Acromial apophysiolysis

Last revised by Dr Daniel J Bell on 24 Feb 2019

Acromial apohysiolysis is a finding on shoulder MRI that may be encountered in patients with an unfused acromial apophysis. It is associated with athletes in throwing sports.

Presents with superior shoulder tenderness in a patient <25 years old, often in a young throwing athlete (~100 pitches/week in American baseball). May clinically mimic a shoulder labral tear.

Repetitive stress across a meta-acromion-meso-acromion type unfused acromion. The injury is analogous to epiphysiolysis at incompletely fused growth plates.

  • STIR / PD FS
    • increased signal intensity across an unfused acromion
    • STIR sequence is useful to avoid inhomogeneous fat suppression
  • T1
    • decreased signal intensity across an unfused acromion

Patients are usually treated conservatively, with rest and NSAIDs.

It is associated with an eventual os acromiale formation (86% vs. 4% control) and rotator cuff tear (after age >25 years) if the cause of the shoulder stress is not discontinued.

  • in a throwing athlete with shoulder pain, edema signal intensity across an unfused acromial apophysis, and no other cause for shoulder pain consider acromial apophysiolysis

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