Everything You Need to Know About Developmental Dysplasia of the Hip (DDH)

Developmental dysplasia of the hip (DDH), a fairly common disorder of the developing hip joint, occurs in about 1 in every 1,000 live births. The hip joint is formed by a rounded femoral head fitting into a cup-shaped socket called the acetabulum. In DDH, the hip joint can be unstable, causing the ball to move partially or completely out of the socket.

Additionally, the hip socket is often shallow, which can raise the risk of arthritis and joint pain as the person grows older. Hip dysplasia can vary in severity, from a slightly shallow hip socket to a fully dislocated hip joint.

DDH is most common in first-born girls, especially if they have a close family member with the condition or were in a breech position before birth.

Causes

The precise cause of hip dysplasia is not yet known. However, it is likely that many factors, such as environmental and genetic causes, play a role.

First-born babies are at greater risk because the limited space in the uterus can restrict movement, impacting hip development. Additional risk factors can include:

Other risk factors may include a family history of developmental dysplasia of the hip or unusually flexible ligaments. The baby’s position in the uterus, particularly breech presentation, can also increase the risk. Hip dysplasia may be associated with other orthopedic conditions such as metatarsus adductus, clubfoot, congenital disorders, and certain syndromes. Frequent swaddling with the hips kept straight (extended) can further contribute to the risk.

Risk factors of DDH

Owing to the small size of the uterus, the foetus does not have enough space to move around, hence leading to a higher risk of DDH.

Other factors may include:

• Family history of DDH, or extremely flexible ligaments
• Foetal position, especially with breech presentation
• Hip dysplasia may be linked to other orthopedic issues, including metatarsus adductus, clubfoot, congenital disorders, and various syndromes.
• Frequent swaddling with the hips extended (out straight)

Symptoms

In newborns, the symptoms of hip dysplasia are often very subtle. Although typically painless in infancy and early childhood, the condition can cause pain and functional problems later in life if not treated. Characteristic findings that raise a suspicion for DDH include: Symptoms:

• The leg on the affected side may seem shorter due to the dislocated hip.
• The affected leg does not spread as widely as the normal side
• The skin folds on the thigh or buttocks may look uneven.
• ‘Clunk’ felt with diaper changes or other positions of the leg
• Depending on the severity, the child may have a limp or ‘waddle’ while walking or running
• During adolescence, pain and differences in leg length may develop.
• A remaining shallow hip socket is believed to be the main factor leading to arthritis.

Diagnosis

DDH is sometimes noted at birth when the paediatrician or the newborn specialist screens newborn babies at the hospital. Your baby’s physician may make the diagnosis with a clinical examination. The doctor takes a detailed prenatal and birth history of the baby and asks about any family history of DDH. However, DDH may not be discovered until later stages of evaluation and can not be diagnosed with just a physical examination.

Diagnostic Procedures:

• Ultrasound (also called Sonography) – High-frequency sound waves and computer technology are used in this method to generate images of the baby’s hip joint. This uses no radiation and is best for younger infants for whom the hip joint is still made of cartilage.
• X-Ray – It uses invisible electromagnetic beams to create images of the hip joint. This is the primary test for diagnosing or tracking DDH in infants older than six months.
• Computed Tomography scan (CT scan) – This method uses X-rays along with computer processing to generate detailed cross-sectional images in both horizontal and vertical planes. Though they are usually not used to diagnose, it is used to confirm hip position after treatment. It shows detailed images of the hip and assesses the three-dimensional shape of the bones and the joint.
• Magnetic resonance imaging (MRI) – This technique utilizes strong magnets, radio signals, and computer processing to generate detailed images of the hip. MRIs do not expose infants to radiation and hence, the best way to look at the soft tissues around and in the hip joint.

Treatment

The appropriate treatment for DDH will be decided by your doctor.

It mainly depends:

• The baby’s gestational age, general health, and medical history
• Severity of the condition
• The baby’s ability to tolerate certain medications, procedures, or therapies
• Your opinion or preference

The aim of DDH treatment is to reposition the femoral head into the hip socket and deepen the socket to allow normal hip movement.

Treatment options for infants may include:

Pavlik Harness

The Pavlik Harness is worn by babies up to six months old to help position the hip correctly while still allowing limited leg movement. Your baby’s doctor fits the harness, which is typically worn full-time for several weeks, followed by part-time use for a few more weeks.

Throughout treatment, ultrasounds (or X-rays) are used to monitor the hip’s position and the socket’s development.

In most infants, the Pavlik harness successfully treats hip dysplasia, though some hips may remain partially or fully dislocated.

Body Casting (Spica Casting)

If the harness or brace does not work, the hip may need to be manually repositioned under anesthesia, a procedure called a closed reduction. If the procedure is successful, a custom-molded body cast, known as a spica cast, is applied to keep the hip in position. The hip spica cast typically extends from the chest to the ankle on the affected side and often covers part of the opposite leg as well.

The spica cast is generally worn for about three to six months. To accommodate the baby’s growth and hygiene, the cast is changed from time to time. After the cast is removed, a brace and/or physical therapy may be needed to help deepen the hip socket and strengthen the surrounding muscles.

Surgery

If a closed reduction fails, the next step is surgery, called an open reduction, to reposition the femoral head into the socket. In this, the surgeon directly visualises the ball and the socket by opening the hip joint. Following an open reduction, infants need a spica cast, typically worn for a shorter period than after a closed reduction.

Long-term Outlook for a Baby with DDH

Screening of newborns for DDH has allowed for earlier detection. When detected early, treatment usually involves using a harness or brace. The older a child is, the more likely it is that surgery becomes necessary.

Continued follow-up, even after successful treatment of DDH, is important in an infant because, as a child grows, the socket needs to be monitored to be sure that it is developing properly. Sometimes, further surgeries may be required to deepen the hip socket and reduce the risk of arthritis later in life.

Frequently Asked Questions