Hip Dysplasia

What is hip dysplasia?

Hip dysplasia is the medical name used to describe a problem with formation of the hip joint in children. The location of the problem can be either the ball of the hip joint (femoral head), the socket of the hip joint (the acetabulum), or both.

Historically, many doctors have called the problem congenital dysplasia of the hip, or CDH. More recently, the accepted terminology is developmental dysplasia of the hip, or DDH.

What causes hip dysplasia?
The exact cause of hip dysplasia is not easy to pin down, as there are thought to be several factors that contribute to developing this condition. Hip dysplasia occurs in about 0.4% of all births, and is most common in first born girls. Some known risk factors for a child to have hip dysplasia include:

• Children with a family history of hip dysplasia
• Babies born in breech position
• Babies born with other "packaging problems"*
• Oligohydraminos (lack of intrauterine fluid)
*Packaging problems are conditions that result in part from the in-utero position of the baby; for example, clubfoot and torticollis.

How is hip dysplasia diagnosed?
Diagnosis of hip dysplasia in the infant is based on the physical examination findings. Your doctor will feel for a "hip click" when performing special maneuvers of the hip joint. These maneuvers, called the Barlow and Ortolani tests, will cause a hip that is out of position to "click" as it moves in and out of the proper position.

If a hip click is felt, your doctor will usually obtain a hip ultrasound to assess the hip joint. An x-ray does not show the bones in a young baby until at least 6 months of age, and therefore a hip ultrasound is preferred. The hip ultrasound will show the doctor the position and shape of the hip joint. Instead of the normal ball-in-socket joint, the ultrasound may show the ball outside of the socket, and a poorly formed (shallow) socket. The hip ultrasound can also be used to determine how well the treatment is working.

What is the treatment of hip dysplasia?
The treatment of hip dysplasia depends on the age of the child. The goal of treatment is to properly position the hip joint ("reduce" the hip). Once an adequate reduction is obtained, the doctor will hold the hip in that reduced position and allow the body to adapt to the new position. The younger the child, the better capacity to adapt the hip, and the better chance of full recovery. Over time, the body becomes less accommodating to repositioning of the hip joint. While treatment of hip dysplasia varies for each individual baby, a general outline follows:

• Birth to 6 months
  Generally in newborns, a hip dysplasia will reduce with the use of a special brace called a Pavlik harness. This brace holds the baby's hips in a position that keeps the joint reduced. Over time, the body adapts to the correct position, and the hip joint begins normal formation. About 90% of newborns with hip dysplasia treated in a Pavlik harness will recover fully. Many doctors will not initiate Pavlik harness treatment for several weeks after birth.

• 6 months to 1 year
  In older babies, Pavlik harness treatment may not be successful. In this case, your orthopedic surgeon will place the child under general anesthesia. This usually allows the hip to assume the proper position. Once in this position, the child will be placed in a spica cast. The cast is similar to the Pavlik harness, but allows less movement. This is needed in older children to better maintain position of the hip joint.

• Over age 1 year
  Children older than one year old often need surgery to reduce the hip joint into proper position. The body can form scar tissue that prevents the hip from assuming its proper position, and surgery is needed to properly position the hip joint. Once this is done, the child will have a spica cast to hold the hip in the proper position.

The success of treatment depends on the age of the child, and the adequacy of the reduction. In a newborn infant with a good reduction, there is a very good chance of full recovery. When treatment begins at older ages, the chance of full recovery decreases. Children who have persistent hip dysplasia have a chance of developing pain and early hip arthritis later in life. Surgery to cut and realign the bones (hip osteotomy), or a hip replacement, may be needed later in life.

_Sources:

Guille JT, Pizzutillo PD, MacEwen GD "Developmental Dysplasia of the Hip From Birth to Six Months" J. Am. Acad. Ortho. Surg., July/August 2000; 8: 232 - 242.

Vitale MG and Skaggs DL "Developmental Dysplasia of the Hip From Six Months to Four Years of Age" J. Am. Acad. Ortho. Surg., November/December 2001; 9: 401 - 411.