What is Acromioclavicular (AC) Joint Injury? 

Acromioclavicular joint injuries relates to the joint between the collar bone and the pointy protrusion of your shoulder blade on the outer edge of your shoulder. Two ligaments that can be involved in this injury depending on the severity are the acromioclavicular and coracoclavicular ligaments. Type I and II AC joint injuries are when these ligaments are sprained or stretched however, type III is when these ligaments are ruptured and the AC joint is dislocated.

Signs and symptoms

  • Pain on the outer edge of the shoulder
  • Swelling and bruising on the outer edge of the shoulder
  • Step deformity on the outer shoulder
  • Movements that may aggravate you will be across the body movements such as putting on your seat belt

What causes it? 

AC joint injuries are caused by direct or indirect trauma to outer part of the shoulder. Examples of direct impact include falling on the shoulder or someone / something colliding with the outside shoulder. Indirect traumas are less common and occur when you fall onto an outstretched arm.

Conservative treatment

  • Graded exercise. In the early phases of rehabilitation of your shoulder the goal is to gain full range of pain free movement. Towards the end of the rehab the goal is to progressively strengthen the shoulder starting with closed chain exercise ,moving towards open chain and end of range activity and strength. The aim is to return to normal activities of daily living.
  • Taping/Bracing. On assessment of your shoulder your physiotherapist will determine if you require a sling with more sever AC joint injuries. Otherwise physiotherapy can offer taping to support and offload the AC joint while the tissue heals.
  • Ice. To ease pain and swelling in the acute stages.
  • Anti-inflammatory. Nonsteroidal anti-inflammatory drugs (NSAIDs), like ibuprofen, naproxen, or aspirin, will help with pain and swelling as per GP instructions.


In more severe grades of AC joint injuries and dislocation surgery may be recommended.