Acromioclavicular (AC) Sprains

Acromioclavicular (AC) sprains are also known as a shoulder separation. Unlike a true shoulder dislocation in which the humeral head is dislocated from the socket of the shoulder, in a more severe shoulder separation, the end of the clavicle is displaced relative to the adjacent acromion. 

There are six types of AC sprains (see table below). Grade 1-2 sprains are mild with no displacement of the AC joint and are usually treated without surgery including physical therapy, taping, NSAIDs, and activity modifications. Grade 4-6 are almost always treated with surgery to reduce the end of the collarbone back to its anatomic position and stabilize the AC joint. The AC joint is stabilized by both acromioclavicular and coracoclavicular (CC) ligaments. In grade 1-2 sprains, only the AC ligaments are injured, but in the higher-grade sprains, both the AC and CC ligaments are injured. If surgery can be scheduled within 3-4 weeks of the injury, an AC repair is the treatment of choice because the native ligaments may scar down and heal once the clavicle is back in the anatomic position; however, when AC sprains are more than 4 weeks old, then a cadaver graft is often required to help supplement the healing of the torn ligaments.


Ligaments injured

Position of clavicle relative to coracoid


AC ligament sprain

Anatomic (no displacement)


AC ligament tear

Anatomic (no displacement)


AC ligament tear, CC ligament sprain

25-100% Superior


AC and CC ligaments torn

Posterior to acromion


AC and CC ligaments torn

>100% Superior


AC and CC ligaments torn


  • Symptoms

  • Treatment


  • Localized pain to the top of the shoulder
  • Bruising over the top of the shoulder
  • Deformity with the collarbone sticking up
  • Pain with overhead reaching or lifting