Ac Joint Tears

(Separated shoulder)


The acromio-clavicular (AC) joint is a thick fibrous joint, where the top of the shoulder blade articulates with the outer end of the collarbone. This joint is responsible for transferring most weight-bearing forces are transferred from the upper limb down to the rest of the skeleton. The Acromioclavicular, Corococlavicular and Corocacromial ligaments all help to stabilise the AC joint.


The most common culprit of an AC joint injury is excessive force, usually in a downward direction that separates the shoulder away from the collarbone. This can occur from various events, such as a fall where the top of the shoulder is the first to hit the ground, a tackle in a team sport or a fall onto an outstretched hand. Similarly to most other injuries, there are variation in the severity of the injury and thus there has been a grading system developed to classify AC joint injuries.


Common symptoms include:

  • Immediate pain on the top of the shoulder
  • Swelling
  • Bruising

There is often resultant loss of movement and pain when putting weight through the arm, such as moving heavy objects and reaching across the body, as such putting on a seatbelt.

  • In some cases there can be a visible lump on the top of the shoulder, know as a ‘step deformity’, where an obvious height difference can be seen between the top of the shoulder and the collar bone.

Your physiotherapist is able to confirm the diagnosis via clinical tests, and potentially an X-ray to help grade the severity of the injury. They will then utilise this diagnosis to optimise your treatment plan based on current evidence and available techniques.

Various difference classification systems exist, some use four grades and others six. Injuries where there are a smaller number of ligament fibres torn are given a lower grade classification, going upwards as further damage is incurred. Depending on the severity of the tear, some injuries will require surgical intervention.


The physio is able to determine a position that allows the joint maximal support, ensuring it is given a chance to heal naturally whilst maintaining the strength and normal movement of the shoulder girdle. They may initially place you in a sling or brace to help support the weight of your arm. The physio may also provide you with some taping techniques to further support the joint.

Most AC joint sprains take 6 weeks to fully heal, although it is common to experience problems in future years. For this reason it is important you complete the full recommended rehabilitation and strength program assigned by your physio. Whether the tear requires surgery or not a rehabilitation program is still required.

None of the information in this newsletter is a replacement for proper medical advice.

Always see a medical professional for advice on your injury.

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