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On AC Joint Sprains (separated shoulder)


The AC (Acromio-clavicular) is a thick, fibrous joint that connects the top of the shoulder blade to the outer end of the collarbone. It’s required to be strong and supportive, and is the main way that weight bearing forces are transferred from the upper limb to the rest of the skeleton. The joint is connected by three strong ligaments: the Acromioclavicular, Coracoclavicular and Coracoacromial [as in the image below].


The main way this joint and its ligaments get injured is impact by a force that separates the shoulder away from the collarbone (usually in a downwards direction). This can occur from a fall where the top of the shoulder hits the ground first, a rugby tackle or a fall onto an outstretched hand. As with all injuries, there are many variations in severity and a grading system has been developed to classify AC joint injuries.


After an AC joint injury, there is usually immediate pain on the top of the shoulder, swelling and bruising. There is often loss of movement in the shoulder, and pain from putting weight on the arm, or carrying heavy objects. In severe cases, there is a visible lump on top of the shoulder, known as a ‘step deformity’, which is where an obvious difference in height can be seen between the top of the shoulder and the collarbone. Pain may be felt when reaching across the body, like when putting on a seatbelt.

To confirm the diagnosis, your physiotherapist can perform some clinical tests and an X-ray can help to grade the severity of the injury. The classification that would be given to you by your physiotherapist or doctor help determine the optimal course of action.

There are different classification systems, some use three grades and other six. Injuries with a smaller number of ligament fibres being torn are given a lower grade classification, going upwards as further damage is incurred. Injuries classified as higher grades will require surgical repair.


Your physio will be able to help ensure the joint is supported and given a chance to heal naturally, while maintaining the strength and normal movement of the shoulder girdle. They’ll do this initially by providing support to the joint. You may need to have your arm supported in a sling or brace for some of this time and your physiotherapist can show you some taping techniques to add support.

Most AC joint sprains take six weeks to fully heal, although many patients report shoulder problems in future years. For this reason, a comprehensive rehabilitation program is very important. More severe sprains are often treated with surgery to stabilise the joint and treat any possible fractures. Surgical repair will also require a proper rehabilitation program.

For more information, please contact Caboolture Physical Therapy Centre. Always see a medical professional for advice on your individual injury.

Caboolture Physical Therapy Centre – serving people in need from the following areas: Caboolture, Morayfield, Elimbah, Wamuran, Beerburrum, Beerwah, Glasshouse Mountains, Toorbul, Donnybrook, Ningi, Woodford, Kilcoy, Bribie Island, Goodwin Beach, Sandstone Point, Banksia Beach, Bongaree, Bellar, Woorim, Burpengary & Beachmere.


Kaye graduated from the University of Queensland in 1983 with a Bachelor of Physiotherapy. She worked in Canberra, Sydney, London, Lincoln and Redcliffe before starting her first practice in 1989. More about Kaye

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