My Shoulder is Separated, Do I Need Surgery? Injuries to the Acromioclavicular (AC) Joint

Football players, hockey players, and cyclists know all about these injuries: how they happen, how the shoulder looks… But there is something confusing about shoulder separations: no one really seems to know which person will be able to cope with the effects of the injury and who will be unhappily seeking for a shoulder surgeon to fix the problem.

Bones and Ligaments at the AC Joint

The best analogy I have heard to describe this part of the human body in lay terms is as follows. As you probably know, there is a bone in the center of the front of the chest called the sternum. The right and left collarbones project off the top of the sternum the same way the wings of an airplane project from the body of the plane. The shoulder blade and rest of the arm are pretty much hanging off the clavicle with the assistance of a number of muscles.

The suspensory complex of the shoulder

Take a closer look at the very end of the collarbone. It is connected to the shoulder blade two different ways: to the acromion bone, and to the coracoid bone. A first set of ligaments (acromioclavicular ligaments or AC ligaments) connect collarbone and acromion; they mostly keep them lined up so that the acromion does not move forward. The ligaments between the undersurface of the collarbone and the coracoid (coracoclavicular ligaments or CC ligaments) are responsible for holding the weight of the arm so that it does not hang down.

The acromioclavicular (AC) and coracoclavicular (CC) ligaments

How do these injuries happen?

Most of the time, shoulder separations occur as a person lands on the top of the shoulder by accident. For example, someone may fall over the handles of a bicycle and hit the their shoulder on the ground. The fall tends to separate the shoulder blade from the collarbone (hence the term “shoulder separation”).

Various types of AC joint injuries: types I, II, and III

If the injury is minor, the AC ligaments are sprained but nothing is really torn; this is a type I injury. With a more substantial injury, the AC ligaments get completely torn, but the CC ligaments are still intact (type II injury). A really bad accident will tear both the AC and the CC ligaments, and that is when the separation is really noticeable (type III injury): as the shoulder blade falls down and forward, the skin over the collarbone gets tented. It looks like the collarbone is sticking up, but what actually happens is that the whole shoulder blade is hanging low and forward, pulled by the weight of the whole arm. There are a few more uncommon complex patterns of injury (IV, V and III).

How to come back from a shoulder separation with no surgery

Individuals with a type I or type II injury almost always recover fully without surgery, and in fact, without much treatment. The use of a sling for comfort, occasional application of ice, and taking acetaminophen or non-steroidal anti-inflammatory drugs are all that is needed. Symptoms resolve within a few days in type I and in a few weeks in type II injuries. Occasionally, the articular surface of the AC joint is damaged in these injuries as well, creating the possibility of progressive arthritis with time.

Radiographs and deformity after a type III separation

Type III injuries can be more problematic. Without surgery, the deformity never improves, since the torn ligaments never heal. However, some individuals will adapt to their injury, and once the initial pain and swelling subsides, other than the deformity, they do not experience pain or other limitations. The key to a good recovery from a type III injury is to improve the strength and coordination of a number of muscles that support the shoulder blade (trapezius, rhomboids, and serratus anterior). If you think about it, when the ligament connections between the collarbone and the shoulder blade is permanently torn, the muscles connecting the trunk and chest to the shoulder blade will feel overstretched. That is why many individuals with a type III injury will complain mostly of neck pain, back pain, and pain around the shoulder blade. Concentrate on physical therapy exercises, specifically developed for the shoulder blade muscles, and you will likely recover better, despite the permanent cosmetic deformity.

If that is not enough…

Certain individuals will end up not doing well without surgery. In our experience, this is more likely to happen to people that ride bicycles or motorcycles on a regular basis, individuals who need to work with their hands overhead constantly (i.e., painters), and those who are just not able to recover good balance and strength in the muscles around the shoulder blade (this is called scapular dyskinesis, [scapula = shoulder blade; dys = poor; kinesis = movement]).

Reconstruction of the AC joint: Weaver-Dunn and tendon graft

There are multiple techniques described to reconstruct the stability of the AC joint. Our preference is to combine two of them. First, a vestigial ligament called coracoacromial ligament can be detached from the acromion and reattached to the end of the collarbone (this was described by Drs. Weaver and Dunn). Second, a tendon graft from a cadaver donor is used to create a new ligamentous connection between the coracoid and the clavicle, and sometimes over the acromion as well. After surgery, typically patients are required to use a shoulder immobilizer for six weeks. Therapy starts at that point. Most patients recover within 3-4 months after surgery.