Perthes disease (summary)

Perthes disease is the name given to idiopathic AVN (avascular necrosis) of the femoral epiphysis in children. It most often occurs in children around the age of 5-6 years and is one of the common considerations when children present with an atraumatic limp or hip pain.

Reference article

This is a summary article. For more information, you can read a more in-depth reference article: Perthes disease.

Summary

• epidemiology
  • 5-15/100,000
  • 5 times more boys than girls
  • peak presentation at 5-6 years (CI 2-14 years)
• presentation
  • atraumatic hip pain or limp
  • may be coincidental history of trauma (precipitates presentation)
• pathology
  • lack of blood supply to the femoral head
  • fragmentation and bone loss
  • 15% of cases are bilateral
  • cause of AVN in Perthes disease in unclear
• radiology
  • pelvic radiograph for assessment and diagnosis
  • MRI for persistent pain in children with normal radiographs
  • US may detect an effusion, but is not sensitive for AVN
• treatment
  • symptom control in the early phase
  • degeneration as the disease progresses may require operative

Radiographic features

X-rayPlain radiograph

The radiographic changes to the femoral epiphyses depend on the severity of AVN and the amount of time that there has been alteration of blood supply:

• early: there may be no appreciable change
• established: reduction in epiphysis size, lucency
• late: fragmentation, destruction

As changes progress, the width of the femoral neck increases (coxa magna) in order to increase weight-bearing support.

MRI

On MRI, we are looking for bone oedema and evidence of an effusion. Bone oedema will be bright of fluid-weighted sequences, e.g. T2/STIR.​