Acromiohumeral interval

Last revised by Yuranga Weerakkody on 03 Dec 2022

Acromiohumeral interval is a useful and reliable measurement on AP shoulder radiographs and when narrowed is indicative of subacromial impingementrotator cuff tear or tendinopathy. 

The shortest distance is measured. 

  • true AP shoulder radiograph
  • measure from the cortical bone at the inferior aspect of the acromion to the humeral head 3
  • can also be performed on coronal and sagittal oblique T1 MR images
  • inferior aspect of the acromion (marked by black line directly above the humeral head) directly inferiorly to the center of the subchondral cortex of the humeral head 3

Measurements of the acromiohumeral interval in the following intervals are suggestive of pathology 1,2:

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Cases and figures

  • Case 1: normal measurement
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  • Case 2: normal
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  • Case 3: reduced in chronic rotator cuff tear
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  • Case 4: increased in lipohemarthrosis
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