The acromio clavicular joint is the joint between the clavicle and the flat bone known as the acromion, which is part of the scapula. This joint forms part of an arch of bone above the rotator cuff muscles. It is not uncommon to develop wear and tear changes in the acromio clavicular joint. This causes the space in the joint to be decreased and the formation of spurs on the under surface. These spurs pinch the rotator cuff tendons with certain movements of the shoulder. This is very similar to the impingement caused by spurs developing on the under surface of the acromion.
WHAT IS THE CAUSE OF ACROMIO CLAVICULAR JOINT ARTHRITIS?
The most common cause of acromio clavicular joint arthritis is over use. It is common in rugby players and people who place a lot of stress on this joint. It often affects weight lifters and wrestlers. Injury to the joint can lead to osteoarthritis as can repetitive overhead activity.
WHAT ARE THE SYMPTOMS?
The symptoms are of pain over the top of the shoulder. The pain is made worse with activities above shoulder level. Reaching across to the opposite shoulder is particularly painful.
HOW IS THIS DIAGNOSED?
The diagnosis is usually made by a good history, examination and taking plain x-rays. Selective injection of local anaesthetic into the acromio clavicular joint can relieve the pain and confirm the diagnosis. Very rarely MRI scans with a dye may be necessary to see if there are any other problems.
WHAT IS THE TREATMENT?
In the early stages ice, rest and avoidance of overhead activities can be beneficial. Anti-inflammatory medication helps during the acute phase as can targeted exercises by your physiotherapist. The aim of the physiotherapist is to build the rotator cuff muscles, which then push the ball and socket joint downwards creating, in effect, more space. It is always important to try these conservative measures before considering surgery.
If conservative measures fail then surgery is indicated. The aim of keyhole surgery is to remove the cause of impingement. A small centimeter hole is made at the back of the shoulder to introduce a telescope into the subacromial space. Initially any scar tissue that has formed here because of the inflammation and part of the sac known as the bursa is removed. This is done using an instrument known as a vaporiser, which burns this tissue away. Following this a shaver is introduced to take away the excess bone at the acromio clavicular joint. This increases the space and removes the causes of impingement.