AC Joint Injuries

Acromioclavicular joint injuries (or AC Joint injuries) occur at the top of your shoulder – between your clavicle (collarbone) and your scapula (shoulder blade). The AC joint is important in allowing overhead and across the body movements of your arm, as well as transmitting forces from the arm to the rest of the body during activities such as pushing, pulling and lifting. There are a number of ligaments which help to stabilise this joint.


AC Joint injuries refer to sprains – where the ligaments supporting the acromioclavicular joint are overstretched. The degree of AC joint ligament damage can vary from a mild strain of one or more of the surrounding ligaments to complete ligament tears and deformity.

When Grade 3 Acromioclavicular joint injuries occur, it is called a shoulder separation and can form a “step” if displaced. It is important to distinguish the difference from a shoulder dislocation, where the ball slips out of the shoulder socket. With an AC joint injury, the collar bone separates from the shoulder blade.

How do you know if you have an AC joint injury?

Your Leading Edge Physiotherapist will suspect an acromioclavicular ligament sprain when you report:
  • A history of impact to the shoulder that could damage the AC Joint ligaments (ie a bump on the side of the shoulder)
  • Pain on the top of the shoulder aggravated by heavy lifting, overhead and across body movements.
  • Swelling and/or bruising over the top of the shoulder
  • Loss of shoulder movement.
  • Sometimes a hard, visible lump may also be present on the top of the shoulder, indicating displacement of the collar bone in more severe cases

How do you treat AC joint injuries?

Depending on the severity of the injury, most patients with AC joint injuries start to feel better within a few days or a week of the injury. However, full ligament healing will take at least six weeks.

During this time it is important to protect your AC joint ligaments from over-stretching the immature scar tissue. It can be helpful to use a sling, taping or a shoulder brace that protects your AC joint.

Your Leading Edge physiotherapist will aim to:

  • Reduce pain and inflammation.
  • Normalise joint range of motion.
  • Strengthen your shoulder.
  • Improve your shoulder blade and shoulder alignment.
  • Normalise your muscle lengths.
  • Improve your upper limb proprioception/body awareness.
  • Improve your technique and function eg lifting, overhead activities.
  • Minimise your chance of re-injury as you return to sport or work.

I've just hurt my AC joint, what should I do right now?

To help resolve AC Joint Injuries as fast as possible:
  • avoid or modify activities and positions, which cause your pain. Recovery is easier if you stop irritating the shoulder.
  • rest your arm on a pillow when sitting for prolonged periods
  • use ice packs for 15 – 20 minutes regularly
  • hug a pillow or rest your arm on a pillow during the night.
Your next step is to have your AC joint injury assessed by a Leading Edge Physiotherapist. Contact us or book online today.