AC Joint Injury
A Common Cause of Pain at the Top of the Shoulder After Trauma or Overuse
The acromioclavicular (AC) joint is located where the collarbone (clavicle) meets the highest point of the shoulder blade (acromion). This joint helps stabilise your shoulder and allows you to lift your arm overhead. AC joint injuries are common in athletes and individuals who experience trauma to the shoulder. These injuries can range from mild sprains to complete separations, causing pain and limiting your ability to move the arm.
CAUSES OF AC JOINT INJURY
AC joint injuries are often caused by direct trauma to the shoulder or repetitive strain. Common causes include:
- Direct Impact or Trauma: A fall onto the shoulder, particularly with an outstretched arm, is one of the most common causes of AC joint injury. This can happen during contact sports like rugby, football, or cycling accidents.
- Repetitive Strain: Athletes who engage in sports that involve repetitive overhead motions, such as weightlifting, swimming, or tennis, may develop chronic AC joint problems over time. This type of injury typically results from the joint becoming irritated or inflamed due to overuse.
- Degeneration with Age: Over time, the AC joint can wear down, leading to osteoarthritis or degenerative changes that can make the joint more susceptible to injury. This can cause chronic pain and discomfort, particularly during activities that require shoulder movement.
TYPES OF AC JOINT INJURIES
AC joint injuries are classified based on the severity of damage to the ligaments that stabilise the joint. These are commonly referred to as “grades” or “types” of injury:
- Grade I (Mild Sprain): This involves a mild sprain of the AC ligament with no displacement of the clavicle. The ligaments are stretched but not torn.
- Grade II (Partial Separation): A partial tear of the AC ligament results in the joint becoming slightly unstable, with mild displacement of the clavicle.
- Grade III (Complete Separation): This occurs when both the AC and coracoclavicular (CC) ligaments are torn, leading to a complete separation of the clavicle from the shoulder blade. The shoulder may appear visibly deformed or “bumped.”
- Grade IV-VI (Severe Injuries): In more severe cases, the clavicle may be displaced significantly, either backward, downward, or through the muscle. These injuries often require surgical treatment.
SYMPTOMS OF AC JOINT INJURY
The symptoms of an AC joint injury can vary depending on the severity of the injury, but they typically include:
- Pain: Pain is often felt directly at the top of the shoulder, especially when moving the arm overhead or across the body. The pain can be sharp initially and may become more dull or aching over time.
- Swelling and Bruising: The area around the AC joint may become swollen and bruised following an injury, particularly after a direct impact.
- Limited Range of Motion: You may find it difficult to lift your arm or move your shoulder through its full range of motion. Reaching across your body or lifting objects overhead may aggravate the pain.
- Visible Deformity: In more severe cases, particularly with Grade III or higher injuries, you may notice a visible bump or deformity at the top of the shoulder where the clavicle has been displaced.
- Weakness: AC joint injuries can cause weakness in the shoulder, making it difficult to perform tasks that involve lifting or carrying objects.
DIAGNOSIS OF AC JOINT INJURY
When you consult with Dr Liddell, he will perform a detailed physical examination to assess the stability of your AC joint and the extent of your pain and mobility. Diagnostic tests may be recommended to confirm the diagnosis and determine the severity of the injury:
- X-Rays: X-rays are commonly used to assess the position of the clavicle and check for any fractures or dislocations in the AC joint.
- Ultrasound: In some cases, an ultrasound may be used to evaluate the soft tissues around the AC joint and detect any ligament damage or swelling.
- MRI: If the injury is more severe or if other structures in the shoulder are affected, an MRI may be recommended to provide detailed images of the joint and surrounding ligaments.
AC JOINT INJURY TREATMENT OPTIONS
Treatment for AC joint injuries depends on the severity of the injury and the degree of pain and functional limitation. In many cases, non-surgical treatments are effective, but more severe injuries may require surgical intervention.
Non-Surgical Treatments
For mild to moderate AC joint injuries (Grade I and II), non-surgical treatments are often successful in managing symptoms and restoring shoulder function.
These treatments include:
- Rest and Ice: Resting the shoulder and applying ice packs to reduce swelling and inflammation are often the first steps in treating an AC joint injury. Avoiding activities that aggravate the joint is key to preventing further damage.
- Activity Modification: Avoiding activities that put strain on your AC joint, particularly overhead motions, will give the ligaments time to heal.
- Medications: Over-the-counter anti-inflammatory medications, such as ibuprofen, can help manage pain and reduce swelling.
- Physiotherapy: Once the initial pain and swelling have subsided, a physiotherapy program can help restore your shoulder’s range of motion and strengthen the muscles around the AC joint. This is especially important for athletes returning to sport.
- Corticosteroid Injections: In cases of persistent pain, a corticosteroid injection may help reduce inflammation and provide pain relief.
Surgical Treatments
Surgery may be required for severe AC joint injuries (Grade III or higher) or for patients with ongoing pain and instability despite non-surgical treatment.
Surgical options might include:
- AC Joint Reconstruction: This involves repairing or reconstructing the torn ligaments to stabilise the AC joint. During the procedure, Dr Liddell may use screws, pins, or suture anchors to reattach the ligaments and realign the clavicle.
- Distal Clavicle Resection: In cases of severe AC joint degeneration or arthritis, the end of the clavicle may be surgically removed to reduce pain and improve function. This procedure, known as a distal clavicle resection, can alleviate pain caused by bone spurs and joint inflammation. By removing a small portion of the clavicle, this procedure aims to create more space in the AC joint, reducing friction and pressure on surrounding structures. It is typically performed arthroscopically or through a small open incision. AC joint injuries can significantly affect your ability to use your shoulder, especially for lifting or overhead movements. Whether caused by a traumatic event or repetitive strain, these injuries can be painful and limit your mobility. Early diagnosis and appropriate treatment are key to restoring shoulder function and reducing pain.