Developmental Dysplasia of the Hip (DDH)

Definition

DDH represents a spectrum of anatomical abnormalities affecting the developing hip joint, ranging from mild acetabular dysplasia to complete dislocation. It's a dynamic condition that can present at birth or develop during early childhood.

Key Concepts

• Spectrum of disease:
  • Acetabular dysplasia
  • Subluxation
  • Dislocation (reducible or irreducible)
  • Teratologic dislocation (occurs in utero)
• Critical periods:
  • Prenatal development
  • First 6-8 weeks of life
  • Walking age transition

Anatomical Considerations

• Normal hip development requires:
  • Concentric reduction of femoral head
  • Proper acetabular development
  • Balanced muscle forces
  • Unrestricted range of motion

Risk Factors & Epidemiology

Epidemiology

• Incidence:
  • 1-2 per 1000 live births in general population
  • Higher in certain ethnic groups (Native Americans, Lapps)
• Gender distribution: Female predominance (80%)

Risk Factors

• Primary Risk Factors:
  • Female gender
  • First-born status
  • Breech presentation (risk increased 17-fold)
  • Positive family history
  • Oligohydramnios
• Associated Conditions:
  • Torticollis
  • Metatarsus adductus
  • Congenital muscular torticollis
  • Foot deformities
• Genetic Factors:
  • Ligamentous laxity
  • Hormonal influences
  • Carter and Wilkinson criteria

Clinical Assessment

Physical Examination

• Newborn Examination:
  • Ortolani test (reduction maneuver)
  • Barlow test (provocation maneuver)
  • Limited abduction
  • Asymmetric skin folds
• Infant Examination (3-6 months):
  • Limited abduction
  • Apparent leg length discrepancy
  • Galeazzi sign
  • Asymmetric thigh folds
• Walking Age:
  • Trendelenburg gait
  • Waddling gait
  • Leg length discrepancy
  • Limited running ability

Clinical Signs Explanation

• Ortolani Test:
  • Reduction of dislocated hip
  • Palpable/audible clunk
  • Most reliable in newborns
• Barlow Test:
  • Provocation of unstable hip
  • Posterior stress application
  • Assessment of subluxation

Imaging Studies

Ultrasound Evaluation

• Primary screening tool < 4-6 months:
  • Graf classification system
  • Dynamic assessment
  • Measure alpha and beta angles
• Graf Classification:
  • Type I: Normal hip
  • Type II: Physiologically immature/mild dysplasia
  • Type III: Subluxated hip
  • Type IV: Dislocated hip

Radiographic Evaluation

• AP Pelvis (>4-6 months):
  • Hilgenreiner's line
  • Perkins line
  • Shenton's line
  • Acetabular index
• Key Measurements:
  • Acetabular index (normal <30 degrees)
  • Center-edge angle
  • Migration percentage

Treatment Approaches

Age-Based Treatment

• 0-6 months:
  • Pavlik harness (primary treatment)
  • Success rate 90% if initiated early
  • 23/7 wearing schedule
  • Weekly monitoring
• 6-18 months:
  • Closed reduction + spica casting
  • Arthrogram guidance
  • Post-reduction imaging
• >18 months:
  • Open reduction often necessary
  • Pelvic/femoral osteotomy consideration
  • Staged procedures may be needed

Pavlik Harness Management

• Application Technique:
  • Proper sizing
  • Shoulder strap adjustment
  • Anterior strap positioning
  • Leg strap placement
• Monitoring:
  • Weekly clinical checks
  • Ultrasound assessment
  • Parent education
  • Complications watch

Complications & Follow-up

Potential Complications

• Early Complications:
  • Pavlik harness failure
  • Femoral nerve palsy
  • Skin irritation
  • Parent compliance issues
• Late Complications:
  • Avascular necrosis
  • Residual dysplasia
  • Growth disturbance
  • Early osteoarthritis

Long-term Follow-up

• Monitoring Schedule:
  • Regular clinical assessment
  • Radiographic surveillance
  • Growth monitoring
  • Activity modification as needed
• Transition to Adult Care:
  • Education about long-term risks
  • Activity counseling
  • Family planning discussions
  • Regular screening intervals