Acromioclavicular Joint (AC Joint) Injury

AC Joint Injury is one of the more common upper body injuries seen in contact sports such as Aussie Rules Football or Rugby, as well as sports like cycling and motocross. It affects the joint where the Clavicle or ‘collarbone,’ meets the Acromion (or the prominent bony point of the shoulder). This Injury normally occurs when there is a strong force applied downwards on the clavicle causing a strain, tear or rupturing of the ligaments that surround this joint. Examples such as a strong bump with a downward force, being tackled and driven into the ground onto the point of your shoulder and sometimes landing on an elbow or outstretched arm can cause this injury. In severe cases, a moderate tear or rupturing of the ligament results in a noticeable ‘step deformity’ because the weight of the arm pulls it away from the clavicle. However, this will not necessarily affect the function of the arm and only in very severe cases will it require surgery to re-attach the ligaments around the joint.

Three main types of AC injuries:

  • Type I = local tenderness at the point of the shoulder and some movement of the joint. Some minor damage to the joint capsule and Acromioclavicular Ligament but no ‘step deformity.’ Approximately 2-3 weeks return to sport

  • Type II = More severe pain locally to touch and with movement of the joint. Minor to moderate ‘step deformity’ present. Partial/complete tear of the Acromioclavicular Ligament and some tearing of the Coracoclavicular Ligament. Minimum of 4-6 weeks before return to sport.

  • Type III = Moderate to severe ‘step deformity’ and severe pain and discomfort throughout the shoulder. This occurs when there is complete rupturing of the two ligaments. Sometimes surgery is required for this type of injury. Approximately 8-10 weeks minimum before returning to sport.


  • The first step in the rehab process is to reduce the swelling, and inflammation of the area but applying ice, compression and offloading the shoulder joint as often as is comfortable/able. A sling may also be prescribed to immobilise the joint in serious cases.

  • Potentially if the injury is suspected to be quite severe the person may be sent for a scan to see the exact extent of the damage to that joint.

  • Once the pain is settles, a gentle range of motion program and a graded strengthening exercise program for the global muscles and the rotator cuff in order to support the injury joint will be outlined.

  • Only in severe circumstances will surgery be required.

Return to Sport:

(in order to return to sport we must be able to tick all of these boxes)

  • The range of motion is to an acceptable level for that specific sport

  • Pain levels are at a manageable level throughout the range of motion and not affecting the function/biomechanics of the shoulder or rest of the body

  • Minimal risk of further injury is expected if the worst case scenario of another injury was to happen

  • Coaches, support staff and physiotherapist give the ok

As always, getting a thorough assessment and understanding of the injury is advised. Check in with your health professional as soon as possible if you suspect you have injured your AC joint so that you can get started with your recovery immediately.

Do you have any aches or pains that you want to get checked out? Book in online here to see one of our Physio's today, or call us (08) 9448 2994.

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