Erlenmeyer flask deformity

Erlenmeyer flask deformity (EFD) (also known as metaphyseal flaring) refers to a radiographic appearance typically on a femoral radiograph demonstrating relative constriction of the diaphysis and flaring of the metaphysis.

It has been classically used with reference to the distal ends of the femora, however it is also seen in the proximal humeri, tibiae, and the distal radii and ulnae 4


The causes can also be remembered with the mnemonics CHONG or Lead GNOME.

History and etymology

The conically-shaped flask with a wide base and short narrow neck was created by the German chemist Emil Erlenmeyer (1825–1909) in 1860 3.

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Article information

rID: 1298
Section: Gamuts, Signs
Tag: refs
Synonyms or Alternate Spellings:
  • Metaphyseal flaring
  • Erlenmeyer flask deformities
  • Erlenmeyer flask deformity
  • Erlenmeyer flask deformity (EFD)

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Cases and figures

  • Figure 1: photograph - Erlenmeyer flasks
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  • Osteopetrosis
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  • Gaucher disease
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  • Pyle disease
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  • Rickets
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  • Pure red cell aplasia
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  • hereditary multiple exostoses
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