Shoulder and Elbow Surgery: "Shoulder Separation" or Collar bone dislocation

Shoulder Separation or Collar bone dislocation

Most patients have in mind the ball and socket mechanism of the shoulder when the word separation comes to their minds. A shoulder or collar bone separation is not an injury to the ball and socket mechanism of the shoulder. The injury refers to the acromioclavicular joint (also called the AC joint). The AC joint is where the collarbone (clavicle) meets the highest point of the shoulder blade (acromion). In most patients this is visible as a prominence on the skin, but not easily seen in overweight patients.

This figure shows the normal bony anatomy of the area. The separation happens between the clavicle and acromioclavicular (AC)joint.

How does this injury happen?

For the joint to separate there must be direct blow to the shoulder. This usually happens from a fall on the shoulder or during an impact to the shoulder area. It is commonly seen in football players and contact sport athletes.

The collabone displaces upwards because the ligaments that surround and stabilize the joint are torn. Depending on how severe is the damage to the ligaments there is displacement. Sometimes there is only pain in the area with minimal displacement. On occasions the collarbone displaces upwards significantly to the point that is not in contact with the articulating bone on the other side of the joint. Your doctor will determine how severe the displacement is based on the x-rays.
The collarbone has ligaments that attach to the shoulder blade. When the ligaments torn then the shoulder blade displaces downward because of the weight of the arm. This creates a "bump" or bulge on the top of the shoulder.

On the right side you can see the purple area where the collar bone separates while the weight of the arm brings the shoulder downwards.

This figure shows the intact ligaments around the acromioclavicular joint. The rAC ligaments arrow points to the ligaments that are around the joint itself. The CC ligaments arrow points out the important stabilizing ligaments underneath the collarbone.

What are the symptoms and the severity of the separation?
There might be moderate pain if the separation is not severe. Change in the configuration of the shoulder is seen sometimes over the skin. Occasionally, significant deformity will be seen and there will be a lot of pain in the area. It is important to understand that good pain-free function often returns even with a lot of deformity. The greater the deformity, the longer it takes for pain-free function to return.

A mild shoulder separation involves a sprain of the AC ligament that does not move the collarbone and looks normal on X-rays.
A more serious injury tears the AC ligament and sprains or slightly tears the coracoclavicular (CC) ligament, putting the collarbone out of alignment to some extent.
The most severe shoulder separation completely tears both the AC and CC ligaments and puts the AC joint noticeably out of position.

How will the doctor diagnose what I have?

The doctor will examine the shoulder, find the area of maximum tenderness and order X-rays. If there is deformity in the area from the doctor will evaluate the X-rays to tell you about the degree of the separation. Sometimes for the diagnosis an Xray is not necessary because the injury causes deformity. As highlighted above the Xray is necessary for classification of the injury and evaluating the degree of displacement. When there is less deformity, the location of pain and X-rays help the doctor make the diagnosis. Sometimes having the patient hold a weight in the hand can increase the deformity, which makes the injury more obvious on X-rays.

What is the best treatment for this injury?

Non-surgical Treatment

If the displacement is not severe then your doctor may suggest a non operative approach. This is usually a sling, application of cold packs and pain management. There are physicians who use complex braces for this injury, however there is no clinical trial to prove that they are better compared to a sling. Sometimes these braces provide better comfort but are expensive.

Most people return to near full function with this injury, even if there is a persistent, significant deformity. Some people have continued pain in the area of the AC joint, even with only a mild deformity. This may be due to:

Abnormal contact between the bone ends when the joint is in motion
Development of arthritis
Injury to a disk-like piece of cushioning cartilage that is often found between the bone ends of this joint

It is often worthwhile to wait and see if reasonable function returns without surgical treatment.

Surgical Treatment

Surgery can be considered if pain persists or the deformity is severe. A surgeon might recommend trimming back the end of the collarbone so that it does not rub against the acromion.

Where there is significant deformity, reconstructing the ligaments that attach to the underside of the collarbone is helpful. This type of surgery works well even if it is done long after the problem started.
Whether treated conservatively or with surgery, the shoulder will require rehabilitation to restore and rebuild motion, strength, and flexibility.

Examples of reconstruction of the AC joint are given with the pictures below. There are many different techniques. The hook plate has been introduced recently however it has complications and is still being evaluated by researchers. The disadvantage of a hook plate is that it needs to be removed at 6 months after the surgery.