What Is Hip Dysplasia?

Hip dysplasia is a condition that occurs when the hip socket (acetabulum) is too shallow to fully support the ball of the hip joint, called the femoral head. This typically affects a developing fetus, a condition called congenital hip dysplasia or developmental dysplasia of the hip (DDH). However, symptoms can appear during adolescence or even in adulthood.

This article discusses hip dysplasia—what it is, what causes it, how it is diagnosed, treatment options, and how to live well with it.

Types of Hip Dysplasia

Hip dysplasia can be categorized by how severely damaged the hip joint is. Categories from least to most severe include:

• Subluxatable: The ball of the hip joint is loose in the socket but does not pop out of place.
• Dislocatable: The ball of the hip joint is in the socket but can be pushed out of it during a physical exam.
• Dislocated: The ball of the hip joint is completely out of the socket.

Hip Dysplasia Symptoms

Symptoms of hip dysplasia in babies can include:

• Legs that look like they are different lengths
• One leg that doesn't move as easily as the other
• Uneven folds of skin on the thighs

Sometimes, symptoms of hip dysplasia are not obvious until a child starts walking. Symptoms can then include:

• Limping
• Walking on tip toes
• A waddling gait (the manner of walking)

Early on, hip dysplasia is not a painful condition. However, if it is not corrected, it can cause damage to structures in the hip joint, such as the cartilage that provides padding between the bones or cartilage around the edge of the socket (the labrum).

The primary symptom of hip dysplasia during the adolescent years or early adulthood is pain. This pain usually occurs in the groin area or outer hip and worsens with activity. The affected hip might also feel like it locks up, catches, or pops.

Causes of Hip Dysplasia

The exact cause of hip dysplasia isn't known. But, contributing factors increase the risk of developing this condition. These include:

• Additional family members with hip dysplasia
• Assigned female at birth
• Positioning of the fetus in the womb
• Breech birth (a baby delivered buttocks or feet first)
• Frequently swaddling babies with their legs straight and close together
• First born child
• Lower levels of amniotic fluid

Diagnosis

Newborns are typically screened for hip dysplasia soon after delivery using the Barlow and Ortolani tests, which assess hip function.

During a physical exam, the healthcare provider will move the baby's hips while listening and feeling for a "click" or "clunk," which can indicate that the hip joints might not have developed properly.

An ultrasound is sometimes performed to confirm the diagnosis if hip dysplasia is suspected.

Diagnosing hip dysplasia in adolescents also involves a physical exam. A healthcare provider will move the hip joint in different directions to see which movements cause pain. Hip dysplasia can be confirmed with various imaging tests. These tests can also assess for damage in other structures of the hip joint.

Imaging tests can include:

• X-rays
• Computed tomography (CT scan or CAT scan)
• Magnetic resonance imaging (MRI)

Treatment

Treatment for hip dysplasia depends on the severity of the condition and when it is first diagnosed.

Newborns through 6-month-old infants are typically treated with a soft brace called a Pavlik harness. The brace is usually worn all the time for the first six weeks, then worn only at night for an additional six weeks.

The Pavlik harness holds the infant's legs in a bent position, with the hips outwardly rotated. This position helps the hip socket to deepen as the infant grows.

If the harness is not adequate enough to keep the ball in the socket, the baby is given anesthesia, and a healthcare provider moves the bones into the correct position (closed reduction); this does not require surgery. A cast is then applied for two to three months to hold the leg(s) in the proper position as the infant grows.

Infants older than 6 months and children who develop symptoms during adolescence might need surgery to correct the position of the ball in the socket. A cast is applied afterward for approximately two to three months as the joint heals.

Additional surgeries—such as an osteotomy (a procedure involving bone-cutting)—are sometimes required to treat joint damage resulting from hip dysplasia. Nonsteroidal anti-inflammatory drugs (NSAIDs) such as Advil (ibuprofen) or Aleve (naproxen), and physical therapy can also help treat pain and decreased range of motion that develops with this condition.

Summary

Hip dysplasia is a condition that occurs when the socket of the hip joint (acetabulum) does not develop properly, allowing the ball of the hip joint (femoral head) to move out of place. The exact cause of hip dysplasia isn't known, but the condition tends to run in families and affects females more often than males. It is also more common with breech births.

Hip dysplasia in infants is not painful, but pain is the primary symptom adolescents experience when the condition has not been diagnosed at a younger age. The condition is diagnosed with the Barlow and Ortolani tests and can be confirmed with imaging. Treatment can include wearing a brace, closed reduction with casting, or, less commonly, surgery.