Legg-Calve-Perthes disease; pseudocoxalgia; avascular necrosis of the hip

Epidemiology

• children 3-12 years of age
  • peaking between 5-7 years of age
  • male/female ratio = 4

Pathology

• osteonecrosis of the femoral head occurring in a child
• interruption of the blood supply to the capital femoral epiphysis is the cause of the osteonecrosis
• stage 1: femoral head becomes more dense with possible fracture of supporting bone
• stage 2: fragmentation & reabsorption of bone
• stage 3: reossification when new bone has regrown

Genetics

• associated with defects in COL2A1

Clinical manifestations

• children usually present with a limp or pain in the hip, thigh or knee
• examination of the knee is normal
• limited range of motion with hip pain on internal rotation & abduction of the ipsilateral hip
• may vary, depending on the phase of disease progression through ischemia, revascularization, fracture & collapse, & repair & remodeling of the bone

Radiology

• anteroposterior & frog-leg lateral radiographs of the hip
  • may show evidence of bone necrosis, fragmentation, reossification or remodeling & healing
  • earliest signs include decreased size or increased density of the proximal femoral epiphyses on an AP view & crescent sign (subchondral fracture that correlates with extent of necrosis) on lateral view

Management

• rest, avoid aggravating activities
• range of motion exercises
• occasionally orthoses or surgery may be required
• prognosis
  • femoral head involement of > 50% predicts poor outcome
  • age > 6 years confers worse prognosis

More general terms

• osteochondrosis
• avascular osteonecrosis; aseptic necrosis
• developmental disorder

Database

• OMIM: https://mirror.omim.org/entry/150600