Arthritis commonly affects the acromioclavicular joint, the small joint on top of the shoulder where the outer end of the collarbone meets the shoulder blade. It is usually shortened to the AC joint.
Symptoms
AC joint pain is not always well localised to the joint itself, which is one reason it can be mistaken for other shoulder problems. Pain is typically worse when lifting the arm overhead, and when reaching across the body. If the joint is arthritic there is often a tender bony lump over the top of the shoulder where the joint lies.
Because the joint sits directly under the skin, tenderness can usually be pinpointed with one finger, which helps distinguish it from rotator cuff pain felt further down the outer arm.
Treatment
Non-surgical treatment
Most AC joint pain will settle with rest and simple pain relief such as paracetamol or ibuprofen. If it does not, a cortisone injection can be placed into the AC joint, which can be done under ultrasound guidance to make sure it reaches the right place.
Surgical treatment
If symptoms from the AC joint do not settle, a resection procedure may be suggested. This is done as an arthroscopic (keyhole) operation. The procedure excises the AC joint, creating a larger joint space by removing a segment of bone at the end of the clavicle, so that the worn surfaces are no longer in contact. The space that is left fills with fibrous scar tissue, which takes the place of the worn arthritic joint.
As with any operation there are risks, including those of the anaesthetic, infection, and persistent or recurrent pain. These are discussed individually in consultation before any decision is made.
What to do next
If you have tenderness on the top of your shoulder that is worse reaching across your body, see your general practitioner. A referral is needed to claim the Medicare rebate for a specialist consultation.
This page is general information and is not a diagnosis. Individual circumstances vary, and the right treatment for you can only be determined after assessment. Any procedure carries risk; these are discussed in consultation.
