Developmental Dysplasia of the Hip (DDH) – Causes, Risk Factors, Diagnosis & Treatment

Developmental Dysplasia of the Hip (DDH) is an orthopedic condition seen in infants and young children, characterized by abnormal development of the hip joint. The hip is a ball-and-socket joint where the femoral head (ball) fits into the acetabulum (socket). In DDH, this relationship is disturbed due to instability, leading to subluxation, dislocation, or improper joint formation (dysplasia).

Early detection is critical because newborn bones are not fully ossified and can be manipulated into proper alignment. If left untreated, DDH can result in long-term complications such as gait abnormalities, limb length discrepancy, early osteoarthritis, and chronic pain.

Pathophysiology

In infants, the hip joint is primarily made of cartilage, which allows greater mobility but also increased susceptibility to instability. In DDH:

• The acetabulum may be shallow or improperly formed.
• The femoral head may not be well-seated within the socket.
• Ligament laxity (common in newborns) contributes to instability.

Three terms are used to classify the severity:

• Dislocation: No contact between femoral head and acetabulum.
• Subluxation: Partial displacement; femoral head partially in contact with acetabulum.
• Dysplasia: Malformation of the acetabulum, preventing proper joint congruency.

Risk Factors for DDH

Several risk factors increase the likelihood of hip dysplasia:

• Female infants: Maternal hormones (relaxin) increase ligament laxity.
• Breech positioning: Babies born buttocks-first have increased risk of hip instability.
• Oligohydramnios: Low amniotic fluid restricts fetal movement, increasing joint stress.
• First-born infants: Tighter uterine and abdominal space may restrict movement.
• Family history: Genetic predisposition plays a significant role.

Clinical Features and Diagnosis

Clinical Signs in Infants:

• Asymmetry of thigh or gluteal folds.
• Limited abduction of the affected hip.
• Apparent leg length discrepancy (positive Galeazzi sign).
• Hip "clunk" felt during manipulation.

Physical Tests:

• Barlow Test: The examiner adducts and gently applies pressure on the thigh to attempt dislocation.
• Ortolani Test: The examiner abducts the hip while lifting the femoral head into the acetabulum, producing a palpable "clunk."

Imaging:

• Ultrasound: Preferred for infants younger than 6 months, as hip bones are not fully ossified.
• X-ray: Used after 6 months when ossification centers are visible.

Complications of Untreated DDH

If not detected and treated early, DDH can lead to:

• Avascular necrosis of the femoral head due to impaired blood supply.
• Reduced range of motion (ROM) of the hip.
• Leg length discrepancy.
• Early-onset osteoarthritis.
• Femoral nerve palsy in severe cases.

Treatment of Developmental Dysplasia of the Hip

Early intervention is essential, as infant bones are more malleable and can be guided into proper growth.

1. Infants Younger Than 6 Months

Pavlik Harness is the first-line treatment.

• Holds the hips in flexion and abduction.
• Prevents extension, ensuring femoral head remains in the acetabulum.
• Must be worn continuously, with regular monitoring by healthcare providers.
• Parents must check skin for irritation, change diapers while harnessed, and avoid removing or adjusting straps.

2. Infants 4 Months – 2 Years

Closed Reduction with Spica Cast

• Performed under anesthesia.
• Surgeon repositions the femoral head into the acetabulum.
• A spica cast is applied to maintain position.
• After cast removal, bracing may continue until the acetabulum develops normally.

3. Children Older Than 2 Years or Failed Non-Surgical Therapy

Open Surgical Reduction

• Required when the hip cannot be stabilized with harness or closed reduction.
• Surgical correction followed by immobilization in a cast.

Prognosis

When diagnosed early and treated appropriately, DDH has an excellent prognosis. The Pavlik harness achieves high success rates in infants diagnosed within the first 6 months. However, late diagnosis often requires surgery and carries a higher risk of long-term complications such as arthritis or gait abnormalities.

Preventive Strategies

While DDH cannot always be prevented, certain practices reduce risk:

• Avoid tight swaddling of legs in extension; hips should remain flexed and abducted.
• Encourage safe hip positioning in carriers and car seats.
• Screen newborns routinely, especially those with risk factors.

Table: Summary of DDH

Feature	Details
Definition	Abnormal development of the hip joint
Types	Dislocation, Subluxation, Dysplasia
Risk Factors	Female sex, breech birth, oligohydramnios, family history
Diagnosis	Barlow & Ortolani tests, ultrasound (<6 months), X-ray (>6 months)
Complications	Avascular necrosis, osteoarthritis, leg length discrepancy
Treatment (<6 mo)	Pavlik harness
Treatment (4 mo–2 y)	Closed reduction + spica cast
Treatment (>2 y)	Open reduction surgery

Conclusion

Developmental Dysplasia of the Hip (DDH) is a significant orthopedic condition that requires early screening, accurate diagnosis, and timely intervention. With newborn hip exams and appropriate treatment such as the Pavlik harness or surgical reduction, most children can achieve normal hip development and avoid long-term complications.

FAQs on DDH

Q1. What is the difference between hip dysplasia and dislocation?

Dysplasia refers to abnormal joint formation, subluxation is partial displacement, and dislocation is complete loss of contact between femoral head and acetabulum.

Q2. Can DDH be detected before birth?

Yes. Ultrasound in utero can sometimes identify abnormal hip positioning, but most diagnoses occur postnatally.

Q3. How long should a Pavlik harness be worn?

Typically for 6–12 weeks, depending on the severity and response to treatment, under close monitoring.

Q4. Does DDH affect both hips?

It can be unilateral or bilateral, though unilateral cases are more common.

Q5. What happens if DDH is left untreated?

Untreated DDH can cause lifelong complications such as gait abnormalities, chronic hip pain, and early-onset osteoarthritis.