Alpha angle (developmental dysplasia of the hip)

The alpha angle is a measurement used in the ultrasonographic assessment of developmental dysplasia of the hip (DDH).

The angle is formed by the acetabular roof to the vertical cortex of the ilium and thus reflects the depth of the bony acetabular roof. This is a similar measurement to the acetabular angle.

The normal value is greater than or equal to 60 degrees. Less than 60 degrees suggests dysplasia of the acetabulum.

The term alpha angle is also used in a separate and unrelated context in the evaluation of femoroacetabular impingement.

See also

Imaging in practice

Article information

rID: 2725
Synonyms or Alternate Spellings:
  • Alpha angle (DDH)

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Cases and figures

  • Case 1: normal infant hip ultrasound
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  • Case 2: with developmental dysplasia of the hip
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