Graf method for ultrasound classification of developmental dysplasia of the hip

The Graf method for ultrasound classification system for developmental dysplasia of the hip (DDH) in infants, combines both alpha and beta angles. There are a number of additional subdivisions, which are often not used clinically. 

As a general rule, the alpha angle determines the type and in some instances, the beta angle is used to determine subtype:

  • type I: alpha angle >60 degrees (normal)
    • type Ia: beta angle <55 degrees
    • type Ib: beta angle >55 degrees
  • type II
    • type IIa: alpha angle 50-59 degrees (less than 3 months)
    • type IIb: alpha angle 50-59 degrees (greater than 3 months) 
    • type IIc
      • alpha angle 43-49 degrees
      • beta angle 70-77 degrees
  • type D ("about to decenter")
    • alpha angle 43-49 degrees
    • beta angle >77 degrees
  • type III: alpha angle <43 degrees
    • type IIIa and IIIb distinguished on the grounds of structural alteration of the cartilaginous roof
  • type IV
    • alpha angle < 43 degrees
    • dislocated with labrum interposed between the femoral head and acetabulum
    • inverted labrum

History and etymology

Both the beta angle and the alpha angles were originally described by R Graf in 1980 1


Ultrasound - general index
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Article Information

rID: 2724
Synonyms or Alternate Spellings:
  • Sonographic classification of development dysplasia of the hip (DDH)
  • Sonographic classification of developmental dysplasia of the hip
  • Ultrasound classification of DDH
  • Ultrasound classification of developmental dysplasia of the hip (DDH)

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Cases and Figures

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    Case 1: Graf type I hip ultrasound
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