ACROMIAL APOPHYSIOLYSIS OR APOPHYSITIS MRI FINDINGS

• Acromial apophysiolysis or acromial apophysitis is a Stress injury due to repetitive traction injury at the acromial apophysis.

• It results in instability at the apophysis and shoulder pain.

• People who have acromial apophysitis have a higher incidence of eventually developing an Os Acromiale.

• The acromion develops from 3 apophyses which progressively fuse by age 25.
  
  

•  <25yo unfused apophysis is normal but there should be no bone marrow oedema around the apophysis.
  
  

•  If >25yo and apophysis is unfused unfused = Os Acromiale. (Discussed this and how to find it in a previous post you can see HERE

• The apophysis has to be unfused.
   
• Oedema on both sides of the apophysis.
   
• +/- Cystic type change and cortical irregularity subjacent to growth plate.

• It's normal to see an unfused apophysis until 18-25yo.

• But there should be no oedema, cortical irregularity or subcortical cyst formation.

• If present, these are signs of instability and apophysiolysis.

See the images below for what the MRI appearance of Acromial Apophysiolisis looks like.