What are the risk factors for Legg-Calve-Perthes disease?

Risk Factors for Legg-Calvé-Perthes Disease

The most significant risk factors for Legg-Calvé-Perthes disease include age between 4-8 years, male gender, low body weight, and certain racial/ethnic backgrounds, with additional risk from family history and environmental factors that may contribute to vascular compromise of the femoral head.

Primary Risk Factors

Demographic Risk Factors

• Age: Typically occurs between 4-8 years of age, but can occur between ages 2-15 1
• Gender: Males are 4-5 times more commonly affected than females 2
• Prognosis by age and gender:
  • Children under 6 years generally have good prognosis
  • Children 6-8 years have variable prognosis
  • Children over 8 years have poorer prognosis 1
  • Female patients over 8 years at disease onset have significantly worse outcomes than males of the same age 3

Physical Characteristics

• Body weight: Lower BMI is associated with increased risk 4
• Race/Ethnicity: Higher incidence in Caucasians and Asians, lower in African Americans 2

Secondary Risk Factors

Anatomical and Physiological Factors

• Vascular abnormalities: Interruption of blood supply to the femoral head is the primary pathological mechanism 1, 5
• Skeletal maturation: Delayed bone age is common in affected children 4
• Hip joint abnormalities: Pre-existing abnormalities in hip development may contribute to risk

Environmental and Other Factors

• Family history: 1.4x increased risk with positive family history 2
• Birth order: Higher risk in firstborn children 2
• Geographic variations: Higher incidence in certain regions (Northern Europe, Japan, Central Europe) 4
• Socioeconomic factors: Higher prevalence in lower socioeconomic groups 6

Clinical Implications

Prognostic Indicators

• Lateral pillar classification: Strong prognostic indicator for disease outcome 3
  • Group B and B/C border hips in children >8 years benefit most from surgical intervention
  • Group C hips have poorest outcomes regardless of treatment
• Femoral head involvement: Extent of epiphyseal involvement directly correlates with prognosis 5
• Clinical signs: Poor prognosis associated with:
  • Limited hip abduction
  • Overweight status
  • Female sex
  • Age >6 years 4

Monitoring Recommendations

• Regular physical examinations: Focus on hip abduction, asymmetry of thigh or gluteal folds, and leg length discrepancy 2
• Imaging surveillance:
  • Radiographic follow-up to assess femoral head involvement
  • MRI to evaluate extent of avascular necrosis and revascularization 2

Management Considerations

The presence of multiple risk factors should guide treatment decisions, with age at onset and lateral pillar classification being the strongest prognostic factors 3. Children over 8 years of age with lateral pillar B or B/C classification benefit most from surgical intervention, while those under 8 years with group B classification have favorable outcomes regardless of treatment approach 3.

Regular monitoring through skeletal maturity is essential, as complications can develop during growth spurts, particularly in high-risk patients 2.