Developmental Dysplasia of the Hip (DDH)
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
