The Waldenström classification of Perthes disease refers to x-ray abnormalities and represents four temporal phases of the disease. These stages have been further subdivided in the modified Elizabethtown classification 2.
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stage I: early
- asymmetric femoral epiphyseal size (smaller on the affected side)
- apparent increased density of the femoral head epiphysis
- widening of the medial joint space
- blurring of the physeal plate
- radiolucency of the proximal metaphysis
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stage II: fragmentation
- subchondral lucency (crescent sign)
- femoral epiphysis fragments
- femoral head outline is difficult to make out
- mottled density
- thickened trabeculae
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stage III: reparative
- re-ossification begins
- shape of the femoral head becomes better defined
- bone density begins to return
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stage IV: healed
- depending on the severity, the femoral head may be nearly normal or may demonstrate:
- flattening of the articular surface, especially superiorly
- widening of the head and neck of the femur
- depending on the severity, the femoral head may be nearly normal or may demonstrate:
History and etymology
The staging system originally described by J H Waldenström in 1922 had some differences in numbering (IA: initial stage, IB: fragmentation stage, II: healing period, III: growing period, IV: definite stage) 4. What is today widely known as Waldenström classification is probably better reflecting the classification used by S T Canale in 1972 5 and is therefore called Elizabethtown classification by some 2.