Congenital Hip Dysplasia

Congenital hip dysplasia

Definition

Congenital hip dysplasia is a condition of abnormal development of the hip, resulting in hip joint instability and potential dislocation of the thigh bone from the socket in the pelvis. This condition has been in the early 2000s been termed developmental hip dysplasia, because it often develops over the first few weeks, months, or years of life.

Description

Congenital hip dysplasia is a disorder in children that is either present at birth or shortly thereafter. During gestation, the infant's hip should be developing with the head of the thigh bone (femur) sitting perfectly centered in its shallow socket (acetabulum). The acetabulum should cover the head of the femur as if it were a ball sitting inside of a cup. In the event of congenital hip dysplasia, the development of the acetabulum in an infant allows the femoral head to ride upward out of the joint socket, especially when the infant begins to walk.

Demographics

In the United States, approximately 1.5 percent of all infants have congenital hip dysplasia. Though the worldwide incidence of congenital hip dysplasia varies, researchers estimate the global incidence to be approximately 1 percent.

Clinical studies show a familial tendency toward hip dysplasia with a greater chance of this hip abnormality in the first born compared to the second or third child. Infants with siblings who have been diagnosed with congenital hip dysplasia or who have parents with the defect are at an increased risk. Females are affected four to eight times more than males, and in children with congenital hip dysplasia, the left leg in more often affected. This disorder is found in many cultures around the world. However, statistics show that infants in colder climates have a higher incidence. It is speculated that this increase may be due to the practice of swaddling which can place the infant's legs in an extreme straightened or adducted position, forcing the hips closer together. The incidence of congenital hip dysplasia is also higher in infants born by cesarean and in breech position births.

Causes and symptoms

Hormonal changes within the mother during pregnancy result in increased ligament looseness or laxity and are thought to possibly cross over the placenta and cause the baby to have lax ligaments while still in the womb. Other symptoms of complete dislocation include a shortening of the leg and limited ability to abduct the leg, or move it outward.

Diagnosis

Because the abnormalities of this hip problem often vary, a thorough physical examination is necessary for an accurate diagnosis of congenital hip dysplasia. The hip disorder can be diagnosed by moving the hip to determine if the head of the femur is moving in and out of the hip joint. One specific method, called the Ortolani test, begins with each of the examiner's hands around the infant's knees, with the second and third fingers pointing down the child's thigh. With the legs abducted (moved apart), the examiner may be able to hear a distinct clicking sound, called a hip click, with motion. If symptoms are present with a noted increase in abduction, the test is considered positive for hip joint instability. It is important to note this test is only valid a few weeks after birth.

The Barlow method is another test performed with the infant's hip brought together with knees in full bent position. The examiner's middle finger is placed over the outside of the hipbone while the thumb is placed on the inner side of the knee. The hip is abducted to where it can be felt if the hip is sliding out and then back in the joint. In older babies, if there is a lack of range of motion in one hip or even both hips, it is possible that the movement is blocked because the hip has dislocated and the muscles have contracted in that position. Also in older infants, hip dislocation may be present if one leg looks shorter than the other.

X-ray films can be helpful in detecting abnormal findings of the hip joint. X rays may also be helpful in finding the proper positioning of the hip joint for treatment. Ultrasound has been noted as a safe and effective tool for the diagnosis of congenital hip dysplasia. Ultrasound has advantages over x rays, as several positions are noted during the ultrasound procedure. This is in contrast to only one position observed during the x ray.

Treatment

The objective of treatment is to replace the head of the femur into the acetabulum and, by applying constant pressure, to enlarge and deepen the socket. In the past, stabilization was achieved by placing rolled cotton diapers or a pillow between the thighs. The child may be dressed in two or three diapers, called double or triple diapering. Both these techniques keep the knees in a frog-like position. In the early 2000s, the Pavlik harness and von Rosen splint are commonly used in infants up to the age of six months to spread the legs apart and force the head of the femur into the acetabulum. A stiff shell cast, called a splint, may be also used to achieve the same purpose. In some cases, older children between six to 18 months old may need surgery to reposition the joint. Also at this age, the use of closed manipulation may be applied successfully, by moving the leg around manually to replace the joint. Operations are performed to reduce the dislocation of the hip and to repair a defect in the acetabulum. A cast is applied after the operation to hold the head of the femur in the correct position. As of 2004 the use of a home traction program was more common. However, after the child is eight years of age, surgical procedures are primarily done for pain reduction measures only. Total hip surgeries may be inevitable later in adulthood.

Alternative treatment

Nonsurgical treatments include exercise programs, orthosis (a force system, often involving braces), and medications. A physical therapist may develop a program that includes strengthening, range-of-motion exercises, pain control, and functional activities. Chiropractic medicine may be helpful, especially the procedures of closed manipulations, to reduce the dislocated hip joint.

Prognosis

Unless corrected soon after birth, congenital hip dysplasia can cause a characteristic limp or waddling gait in children. If left untreated, the child will have difficulty walking and may experience life-long pain. If diagnosed early, congenital hip dysplasia treatment is highly effective. Children who have received casting, bracing, or surgery, usually go on to have normal hip and leg development. In individuals for whom the diagnosis is made later, the prognosis is not as positive. These children may require more extensive surgery. After surgery, however, the prognosis for normal development of the hip and leg is excellent.

Prevention

Prevention includes proper prenatal care to determine the position of the baby in the womb. This may be helpful in preparing for possible breech births associated with hip problems. Avoiding excessive and prolonged infant hip adduction, or forcing the legs in a straight position close together for periods of time (as in swaddling) may help prevent strain on the hip joints. Early diagnosis remains an important part of prevention of congenital hip dysplasia.

Parental concerns

It is important for infants suspected of having congenital hip dysplasia to receive regular physical examinations. Since this disorder of the hip is progressive and early detection and treatment are essential, the American Academy of Pediatrics has suggested guidelines for examination and treatment of children suspected of having development hip dysplasia. They suggest referral to a pediatric orthopedist if an infant has a positive Ortolani or Barlow test. For infants with mild hip clicks, they suggest the child be seen by the regular pediatrician in two weeks for follow up since most benign hip clicks will resolve within that time period. If signs of hip dysplasia are still present after two weeks, it is recommended that the child be seen by a pediatric orthopedist. If double or triple diapering is recommended by the pediatrician after the initial newborn exam, it is imperative that parents follow up with their pediatrician for a more extensive examination of the hips soon after the newborn comes home.

KEY TERMS

Abduction —Turning away from the body.

Acetabulum —The large cup-shaped cavity at the junction of pelvis and femur (thigh bone).

Adduction —Movement toward the body.

Bracing —Using orthopedic devices to hold joints or limbs in place.

Dislocation —The displacement of bones at a joint or the displacement of any part of the body from its normal position.

Dysplasia —Abnormal changes in cells.

Femur —The thigh bone.

Orthosis —An external device, such as a splint or a brace, that prevents or assists movement.

Placenta —The organ that provides oxygen and nutrition from the mother to the unborn baby during pregnancy. The placenta is attached to the wall of the uterus and leads to the unborn baby via the umbilical cord.

Splint —A thin piece of rigid or flexible material that is used to restrain, support, or immobilize a part of the body while healing takes place.

Resources

BOOKS

Rudolph, Colin D., and Abraham M. Rudolph, eds. Rudolph's Pediatrics, 21st ed. New York: McGraw-Hill, 2003.

ORGANIZATIONS

March of Dimes Birth Defects Foundation. 1275 Mamaroneck Ave., White Plains, NY 10605. Web site: <www.modimes.org>.

WEB SITES

American Academy of Pediatrics, Committee on Quality Improvement, Subcommittee on Developmental Dysplasia of the Hip. "Clinical Practice Guideline: Early Detection of Developmental Dysplasia of the Hip (AC0001)." Pediatrics 105, no. 4 (April 2000): 896–905. Available online at <www.aap.org/policy/ac0001.htm> (accessed December 8, 2004).

Norton, Karen I., and Sandra A. Mitre. "Developmental Dysplasia of the Hip." eMedicine, April 22, 2003. Available online at <www.emedicine.com/radio/topic212.htm> (accessed December 8, 2004).

Jeffrey P. Larson, RPT Deborah L. Nurmi, MS