Developmental Dysplasia of the Hip (DDH)

What is Developmental Dysplasia of the Hip (DDH)

Developmental dysplasia of the hip is a problem with formation of the hip joint that occurs during infancy. The hip joint is a ball and socket joint. The ball is the top of the thighbone (femur) which is called the femoral head.

The socket is called the acetabulum. The normal infant hip joint fits snugly, but the joint affected by DDH is loose. This can affect one hip or both hips.

There are several types of DDH. In one type, the socket is too flat, but the ball stays in the joint. In other cases, the ball slips out of the joint too easily. In more severe cases, the ball is outside the socket (the hip is dislocated). DDH may be found at birth during the baby’s newborn exam, or it may be found later. Early diagnosis and treatment will help avoid long term complications of DDH.

What are the causes?

The cause of this condition is not known.

What increases the risk?

Risk factors for developmental dysplasia of the hip (DDH)

• • Caucasian race.
• • Female gender.
• • Torticollis.
• • Clubfoot.
• • Breech birth.

Developmental dysplasia of the hip is more likely to develop in babies who:

• Are female.
• Are the first born.
• Have a family history of DDH.
• Were born with the buttocks or the feet first (breech birth).
• Have other disorders of the foot or leg, such as club foot.
• Were wrapped (swaddled) too tightly with the legs in a straight position.

What are the symptoms of developmental dysplasia of the hip?

Symptoms of this condition include:

• A fold on an infant’s thighs or buttocks that may appear uneven or lopsided.
• Decreased outward flexibility of the hip in older infants.
• Limp or unusual walk (gait) in older children.
• Legs that are different lengths.

When is developmental dysplasia of the hip suspected clinically?

It is difficult to diagnose DDH in newborns 4 weeks old or younger because of normal joint laxity, but this condition is suspected in infants with leg length discrepancy and asymmetric thigh creases.

The Barlow maneuver on physical examination dislocates the femoral head rearward when DDH is present, and the Ortolani maneuver reduces the recently dislocated hip, often with a resultant “clunk.”

How is developmental dysplasia of the hip diagnosed?

Developmental dysplasia of the hip may be diagnosed based on:

• A physical exam.
• An ultrasound of the hip to confirm diagnosis.
• Hip X-rays. This is done on older infants and children.
• Other kinds of imaging tests, such as:
  • MRI.
  • CT scan.

How is developmental dysplasia of the hip diagnosed radiographically?

Traditionally, radiography has been used to diagnose DDH. Although the femoral head begins to ossify during the first year (usually between 3 to 6 months), its location must be inferred in infants.

The acetabulum is divided into quadrants by the horizontal Hilgenreiner line, drawn through both triradiate cartilages, and the vertical Perkin line, drawn through the lateral rim of the acetabulum.

A normal femoral head should fall within the inner lower quadrant of these intersecting lines, whereas a femoral head in DDH would be displaced superolaterally.

The acetabular angle should also be evaluated, drawn between Hilgenreiner line and a line connecting the superolateral ridge of the acetabulum with the triradiate cartilage. This angle should be less than 30 degrees in neonates.

How is developmental dysplasia of the hip diagnosed on ultrasonography (US)?

US is now the preferred method of diagnosing DDH in children younger than 1 year old.

The hip is studied in the coronal plane. The alpha angle is measured between the straight lateral margin of the ilium and a line from the inferior point of the ilium tangential to the acetabulum.

This is a measure of acetabular depth and should be greater than 60 degrees. At least half of the femoral head should be seated within the acetabulum.

How is developmental dysplasia of the hip treated?

Treatment for this condition depends on your child’s age and the response to previous treatments, if any. Treatment includes:

• Wearing a Pavlik harness for 1–2 months. This is a soft brace that has straps that fasten around the chest and the legs. The straps hold the legs in the proper position to hold the femoral head in the socket. This helps the socket form properly.
• Surgery. There are two procedures that may be used to treat this condition:
  • Closed surgical reduction. During this surgery, the femur is moved in order to position the femoral head correctly.
  • Open reduction. This procedure is used if closed surgical reduction does not work. During this procedure, the femoral head is moved to the correct position and the socket is shaped.
• Wearing a cast that holds the hips and legs in place (spica cast) after either type of reduction.

Potential complications of untreated developmental dysplasia of the hip

• • Leg length discrepancy.
• • Osteoarthritis.
• • Pain.
• • Gait disturbance.
• • Decrease in agility.

Summary

• Developmental dysplasia of the hip (DDH) is a problem with formation of the hip joint that occurs during infancy. The normal infant hip joint fits snugly, but the joint affected by DDH is loose.
• DDH is most common in female, first-born infants that are born in the breech position.
• Once your child is diagnosed with DDH, it is important that the hip is placed back in proper location by a healthcare provider and allowed to heal.
• Early diagnosis and treatment will help avoid long term complications of DDH.