Acromioclavicular Joint (ACJ) Injury

What is it?

The acromioclavicular joint (ACJ) is the small bony lump on the top of your shoulder. It’s where the collarbone (clavicle) meets the top part of the shoulder blade (acromion). Several ligaments hold the joint in place.

Over time, the bones of the joint can wear out, become larger, and develop spurs around the joint. This can then result in a degenerative disease known as osteoarthritis. The diseased bone can then cause damage to the joint ligaments. The cushioning membrane within the joint known as the bursa can also become inflamed and thickened, causing pressure and restricting movement.

Why does it occur?

People who use their arms for extended periods of time (especially overhead lifting) are susceptible to ACJ arthritis. Another cause is previous injury, such as an ACJ dislocation. Any activity that puts pressure on the joint may increase the chance of developing arthritis. These activities include swimming, throwing and racquet sports.

What are the symptoms?

You may notice a weakness in the upper arm and an aching pain on performing overhead activities. There may also be swelling in the joint as it is used. This can disrupt sleep, especially if you turn to lie on the affected shoulder.

How is it diagnosed?

X-rays will show the degeneration of the bone. An MRI scan may be used to rule out or highlight other problems including tendon or ligament tears. Arthroscopic diagnosis will clearly show whether you have degeneration of the bone.

How is it treated?

Non-surgical

Plenty of rest, pain relief and modification of activities can alleviate symptoms. If the pain continues with restricted function, the next step would be a steroid injection into the joint. This can be very effective in relieving pain as the hydrocortisone acts as a powerful anti-inflammatory. Following an injection, the joint should be rested for 24 hours and the sticky plaster should remain on to prevent anything from entering the injection site.

Surgical

Following a routine shoulder arthroscopy, a shaver is introduced into the sub acromial space. If there is osteoarthritis in your acromioclavicular joint (ACJ), it is necessary to shave the end of the collarbone (clavicle). This is called acromioclavicular joint reconstruction. During the surgery, the thickened cushioning tissue (bursa) is removed, and any badly damaged ligaments will also be removed. The last 1cm of the collarbone will be cut off, and any bone spurs or diseased bone will be trimmed and smoothed out. The surgery is done with an anaesthetic block to numb the arm. You can be awake during the operation or have some sedation to make you sleepy. As the operation uses water to see inside the joint, the wounds will leak some fluid which will be absorbed by cotton wool dressings. These dressings are removed a few hours after surgery (See Understand video – Distal clavicle resection). Following this you will see a physiotherapist who will give you some exercises to do, and you can then go home the same day.