AC Joint Injury Causes, Symptoms & Treatment

AC Joint Injury: Causes, Symptoms, & Treatment

When you have an AC joint injury, it can be hard to figure out exactly what’s going on. And if you’ve ever had one of these injuries before, then you know how painful they are and that the pain can last for weeks or even months.

Your AC joint is a small bump on the top of your shoulder blade that connects your collarbone to your shoulder blade. It’s responsible for holding up most of the weight of your arm and providing stability for movement. If you have an injury or sprain to this area, it can be very painful and cause significant loss in function if not treated properly.

There are several different treatment methods for patients with AC joint injuries including shoulder physiotherapy, relief therapy, manual therapy and rehabilitation exercises designed to rehabilitate the injured area while reducing pain levels associated with these types of injuries.

It is also important to educate yourself on ways to avoid further injury through stretching and strength training techniques which can help prevent future issues related to repetitive use of this muscle group during sporting activities or everyday tasks like lifting heavy objects or using tools.

AC Joint Injury Causes, Symptoms & Treatment

To learn more about AC joint injuries, causes and treatments, please continue reading below as we explore this in more detail below.

What Exactly Is The AC Joint?

The acromioclavicular joint in the shoulder, or AC joint, is the point where the clavicle (collarbone) meets the acromion (hook of the shoulder blade). Several conditions can happen to the AC joint including arthritis, fractures and separations. 

AC joint arthritis is characterised by pain, particularly when it comes to overhead activity or compressive activities such as reaching across the body. The arthritic changes in the AC joint are evident on X-ray imaging.

The AC joint can also be injured by a blunt force impact often directly on the side of the shoulder, such as being tackled during rugby or football, or in a cycling accident. The degree of injury can be graded depending on the severity of the sprain suffered by the ligaments to complete the separation of the AC joint.

A specialised physiotherapist can help reduce your pain and the symptoms associated with AC joint injuries by utilising pain modalities, taping, manual therapy techniques, and an individualised exercise program of shoulder range of motion and strengthening exercises.  

If there is concern or diagnosis of a high degree of separation or irritable shoulder osteoarthritis then your physiotherapist will refer you to an orthopaedic specialist for an opinion on management.

AC Joint Injury Causes, Symptoms & Treatment

Do All AC Joint Injuries Require Surgery?

No, not all AC joint injuries require surgery. Surgery is indicated in advanced levels of AC joint separation and AC joint arthritis that does not respond well to physiotherapy management. 

How To Prevent An AC Joint Injury From Recurring?

To prevent an AC joint injury it is often necessary to find the specific reason contributing to the injury. If it is due to a lifting or pressing type of motion then it is often necessary to modify the activity. 

In addition, shoulder strengthening exercises can help to support the joint and prevent recurrence of the injury. In the case of a sudden trauma resulting in an AC joint injury, ensuring a return to sport at a suitable time after appropriate healing and rehabilitation is vital.

What Is Acromioclavicular Joint Separation?

Acromioclavicular separation occurs when trauma to the joint results in the tear of the capsule and ligaments around the joint. This usually happens as a result of falling on the tip of the shoulder. There are six different types of  AC joint separation based on the joint capsule and ligament tears and injury. 

  1. Type 1 injury is usually associated with a sprain of the capsule joint. The symptoms include local tenderness and pain on movement, especially crossing the arm in front of the body. 
  2. Type 2 injury: there is a complete tear of AC ligaments and some sprain of the ligaments further away from the AC joint. The symptoms include localised tenderness and a small palpable step deformity can be present. 
  3. Type 3-6 injuries: The supporting ligaments around the AC joint have been torn completely and an obvious step deformity is present. Types 3-5 are distinguished from each other based on the amount and direction of displacement. 

AC Joint Injury Causes, Symptoms & Treatment

The management of AC joint separation is dependent on the level of injury. Overall, for level 1 and 2 injuries the management consists of reducing pain and inflammation, resting from aggravating injuries and commencing range of motion and strengthening exercises as guided by your physiotherapist. 

For the level 3 AC joint injuries, management depends on several factors based on your individual circumstances and can be either conservative or surgical. Surgery is the treatment of the choice for Type 4 – 6 injuries, with post-operative specialised physiotherapy input.


The AC joint is one of the most important joints in your body. If it becomes injured, you will need to seek treatment before too long. Our blog post has provided some information about what an AC injury looks like and how to treat it so that you can recover quickly and with minimal pain. 

We hope this article was helpful for you! Should anything come up after reading our article, please feel free to contact us at any time. We’re here for all patients who have questions about any shoulder conditions!

Please call us at Melbourne Hand Therapy today (03) 9899 8490 or leave an enquiry and we will get back to you as soon as possible.

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