AC joint degeneration, also known as AC joint arthritis, is a common cause of shoulder pain as we get older. Apart from simple treatment, a cortisone injection into the joint can help with pain and function of the shoulder.

What is the acromioclavicular joint? 

AC joint anatomy

The acromioclavicular joint is found at the top of the shoulder. It joins the collar bone (clavicle) with the top of the shoulder bone (acromion). The joint is also kept together by strong ligaments between the collar bone, acromion, and 1st rib. Degeneration of the AC joint occurs with age as the joint space narrows and the cartilage wears away. Also, trauma to the joint can occur after a fall on the shoulder or a hit during contact sport. This trauma can also lead to early AC joint degeneration and arthritis.

AC joint arthritis is different to shoulder joint arthritis, which affects the ball and socket joint. Not only are these two conditions are different in anatomical terms. There are also significant differences in symptoms and treatments.

Symptoms of AC joint degeneration

AC joint pain is common. Often, patients point to the AC joint as the site of pain. Lying on the shoulder at night can be painful. Moreover, specific movements such as moving your arm across your body can recreate the pain. The joint may look swollen and is often tender to touch. Also, other tests such as shoulder strength and neck movements are usually normal.

Often, X-rays show typical arthritis changes of narrowed joint space and bony spurs. Ultrasound and MRI can also help if the diagnosis is uncertain.

Treatment of Acromioclavicular joint degeneration

Overall, treatment depends on how severe the symptoms are and the presence of other shoulder problems such as rotator cuff tears.

In mild cases, anti-inflammatory tablets such as ibuprofen and physiotherapy to strengthen the shoulder can help. Manual therapy and postural correction provide benefits. Also, a cortisone shot into the AC joint can help with shoulder pain.

In severe cases that fail conservative measures, surgery may be needed. Generally, surgeons perform keyhole surgery to remove the end of the clavicle to open up the joint. Removing the bone allows for normal movement without the bones rubbing together.

More on AC joint injections 

cortisone injection AC joint

A cortisone shot into the AC joint is effective at relieving pain by reducing inflammation and swelling. You can perform injections in either sitting on lying. The doctor directs a needle with a small syringe containing cortisone and local anesthetic into the joint. Sometimes, entry into the joint can be difficult because of narrowed space. Using ultrasound makes AC joint injections easier and more accurate. This increases the effectiveness and reduces side effects such as skin thinning.

Also, pain relief after an AC joint injection confirms the joint as the cause of pain.

AC joint injection side effects

Generally, a cortisone shot in AC joint is well tolerated. However, possible cortisone injection side effects include skin depigmentation, cortisone flare, and infection. Also, you should avoid repeated injections into one joint over a short period of time (3-6 months).

Final word from Sportdoctorlondon about AC joint degeneration 

All in all, Acromioclavicular joint arthritis is a common but underappreciated cause of shoulder pain in active people. Generally, a careful examination can confirm the diagnosis. Typically, a cortisone injection into the AC joint is a great way to confirm a diagnosis and help with rehab.

Other common shoulder conditions:

Dr. Masci is a specialist sport doctor in London. 

He specialises in muscle, tendon and joint injuries.

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