AC Joint

What is it?

The clavicle (collar bone) is connected to the scapula(shoulder blade) by the AC joint. The joint can be felt on the superior and lateral aspect of the shoulder. The joint can be separated or fractured by a direct blow to the shoulder or a fall on the arm. The joint can also develop arthritis which may or may not be related to a previous injury.

What are the symptoms?

An AC dislocation or separation is not the same as a shoulder dislocation (link to that section here), which occurs at the glenohumeral (ball and socket) joint. With an AC joint injury, the superior aspect of the shoulder is swollen and tender. The clavicle may or may not appear prominent and the shoulder may have a droop compared to the other shoulder.

How is it evaluated?

The spectrum of injury is graded from one to six with Grade 1 being the least severe. This may be confirmed with an X-ray. In some cases, an MRI is also indicated.

How is it treated?

Often, all that is necessary is rest, ice, and medication to treat the pain and swelling. Activities are gradually increased over time. With a more severe injury, surgery may be recommended to reduce the joint and repair or reconstruct the torn ligaments. At times, the distal clavicle may also need to be removed. In some cases, the distal clavicle may remain prominent after it has healed, even though it is no longer painful.