AC Joint Pain

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Injuries to the AC joint are common and may be degenerative or traumatic. Most commonly as we age, bone spurs develop in the AC joint as a result of arthritis, and when it is symptomatic may produce a very typical pain for patients that is easy to diagnose via physical examination. Treatment may range from NSAID use to most commonly a cortisone injection.


In the rare patients that do not respond to cortisone injections, it is very simple to arthroscopically resect the AC joint. Additionally, trauma to this area (typically a fall directly onto the shoulder) most commonly results in disruption some of the ligaments.  In serious cases, many ligaments are torn: (as pictured to the left) which may also be reconstructed arthroscopically.  Most frequently, the injuries are not that severe and a period of rest and NSAID use will resolve the symptoms.

What (and where) is the AC Joint?

When we hear medics referring to the AC Joint, we might not always know what body part they are referring to – let us throw some light on the subject. The AC joint is found in the shoulder. The shoulder is made up of three bones, the shoulder blade, (also known as the scapula), the collarbone (clavicle), and the top part of the arm bone (humerus). The top part of the arm bone has a round head which fits neatly into the socket formed by the scapula and clavicle.  The end part of the scapula is known as the acromion and the acromioclavicular joint (AC joint) lies between the acromion and the clavicle. The shoulder joint is the most flexible joint in the human body and allows the greatest range of movement and flexibility of any body part. For this reason, it is often the subject of injuries and strains. It is very often overworked and normal wear and tear can result in pain and injuries which in later life can cause degenerative AC joint issues.

AC Joint problems

AC Joint pain can be caused by a shoulder injury to any part of this complex joint. A blunt or direct force can injure the joint as is often seen in football tackles. On the other hand sometimes it takes just a simple fall where the person stretches out their arm to save themselves. This can result in a blunt force impact and can lead to AC joint pain and damage. As mentioned above, day to day wear and tear can cause problems by simple overuse of the shoulder, either through sports, for example, baseball players with overhead movement, or a painter and decorator whose job involves repetitive overhead movement. Degenerative joint disease is a common complaint among this category of people as is AC joint arthritis.

What is acromioclavicular joint arthritis?

Arthritis, simply put, is an inflammation. Arthritis in the AC Joint is just that and is caused by, as described above, wear and tear of the joint and is a common type of shoulder arthritis. Footballers are subject to this common type of arthritis due to injuries sustained through the nature of the impact sport they practice, as are basketball players and baseball players due to the repetitive overhead movement involved in playing these sports. Arthritis in the AC joint can, however, be the result of age related wear and tear. Given the flexibility of the shoulder joint and the range of movements it allows us to carry out, it’s no wonder this type of arthritis is common in over 50 year olds.

Symptoms of AC Arthritis

Symptoms usually present with a pain on the top of the shoulder and will be more noticeable when lifting heavy objects, trying to lift arm overhead or across the body. Sometime swelling with or without bruising may be noticeable. The patient may notice a loss of movement in the shoulder or a reduction in mobility. If you notice any of these symptoms and the ac joint pain persists, you should see your medical practitioner.

What treatments are available for AC arthritis?

It really depends on the severity of the case and whether there are other problems affecting the shoulder.  Mild symptoms, which are not limiting arm mobility, might be treated with some physiotherapy together with anti-inflammatory medicines.   In some cases a cortisone injection can be administered. These would be considered the most basic measures and would be tried initially to help relieve pain and discomfort. If symptoms of AC joint pain do not seem to respond to this treatment or if the symptoms are deemed to be more severe upon assessment, surgery may be an option but will be carefully considered as an option with your reputable medical practitioner. If you are in the Seattle area why don’t you call in to Daniel Schwartz M.D. Shoulder surgeon surgeon where upon a simple physical examination you can get diagnosis and begin your treatment plan.