Symptoms. Acromioclavicular (AC) Joint Separation

Classification of AC Joint Separation

Doctors use the Rockwood Scale to grade AC joint injuries from 1 to 6. They are classified according to how much damage the ligament sustains and the amount of space that exists between the clavicle and the acromion process. 

• Grade 1: This is a simple sprain to the AC joint. The ligament sustains only minor damage, and the bones are not separated.
• Grade 2: The AC or acromioclavicular ligament is torn in this injury.
• Grade 3: In this injury, the AC ligament and the acromioclavicular or coracoclavicular ligaments are ruptured. It often results in the collarbone being forced upward out of place.

From this point on the Rockwood Scale, the degree of injury depends on the collarbone’s displacement (clavicle).

• Grade 4: In this AC joint separation injury, the collarbone is forced backward or is displaced posteriorly.
• Grade 5: Superior displacement occurs in this AC joint separation injury, similar to a grade 3 injury but more severely. The space between the bones may be 3 to 5 times greater than normal. A step displacement may be seen in grade 3 to 5 injuries. 
• Grade 6: This AC joint separation injury occurs when there is a complete rupture of both the coracoclavicular and AC ligaments, and the collarbone (clavicle) is displaced downward (inferiorly).

AC Joint Separation Symptoms

The symptoms of an AC joint separation vary according to the extent of damage sustained. If the ligament has been sprained, the joint may be mildly tender. A complete separation or rupture is likely to be accompanied by intense pain as a symptom of AC joint separation. Swelling typically occurs with injuries greater than Grade 2, and bruising may occur several days after the injury occurs.
Sometimes in a grade 3 AC joint separation injury, people feel a sensation like a “popping.” It happens due to a shifting in the loose joint. AC joint separation injuries more severe than Grade 2 typically cause a noticeable deformity in the alignment of the shoulder or collarbone.

AC Joint Separation Diagnosis

If your physician suggests an AC joint separation injury, you will be asked about your trauma. In addition, the healthcare provider will pay attention to your past medical history. It will probably include any information about past accidents or injuries involving your shoulder. The healthcare provider will also ask you about your pain related to your AC joint separation to make a proper diagnosis.
Additionally, the doctor will most likely feel your shoulder joint and collarbone and check your movement. It may be painful, but in order to make an accurate assessment and diagnosis, your doctor will need to know about your pain and movement.
To diagnose AC joint separation, your physician may recommend X-rays. They can detect a problem in the AC joint and show if your collarbone is fractured. You may be asked to hold a weight in your hand to put stress on your joint while the X-rays are taken. The last will test the stability of a joint.

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