Hip dysplasia

Medical quality assurance by Dr. Albrecht Nonnenmacher, MD at April 14, 2016
StartDiseasesHip dysplasia

Hip dysplasia is a condition in which the hip socket does not fully cover the ball of the upper thighbone, called the femur. Because the joint does not fit together securely, the hip can become either fully or partially dislocated. The condition is sometimes referred to as developmental dysplasia of the hip (DDH), congenital dislocation of the hip, hip dislocation, or loose hips.

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Definition & Facts

In a normal hip, the ball of the femur fits into a cup-shaped socket in the pelvis called the acetabulum. The ball and socket are held in place by various tendons, ligaments, and muscles. In individuals with hip dysplasia, the acetabulum may be too shallow, or the supporting tissues may be too loose. This allows the femoral head to slip partially or fully out of the socket.

Hip dysplasia affects thousands of children and adults. Approximately two to three out of every 1,000 babies are born with DDH. The condition is typically present at birth but can also be found in adolescents and adults with no prior history of hip problems.

Symptoms & Complaints

In young children, DDH typically does not cause pain. In infants, the parents may notice that one leg appears shorter than the other, that there are extra skin folds on the inside of one thigh, or that one hip joint seems to move differently than the other. Once the child starts walking, the parents may notice that the child walks with a limp or walks on the toes of one foot.

If hip dysplasia continues into adolescence or adulthood, the individual will typically start to experience pain that worsens over time. Common symptoms of hip dysplasia in teens and adults include:

  • An abnormal gait, including limping or waddling.
  • Legs are turned or positioned abnormally.
  • One leg may appear shorter than the other.
  • Decreased range of motion in the hip joint that is partially or fully dislocated.

Causes

A baby’s hip joint is made up of soft cartilage. Over time, this cartilage hardens into bone. The ball and socket essentially serve as molds for each other, so they must fit together securely. In some instances, crowding in the womb can force the femoral head out of position, which causes the socket to be much shallower than normal. This typically occurs during the final month of pregnancy. Womb overcrowding is most common during first pregnancies, when the baby is particularly large, or when the baby presents in a breech position.

Hip dysplasia often runs in families and is more prevalent among females. Swaddling an infant too tightly can also lead to hip dysplasia. If parents suspect their child has hip dysplasia, it is important to seek diagnosis and treatment as early as possible to reduce the risk of long-term hip problems, such as arthritis. In adults, hip dysplasia is normally the result of the hip developing abnormally during the growing years; however, the reason for the abnormal development is not known.

Diagnosis & Tests

Most cases of hip dysplasia are diagnosed during newborn physical examinations or well-child checks. The doctor will move the child’s legs to check for flexibility and range of motion in the hip joints. These checks should continue throughout infancy. If the physician suspects DDH, they will likely order imaging tests, such as an X-ray to verify the alignment of the hip joint. MRIs may be used to assess the cartilage of the hip joint.

If DDH is diagnosed during infancy, it can usually be corrected with bracing. After age two, surgery may be necessary to ensure proper joint movement. According to the International Hip Dysplasia Institute, many cases of hip dysplasia are difficult to diagnose using current methodologies. A study conducted in Norway in 2008 estimated that as many as 90 percent of hip dysplasia cases in young adults could not be detected using traditional screening methods. The IHDI is currently conducting research into new approaches for the early detection and prevention of hip dysplasia.

Treatment & Therapy

The treatment of hip dysplasia is determined by the age of the patient and the severity of the hip damage. In very young infants, a soft brace called a Pavlik harness can be used for several months. The harness is designed to hold the femoral head in place so that the socket can mold properly to the shape of the ball. A Pavlik harness typically does not work well for infants older than six months. In this case, the doctor may use a full body cast to hold the bones into position for several months. Children over two and adults typically require surgery to correct the dysplasia. The following are the most frequently used surgical treatments to correct hip dysplasia:

  • Hip arthroscopy—In this procedure, a camera is inserted into the body to allow the doctor to view and correct minor damage to the hip cartilage. Arthroscopy is often used in conjunction with osteotomy.
  • Periacetabular osteotomy—During this procedure, the acetabulum is separated from the pelvis and repositioned into its proper alignment with the femoral head. Screws are used to ensure that the socket remains in the correct position.
  • Femoral osteotomy—This is a less common procedure in which the femur is realigned into the acetabulum and fitted with a plate and screws to hold it in position.
  • Hip replacement—Adults with severe hip dysplasia may have to replace the hip joint with a prosthetic joint.

Prevention & Prophylaxis

Since most hip dysplasia develops in infancy, parents should be aware of steps they can take to ensure their child’s hips develop properly.

  • Parents should make sure they schedule all well-child appointments as recommended by their pediatrician. They should ensure that the doctor checks hip function at all appointments.
  • Parents should make their physician aware of any family history or issues surrounding the child’s birth that could increase the risk of hip dysplasia.
  • When swaddling a baby, parents should ensure that the legs are still able to bend up and out at the hips. The baby should not be wrapped so tightly that the legs are pressed together and straight down.