Developmental Dysplasia of the Hip (DDH)

• Campbell's Operative Orthopaedics 15th Ed 2026, p. 1401
• Bailey and Love's Short Practice of Surgery 28th Ed, p. 637

Incidence

• True dislocation: ~1-2 per 1000 live births
• Neonatal instability (broader): ~20 per 1000 live births
• Ultrasound screening picks up far more cases, but many resolve spontaneously
• Left hip is more commonly affected than the right; bilateral > unilateral right involvement

Aetiology and Risk Factors

Pathology and Secondary Changes

• The capsule becomes permanently elongated
• The psoas tendon may obstruct reduction anteriorly
• The limbus acetabuli hypertrophies at the periphery
• The ligamentum teres hypertrophies and elongates
• The femoral head becomes reduced in size with posteromedial flattening
• Coxa valga and excessive anteversion develop
• The true acetabulum becomes shallow

Clinical Presentation (Age-Dependent)

Neonates (< 6 months)

• Ortolani test: With the hip flexed and abducted, a palpable clunk is felt as the posteriorly dislocated femoral head relocates into the acetabulum - a positive sign indicates a reducible dislocation.
• Barlow test: The flexed hip is adducted with posteriorly directed force; a palpable clunk of subluxation/dislocation is felt - a positive sign indicates an unstable hip.
• Limited hip abduction (most reliable sign after early infancy)
• Asymmetric skin folds (unreliable alone)

FIGURE: Clinical signs of DDH in a 13-month-old. A - decreased abduction of the right hip. B - positive Galeazzi sign (apparent femoral shortening on the dislocated side)

Infants (6-18 months)

• Shortened extremity, limited passive abduction
• Galeazzi sign: Apparent femoral shortening when hips and knees flexed
• Delayed ossification on X-ray; lateral and proximal displacement of femoral head

Walking-age children

• Trendelenburg gait - waddling, lurching toward the affected side
• Difficulty abducting the hip during diaper changes
• Bilateral dislocation may appear symmetrically abnormal and be missed

Adolescents and adults

• Exercise-induced hip pain
• Pain from degenerative arthritis (late complication)

Investigations

Ultrasound (first-line in infants < 6 months)

• High-frequency linear probe; coronal view with hip flexed and abducted
• Graf classification based on alpha (α) and beta (β) angles:
  • α angle (acetabular roof angle): Normal ≥ 60°
  • β angle (inclination line): Normal < 55°
  • Graf I = normal; II = immature/mild dysplasia; III/IV = subluxed/dislocated
• Dynamic stress views assess stability
• Preferred over X-ray in early infancy (femoral head is cartilaginous)

Radiograph (useful from ~4-6 months when ossification begins)

• Hilgenreiner line (horizontal through triradiate cartilage)
• Perkins line (vertical through lateral acetabulum)
• Femoral head should lie in the lower-inner quadrant of these intersecting lines
• Shenton's line continuity
• Acetabular index: Normal < 30° at birth, < 25° by 1 year
• Center-edge angle (reliable only after age 5)

CT/MRI

• Used for pre-operative planning or to assess reduction quality after surgery
• MRI preferred to avoid radiation in young children

Treatment (Age-Based)

Newborn - 6 months: Pavlik Harness (first-line)

Properly applied Pavlik harness. Hips held in flexion-abduction.

• Worn full-time (23 hours/day) initially, monitored with ultrasound every 2-4 weeks
• Success rate ~85-95% for reducible hips
• Contraindications: teratologic dislocations, fixed contractures, irreducible hips
• Complications: femoral nerve palsy (excessive flexion), osteonecrosis (excessive forced abduction)
• The Tübingen brace is an alternative with similar efficacy

Infant (6-18 months): Closed or Open Reduction

• Pavlik harness success drops sharply after crawling age
• Preoperative traction (2-4 weeks) to bring the femoral head closer to the acetabulum
• Adductor tenotomy to release contracture
• Closed reduction under general anesthesia with arthrogram confirmation, followed by hip spica cast
• Open reduction if closed reduction fails - medial or anterior approach
• Femoral shortening osteotomy may be needed for high dislocations to reduce neurovascular tension

Toddler (18-36 months) and Child (3-8 years)

• Open reduction is almost always required
• Combined with femoral osteotomy (to correct coxa valga/anteversion) and pelvic osteotomy (to redirect or augment the acetabulum)
• Common pelvic procedures: Salter osteotomy, Pemberton acetabuloplasty, Dega osteotomy

Older child/Adolescent/Adult (> 8 years)

• Surgical options more complex; outcomes less predictable
• Periacetabular osteotomy (PAO/Bernese) for symptomatic dysplasia without arthritis
• Total hip arthroplasty for end-stage osteoarthritis secondary to DDH

Complications

Screening Guidelines

• AAP (USA): Routine clinical screening of all newborns; ultrasound for positive exam or risk factors (breech, family history)
• UK (NIPE): Hip examination at birth and 6-8 weeks; ultrasound for at-risk infants
• Universal ultrasound screening is practiced in some countries (e.g., Germany, Austria) but evidence for universal vs. selective screening remains mixed - some studies show earlier treatment and fewer surgeries with universal screening, while others show increased unnecessary referrals

Recent Evidence

• Starting from newborn clinical examination with Ortolani and Barlow tests
• Three branches: normal exam without risk factors, normal exam with risk factors, and positive exam
• Ultrasound (Graf classification) drives the next decision point

• Graf I → routine follow-up, no treatment
• Graf IIa (< 3 months) → watchful waiting with repeat USS
• Graf IIb/IIc/D → Pavlik harness
• Graf III/IV → immediate Pavlik harness with close monitoring
• Pavlik harness response at 3-4 weeks determines continuation vs. escalation to reduction

• 0-6 months: Pavlik harness
• 6-18 months: closed reduction + hip spica cast
• 18 months - 3 years: open reduction ± femoral osteotomy
• 3-8 years: triple procedure (open reduction + femoral + pelvic osteotomy)
• > 8 years/adult: PAO or total hip arthroplasty

• Red alert box for AVN, redislocation, and residual dysplasia - the three most clinically significant risks to track throughout treatment.