Perthes Disease

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Contents

Introduction
Epidemiology and Aetiology
Pathology
Presentation
Differentials
Investigations
Management
Complications
References
Related Articles

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

Perthes Disease x-ray showing bone remodelling of the femoral head. Image James Heilman, MD. From wikimedia commons. Used under Creative Commons Attribution-Share alike 4.0 international license.

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