The AC joint, or acromioclavicular joint, is the junction where the clavicle, or collarbone, attaches to the shoulder blade. This joint is a small bump that can be felt over the top of the shoulder.
The AC joint can undergo degeneration (wear and tear) over time, especially in people who do a lot of overhead work. This is known as AC joint arthritis and is common in middle age.
Arthritis or degeneration at the AC joint is usually felt as pain at the end of the collarbone or generalized soreness in the front and top of the shoulder.
Although AC joint problems can usually be diagnosed by a careful clinical examination, X-rays are also useful to evaluate the joint. In arthritis, bone spurs (spiny projections from the bone) and narrowing of the joint is seen.
AC joint arthritis can be treated with painkillers and anti-inflammatories, physiotherapy, and sometimes injections.
What does surgery involve?
In persistent cases, arthroscopic (keyhole) surgery may be done to excise the lateral end of the clavicle. The surgeon will remove the arthritis arthroscopically and widen the joint. This prevents the collarbone from contacting the shoulder blade and eliminates pain from the joint.