ACJ Shoulder Injuries (collarbone)
The collarbone or clavicle is the strut that links the arm to the torso. It forms a joint with part of the shoulder blade or scapula known as the acromion (acromioclavicular joint or ACJ). Injuries to the ACJ are common and frequently result from a fall onto the point of the shoulder. Fortunately, most injuries constitute nothing more than a sprain of the ACJ (Grade I injury) and symptoms will settle with rest. Applying ice during the acute phase and use of anti inflammatories may help with the healing process.
More significant trauma to the joint can give rise to complete disruption of the joint (Grade III injury). Such an injury results from a complete tear of the stabilising ligaments passing between the clavicle and scapula. Once the initial discomfort has settled, individuals may in fact be relatively pain free as the two bones are no longer in contact. However, they are left with a prominence or step at the site of the injury that might prove unsightly. For some, the bone ends will catch from time to time causing pain and these are the two commonest reasons why some will seek advice. A reconstruction of the ACJ is a common procedure. It involves repositioning and stabilising the clavicular end of the joint by means of a ligament transfer often reinforced with an artificial ligament. Depending on individual circumstances (occupation, sporting activities) surgery may be appropriate in the acute phase.
A Grade II injury constitutes a partial displacement of the joint. The ACJ may be normal in appearance, but as the two bone ends frequently catch, painful clicking sensations are common. Symptoms may settle for an injection of the joint, although in some surgery to remove a small piece of the clavicle is necessary.
Arthritis of the ACJ is very common. This is perhaps not surprising given the different planes of movement about which the clavicle moves and the loads passing through the joint. Unlike the pain of subacromial impingement, discomfort is typically more localised over the top of the shoulder (over the ACJ). Symptoms may respond to an injection of the joint. If not, arthroscopic day case surgery to shave away a small section of the clavicle is usually curative.