a hip dislocation, he or she will confirm the diagnosis by ordering either an ultrasound or standard X-rays of your child’s hip. Ultrasound is used in newborns and very young infants, because certain parts of the hip bones cannot be seen clearly on X-rays until a child is 3 months to 7 months old. In difficult cases, especially in older children with developmental dysplasia of the hip, the doctor may need to order a computed tomography (CT) scan, magnetic resonance imaging (MRI) scan or arthrogram, tests that can show greater detail of the hip anatomy. In an arthrogram, X-rays are taken after dye is injected into the hip joint.
Treatment lasts until the hip joint becomes stable and the child’s ultrasound or X-ray studies are normal. This usually takes one to two months if the baby’s dislocation was identified immediately after birth.
In many cases, it is hard to prevent a hip dislocation. To identify infants with developmental hip dysplasia as soon as possible, some experts recommend ultrasound screening for all female babies born in the breech position.
Treatment of developmental dysplasia of the hip depends on the child’s age:
- Newborns — Newborn babies usually wear a special orthopedic device, such as the Pavlik harness or the Frejka splint, to hold the affected hip in position. After about one to two months of treatment, the hip ligaments gradually tighten and the hip joint usually stabilizes.
- Infants age 1 month to 6 months — As in newborns, the doctor will begin treatment with a harness or splint. If these devices are not effective, the doctor will gently reposition the head of the femur while the child is under anesthesia. This procedure is called a closed reduction. Once the femur is back in place, the child will wear a body cast, called a spica cast, until X-rays show that the hip joint is normal.
- Children age 6 months to 18 months — Most children can be treated with closed reduction and a spica cast, although some require open surgery to correct the hip problem.
- Children older than 18 months — These children are treated with open surgery followed by a spica cast. In most cases, the spica cast can be removed after six to eight weeks. Then the child is allowed to return gradually to normal physical activities.
When To Call A Professional
Doctors routinely check for developmental hip dysplasia during well-baby visits. However, if you notice that your baby has trouble moving one leg, or that one of your baby’s legs seems to be shorter than the other, call your doctor to discuss the problem.
If the hip problem is identified and treated early, the child should walk normally and have normal hip function.
Diseases and Conditions Center
All ArmMed Media material is provided for information only and is neither advice nor a substitute for proper medical care. Consult a qualified healthcare professional who understands your particular history for individual concerns.