Introduction

Perthes disease (also Legg-Calvé-Perthes disease) is a childhood hip disorder that results in avascular necrosis of the femoral head.

The cause is unknown.

It can be differentiated from adult onset osteonecrosis because in Perthes there is healing and bone remodelling, whilst in osteonecrosis there is not.

Epidemiology and Aetiology

• Can occur between ages of 2 and 12, but most commonly between 4 and 8
• 10 -20% of cases are bilateral – but often has at different stages of disease
• M:F – 5:1
• 1 in 10,000
• Higher incidence in urban areas
• Higher incidence amongst lower socioeconomic class
• Higher incidence at high latitude (low at equator)
• Associated with thrombophilia – in up to 50% of patients (and 75% of patients have some sort of clotting abnormality) – thought to be related to protein C and S deficiencies (controversial)
• Other risk factors include
  • Low birth weight
  • Second hand smoke
  • Caucasian, Asian, Inuit descent

Pathology

• Disruption of blood supply causing avascular necrosis of the femoral head
• Self-limiting process – an initial ischaemic event with later healing. The whole process can take 2-5 years
• Subsequent revascularization which causes reabsorption of the bone and collapse of the femoral head
• Then, there is remodelling of the femoral head
• Good prognostic factors
  • Younger age at presentation
  • Spherical femoral head (i.e. it has not yet collapsed)
  • Female
• Long term
  • 50% of patient develop OA
  • Most patient maintain good function until 5th or 6th decade of life

Presentation

• Pain and limp – often chronic and insidious course. Early detection can be difficult
• Restricted ROM on hip examination
• Antalgic gait
• Trendelenburg gait
• Limb length discrepancy (late finding)

Differentials

• Slipped Capital Femoral Epiphysis (SCFE)
  • Usually older children (mean age around 12)
  • Can be acute or chronic
  • Associated with obesity
• Septic Arthritis
  • Child often unwell
  • Signs of sepsis
  • Bloods suggestive of infection (raised WCC and CRP)
• Transient Synovitis
  • Usually younger children
  • Always acute
  • Resolves within a few days
  • Investigations normal

Investigations

• X-ray – AP and frog leg lateral
  • Joint space widening
  • Irregularity of femoral head
  • Crescent sign
• Bone scan
  • Can be diagnostic
  • Can show level of femoral head involvement
• MRI
  • Can show early features when other investigations are negative
  • More sensitive than x-ray
• Bloods – wil be normal

Management

• Usually non-operative
  • NSAIDs
  • Traction
  • Crutches
  • Physio
• Aim to restore ROM and limit disability
• Younger patients are least likely to benefit from surgery
• Surgical management
  • Indicated in children over 8 and severe disease

Complications

• Femoral head deformity
• Lateral hip subluxation
• Premature arrest of epiphyseal plate – causing leg length discrepancy
• Labral injury
• Osteochondritis Dessicans
• Degenerative Arthritis

References

Perthes’ Disease Factsheet – SCHN

Legg-Calve-Perthes Disease (Coxa plana) – Orthobullets

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