FFinalistSouthampton · 2027
Child health
AKT · Child health/Growth, GI & MSK

Perthes disease

Idiopathic avascular necrosis of the femoral head

Overview

Idiopathic avascular necrosis of the femoral head in children (typically 4–8 years, boys), causing a gradual painless limp and hip/knee pain, with collapse then revascularisation of the femoral head.

Recognise

  • Insidious limp and hip/groin/KNEE pain in a 4–8-year-old (more common in boys)
  • Reduced internal rotation and abduction
  • Usually no systemic upset

Red flags

  • Bilateral disease → consider epiphyseal dysplasia/hypothyroidism; older child with acute slip = SUFE

Differentials & how to tell them apart

Transient synovitisacute, post-viral, self-limiting over days — Perthes is insidious and persistent
SUFEolder (10–15y), often overweight, externally rotated leg
Septic arthritisfebrile, unwell, refuses to weight-bear
Juvenile idiopathic arthritismultiple joints, morning stiffness

Investigations

X-ray (AP + frog-leg lateral): early — widened joint space, then sclerosis, fragmentation, flattening of the femoral head. MRI if X-ray normal but suspicion high.

Management

Observation and physiotherapy (containment surgery if severe/older)

  1. 1Younger children/mild: observation, analgesia, physiotherapy to preserve movement and containment.
  2. 2Older or severe femoral head involvement: containment with bracing or osteotomy.
Observation + physiotherapy — maintain range of movement; younger/milder
Containment (bracing/surgery) — older children / severe head involvement

Key points

Hip pathology often presents as KNEE pain in children — always examine the hip. Perthes is insidious; transient synovitis is acute and brief.

Monitor & prognosis

Serial X-rays; range of movement; femoral head shape.

Younger age and less head involvement do better; risk of later osteoarthritis.

Source: Paediatric orthopaedics