DDH

Developmental Dysplasia of the Hip (DDH)

Epidemiology

  • Predominantly affects girls: 80%
  • Side Predominance: 60% left, 20% right, 20% bilateral
  • Incidence: 1 in 1,000 live births

Aetiology

DDH develops postnatally and is not a congenital condition. Known risk factors include genetic predisposition and intrauterine conditions.

Genetic and Intrauterine Factors

  • Genetic: Risk increases with the number of 1st-degree relatives with DDH.
  • Gender Factor: Females more susceptible due to ligamentous laxity and oestrogen influence.

Intrauterine Factors Contributing to Crowding

  • Firstborn children: Tighter uterus
  • Breech Presentation
  • Oligohydramnios
  • Multiples (e.g., twins)

Associated Overcrowding Disorders

  • Torticollis
  • Congenital knee dislocation
  • Metatarsus adductus
  • Congenital Talipes Equinovarus (CTEV)

Neuromuscular Factors

  • Late dislocations requiring aggressive treatment
  • Common in conditions such as spina bifida and cerebral palsy (CP)

Teratologic DDH

  • Irreducible dislocation requiring surgical intervention, commonly associated with conditions like arthrogryposis

Pathophysiology

  • Acetabular Development: The femoral head’s placement influences acetabular shape, determined by 8 years of age.
  • Common Findings: Shallow acetabulum and femoral anteversion.

Clinical Diagnosis

History

  • Family history, birth presentation, and associated conditions

Physical Examination

  • Leg Lengths: Galeazzi test
  • Range of Abduction
  • Skin Creases
  • Barlow and Ortolani Tests: Used for dislocation and relocation assessment
  • In Older Children:
    • Spinal deformity
    • Compensatory lumbar lordosis
    • Apparent leg length discrepancy
    • Hip flexion contracture
    • Pelvic obliquity and impingement pain

Imaging Techniques

Ultrasound (Under 4 months)

  • Graf Angles:
    • Alpha Angle: >60 degrees (decreases as acetabulum shallows)
    • Beta Angle: <55 degrees (increases as acetabulum shallows)

X-Ray (Post-ossification of femoral head)

  • Key Measurements:
    • Perkins Line: Femoral head should reside in the infero-medial quadrant
    • Shenton’s Line
    • Acetabular Index: 30 degrees at birth, 24 degrees by 24 months
    • Center Edge Angle (CE): >20 degrees (for children over 5 years)

Arthrography

  • Used intraoperatively for stability and reducibility assessment

Management

Natural History of Untreated DDH

  • Unilateral DDH: Leg length discrepancy, scoliosis, hip contracture, valgus knee, and osteoarthritis (OA)
  • Bilateral DDH: Hyperlordosis, back pain, impaired gait

Goals of Treatment

  • Concentric and stable reduction
  • Normal growth and hip development
  • Avoidance of complications

Primary Factor for Treatment: Age at diagnosis

Age-Based Management

Age 0 – 4 Months

Pavlik Harness - First-line for Ortolani-positive (reducible) hip - Position: 90 degrees flexion, 45 degrees abduction, neutral rotation - Monitoring: 23 hours/day for 6-8 weeks, then night use for 6 weeks; repeat ultrasound - Failures: Closed reduction and Spica casting if unsuccessful by 4 weeks

Complications - Femoral Nerve Palsy: Excessive flexion - Inferior Dislocation: Excessive flexion - Skin Problems: Harness too tight - Pavlik Disease: Erosion of the pelvis - Avascular Necrosis (AVN): Excessive abduction compressing the posterior superior branch of MCF artery

Arthrography, Closed Reduction, and Spica Casting

  • Performed under general anesthesia
  • Fluoroscopy and injection of dilute Omnipaque for visualization
  • Closed Reduction: Evaluate Safe Zone (stable abduction range); if narrow, consider adductor tenotomy
  • Spica Casting: 3 months; checked at 6 weeks, possible removable abduction brace for 6-12 weeks

Open Reduction & Hip Spica (Age usually >4 months)

  • Indicated for irreducible hip, non-concentric reduction, very narrow Safe Zone, or failed closed treatment
  • Anatomical obstructions to be addressed: Iliopsoas and adductor tendons, ligamentum teres, and acetabular pulvinar

Age 4 – 18 Months

  • Pavlik Harness not suitable
  • Options:
    • Arthrography, closed reduction, and Spica (with tenotomy as needed)
    • Open reduction with Hip Spica
  • Follow-Up: X-ray or CT to confirm reduction

Age 18 Months to 8 Years

Primary Treatment: Open Reduction and Hip Spica - Open Reduction with femoral or pelvic osteotomy if required for stable reduction

Osteotomy Choices - Femoral: Easier with less morbidity, encourages acetabulum remodeling - Pelvic: Ideal for severe acetabular dysplasia

Over 8 Years

  • Limited remodeling potential of acetabulum
  • Unilateral DDH: Open reduction not recommended
  • Bilateral DDH: Upper limit is 6 years; risks outweigh benefits

Pelvic Osteotomies

Types of Osteotomies

  1. Salter (Redirectional): Preferred for younger children; hinges on pubic symphysis.
  2. Double & Triple Innominate: Higher correction; useful in older children.
  3. Ganz Periacetabular: Excellent correction, triradiate closure necessary.
  4. Pemberton (Volume Reducing): Pivots at triradiate cartilage.
  5. Dega (Volume Reducing): Suitable for paralytic conditions.
  6. Chiari (Salvage – Volume Increasing): Concentric reduction not possible.
  7. Shelf Procedures (Salvage – Volume Increasing): Augments acetabulum for lateral head coverage.
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