Developmental Dysplasia (DDH)

Involves dislocation or subluxation of the femoral head during the perinatal period which affects the subsequent development of the hip joint

Aetiology

  • Congenital
  • Poor positioning after birth
  • Higher incidence in females (8:1)
  • Breech presentations
  • Family history
  • Oliohydramnios
  • First born
  • Moulded baby (feet/neck/head/spine) e.g. twins
  • >4kg
  • Multiple pregnancy
  • Left hip more commonly involved

Pathophysiology

  • If left untreated the acetabulum is very shallow and in more severe cases a false acetabulum occurs proximal to the original one with a shortnened lower limb
  • Severe arthritis due to reduced contact area can occur at a young age and gait / mobility may be severely affected

Clinical presentation

  • Neonatal baby checks
  • Selective US screening in Scotland
    • Breech
    • 1st degree family member
    • Moulded
  • 6-8 week GP check
  • Late presentation - any time after 3 months, usually when child starts to walk (12-18 months)

Signs

  • Asymmetry
  • Loss of knee height
  • Crease asymmetry
  • Less abduction in flexion
  • Barlow's test - flex and adduct the hip, sign is positive if hip dislocates posteriorly
  • Ortolani's test - flexion and abduction reduces femoral head into acetabulum

Investigations

  • USS - preferred
    • Less helpful after 3 months of age as the ossification nucleus begins to develop
  • X-ray - cannot be used for the early diagnosis of DDH as the femoral head epiphysis is unossified until around 4‐6 months but xrays are the investigation of choice after this age

Management

Early DDH

  • Pavlik harness 23-24 hrs a day for up to 12 weeks until USS is normal
    • Hip abducted and flexed
    • May need night splints for a few weeks afterwards
  • 95% normal hip

Late DDH

  • Surgery - closed reduction (CR) spica, open reduction (OR) spica
  • For children with persistent dislocation over 18 months old OR is much more likely to be required and the acetabulum is likely to be very shallow by this stage
    • Typically the child will need an open reduction to clear soft tissues and may also need an osteotomy to shorten and rotate the femur and/or pelvic osteotomy to deepen and re‐orientate the acetabulum
  • Persistent or undiagnosed DDH at this stage tends to have a poorer prognosis - unable to construct a normal hip, 30% will require further surgery