Perthes disease (summary)
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This is a basic article for medical students and other non-radiologists
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.
- 5 times more boys than girls
- peak presentation at 5-6 years (CI 2-14 years)
- atraumatic hip pain or limp
- may be coincidental history of trauma (precipitates presentation)
- 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
- 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
- symptom control in the early phase
- degeneration as the disease progresses may require operative
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.
On MRI, we are looking for bone edema and evidence of an effusion. Bone edema will be bright of fluid-weighted sequences, e.g. T2/STIR.