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Acromial types

Dr Aditya Shetty and Dr Frank Gaillard et al.

The shape of the acromion had been initially divided into three types (which was known as the Bigliani classification 3), to which a fourth has been added 2.


Acromion morphology based on sagittal oblique MRI:

  1. flat inferiorly
  2. curved
    • parallel to the humeral head with concave undersurface 
    • considered most common type 3
  3. hooked
    • most anterior portion of the acromion has a hooked shape
    • associated with increased incidence of shoulder impingement
  4. convex (upturned)
    • most recent classification of acromion process shape
    • the undersurface of the acromion is convex near the distal end 4
    • no convincing correlation between a type 4 acromion and impingement syndrome exists 4, 5

See also

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