Acromioclavicular Joint (ACJ) Injuries:
Causes, Symptoms & Treatment by Mr. David Shields
The acromioclavicular joint (ACJ), commonly called the AC joint , is located at the top of your shoulder where your collarbone (clavicle) connects with your shoulder blade (scapula). This joint plays a vital role in facilitating smooth and extensive shoulder movement. A “separated shoulder” often refers to an ACJ injury. These injuries are common, particularly among athletes participating in contact sports like rugby. However, anyone can experience an ACJ injury, even from a simple fall.
Understanding Acromioclavicular Joint Injuries: What is a Separated Shoulder?
An acromioclavicular joint injury, also known as a shoulder separation, occurs when the ligaments supporting the AC joint are damaged or torn. The severity can range from a mild sprain to a complete dislocation of the joint.
Common Causes of and Risk Factors for ACJ Injuries
The most frequent cause of an ACJ injury is a direct blow to the shoulder or a fall onto the shoulder. This is a common occurrence in sports like cycling and skiing, where falls are more likely. Participants in contact sports (e.g., rugby) are also at high risk due to the forceful impacts experienced during tackles and collisions. These are the common risk factors associated with ACJ injuries.
Recognising the Symptoms and Presentation of an ACJ Injury
The symptoms and presentation you experience will depend on the severity of the injury. Typical signs of an ACJ injury include shoulder pain located over the AC joint, which might radiate to your neck or down your arm. You may also experience tenderness specifically when you press on the pain over AC joint, as well as swelling in the area surrounding your shoulder. A noticeable bump or “step deformity” on the top of your shoulder can indicate a deformity of the shoulder. Finally, limited shoulder movement, making it difficult to move your arm freely, is another common symptom.
How Doctors Diagnose ACJ Injuries
Doctors diagnose ACJ injuries using a combination of methods. A physical examination will be performed, where the doctor will check for points of tenderness, swelling, and any visible deformities. X-ray imaging helps the doctor visualise the AC joint and determine the extent of the injury, including the degree of ligament damage and bone displacement.
ACJ Injury Classification: Understanding the Severity
ACJ injuries are classified into six types, using the Rockwood Classification, based on the severity of ligament damage and the extent to which the collarbone has moved out of place. Type I involves a mild sprain of the AC ligaments. Type II indicates a complete tear of the AC ligaments. Type III signifies a complete tear of both the AC and the coracoclavicular (CC) ligaments, resulting in a noticeable displacement of the clavicle. Types IV, V, and VI represent increasingly severe injuries, with greater displacement of the clavicle and involvement of surrounding soft tissues.
Treatment Options for ACJ Injuries
The appropriate treatment for an ACJ injury is determined by the severity of the injury and your individual circumstances.
Non-Surgical Treatment for ACJ Injuries
Type I and II injuries, and even many Type III injuries, can often be managed effectively without surgery. This typically involves rest, which means avoiding activities that strain your shoulder and allowing the ligaments to heal. Applying ice packs to the injured area helps reduce pain and swelling. For pain relief, you can use over-the-counter painkillers, or, if needed, your doctor may prescribe stronger pain medication. Wearing a sling helps support your shoulder and restrict movement, which is essential for ligament healing. Finally, once the initial healing phase is over, physiotherapy will involve exercises guided by a physiotherapist to restore strength, flexibility, and full range of motion in your shoulder.
Surgical Treatment for ACJ Injuries
Surgery is generally considered for the more severe Type IV, V, and VI injuries. It may also be recommended for Type III injuries that haven’t improved sufficiently with non-surgical treatment. Surgical procedures for ACJ injuries include Open Reduction and Internal Fixation (ORIF), where the surgeon realigns the bones and then uses plates, screws, or other implants to secure them in the correct position, stabilising the joint while the ligaments heal. Ligament Reconstruction may be necessary if the ligaments are severely damaged. This involves using a graft, taken from another part of your body (autograft) or from a donor (allograft), to replace the damaged ligaments.
ACJ Injury Recovery Time
The time it takes to recover fully from an ACJ injury depends on several factors, including the severity of the injury and the type of treatment you receive. If your injury is managed non-surgically, it might take several weeks to a few months for you to regain full function. After surgery, recovery typically takes several months. You’ll need to wear a sling for a period and then gradually start physiotherapy exercises to rehabilitate your shoulder. Returning to sports and other demanding activities may take six months or longer.
Frequently Asked Questions About ACJ Injuries
What’s the difference between a shoulder separation and a shoulder dislocation?
A shoulder separation is an injury to the ACJ, where your collarbone meets your shoulder blade. A shoulder dislocation involves the glenohumeral joint, the ball-and-socket joint where the top of your arm bone fits into the socket in your shoulder blade.
How long does it take for an ACJ injury to heal?
The healing time depends on the severity. Minor sprains might heal in a few weeks, whilst more severe injuries requiring an operation can take several months.
Will I need an operation for my ACJ injury?
Not all ACJ injuries require surgery. Many people, including those with Type III injuries, recover successfully with non-surgical treatments. Your doctor will assess your individual case and recommend the best course of action.
When can I return to sport after an ACJ injury?
The return to sport depends on the severity of your injury and the type of treatment you’ve had. It’s crucial to follow your doctor’s or physiotherapist’s guidance regarding returning to activity. They will help you gradually increase your activity level to ensure proper healing and prevent re-injury.
