Developmental Dysplasia of the Hip

• DDH covers a spectrum of varying degrees of superolateral displacement of the femur and deformation of the acetabulum, developing mostly in utero or, rarely, in infancy.
• It usually is discovered on routine screening in early childhood.
• It occasionally is discovered in teens with a limp or pain, in which case it probably represents a mildly subluxed hip that could not be detected on physical examination.
• Classification by spectrum of severity:
  • A subluxable hip is reduced but can be subluxated with pressure and goes back to the reduced position.
  • A dislocatable hip can be fully dislocated and reduced.
• A dislocated hip rests in a dislocated position and reduces only with manual effort.
• Synonyms: DDH; Congenital dislocation of the hip (old term); Hip dysplasia; Unstable hip

• No effective preventive means exist.
• Early detection is most important.
• Patients with hip dysplasia should have their children examined carefully at birth.

• Breech position
• 1st-born status
• Female gender
• Oligohydramnios
• Family history
• Ehlers-Danlos or Marfan syndromes

• Dysplasia occurs because of unfavorable forces on the hip in utero.
• Adduction of the limb, such as with oligohydramnios, directs the femoral head to the edge of the acetabulum.
• Breech position increases hamstring tension and thus the force across the hip.
• Ligamentous laxity, greater in females and in some families, also increases the risk.
• The earlier in utero these factors develop, the more severe the dysplasia.
• Postpartum factors, such as a contralateral abduction contracture or swaddling of the limbs, prevent some hips from stabilizing on their own.

• Muscular torticollis
• Foot deformities
• Genetic syndromes (especially connective-tissue disorders and skeletal dysplasia)

• No symptoms appear during the 1st few years of life.
• Only careful physical examination for a gentle clunk of the hip out of (Barlow sign) or into (Ortolani sign) the acetabulum shows the problem.
• The affected hip may rest in slight adduction and may have a deeper proximal thigh crease, but these signs are not constant.
• The abduction of the affected limb usually is <50° because of the changed center of rotation.
  • The parent may note this adduction limitation while changing the infant’s diapers.
  • A click may be felt in the hip, but it is a nonspecific sign because a click often is felt in normal hips and comes from the meniscus of the knee, fascia lata, or a synovial fold.
  • The clunk of instability usually is lost after ~6 months, when the dislocation becomes more fixed.
• The child with a dysplastic hip may begin to walk on time or just a few months late.
  • After walking age, the thigh crease may become more pronounced, and the circumference may be decreased.
  • A Trendelenburg limp may be noted (the pelvis drops when the patient stands on the dysplastic side).
  • If both sides are affected, increased lumbar lordosis may be present.
  • Pain develops only after cartilage degeneration starts at 18 years of age at the earliest, and often much later.
  • Associated conditions should raise the suspicion of hip dysplasia.

• Benign soft-tissue click from hip or knee fascia
• Neuromuscular hip dysplasia from muscle imbalance in cerebral palsy or spina bifida
• Congenital short femur and coxa vara, but with located hip

• The hip should be reduced within the 1st 6 weeks if the dislocation is recognized.
• The earlier the diagnosis is made, the easier and safer the treatment will be.
• Even up until age 6-8 years, reduction is worthwhile but requires surgery.
• Treatment varies according to age.
  • Newborn:
    • Click and subluxation are followed with serial examinations.
    • Many patients improve within 1 week.
  • Newborn-6 months:
    • Full dislocation or persistent instability is treated with an abduction brace, such as the Pavlik harness, which flexes the hip beyond 90° .
    • Bracing should be done by an orthopaedist familiar with pediatrics.
    • The hip should reduce within 3 weeks, which should be confirmed with ultrasound or radiography.
    • A full-time brace is used until the hip is clinically stable; then, a part-time brace is used until the hip is radiographically normal.
    • After 6 months: Closed versus open reduction.

• A medial or lateral approach to the hip joint is used to release the structures inside the joint that are blocking reduction.
• Osteotomy of the pelvis or femur is done to realign the joint surface.
• The approach depends on patient age.
  • 6-24 months:
    • Many surgeons proceed with a period of skin traction first to stretch the soft tissues.
    • Closed or open reduction with the patient under anesthesia
    • After reduction, spica cast for 3-6 months
  • >24 months:
    • Open reduction, usually including a femoral osteotomy or iliac osteotomy
    • The results of surgical reduction decline with the increasing age of the child.

• Untreated complete dislocation results in a permanent waddling (Trendelenburg) gait and pain by age 30-50 years at the latest.
• Patients with subluxed, but not dislocated, hips may have pain earlier.
• Hips that are successfully treated early may have normal function.

• Redislocation (5%)
• Residual dysplasia (25%)
• AVN (10%) :
  • If the blood supply to the upper femur is disturbed by the process of reduction
  • It may be impossible to reverse this process fully.

• After treatment of a dysplastic hip, follow-up care is needed until the patient reaches maturity.
• Even after successful hip reduction, a 10-25% chance exists of incomplete remodeling of the femur and acetabulum that may require osteotomy.

• The monitoring of skin around casts and braces is important.
• Infants in Pavlik harness should wear the device continuously until the hip is stable.
• Older children are treated in a spica (body) cast, so walking is not possible.
• Special car seats and wheelchairs are available.

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