AC Joint Injury/Separation

The AC joint is where the acromium (part of the shoulder blade) joins the clavicle (collar bone) and is usually the highest part of the shoulder.
Separation of these two bones is due to ligament damage. Most common onset of the pain is falling either onto the shoulder itself or onto an outstretched arm. There are grades from 1-6 for AC separation so you should get it checked out to see how bad the damage is.


  • Pain over the tip of the shoulder; at first the pain is diffuse but later becomes very focal.
  • A ‘step deformity’ may be visible; it is seen as a raised lump on the shoulder
  • Pain when raising the shoulder above shoulder height

Article about AC Joint Separation from ‘AboutOrthopedics’