Acromioclavicular (AC) joint arthritis is a condition where the cartilage in the AC joint (located at the top of the shoulder where the collarbone meets the acromion of the scapula) begins to break down over time. This form of arthritis, also known as degenerative arthritis of the AC joint, can cause pain, stiffness, and limited movement in the shoulder. It is most commonly seen in people over 40 years old and those with a history of previous shoulder injuries.

Acromioclavicular (AC) Joint Arthritis: Causes, Symptoms, and Treatment

What is Acromioclavicular (AC) Joint Arthritis?

The AC joint is crucial for shoulder movement and stability. Over time, the cartilage that cushions the joint can wear down, leading to friction between the bones and causing inflammation. This condition is often a result of wear and tear(osteoarthritis), but can also be caused by injury, overuse, or genetic predisposition.

Causes of AC Joint Arthritis

The primary cause of AC joint arthritis is the degeneration of the cartilage within the joint, but it can also occur due to:

1. Repetitive Stress or Overuse:

   • Activities that involve repetitive overhead motions, such as throwing or lifting, can increase the wear and tear on the AC joint, leading to arthritis.

2. Previous Shoulder Injuries:

   • A history of shoulder injuries, such as an AC joint separation or fracture, can increase the likelihood of developing arthritis in the joint later in life.

3. Age-Related Changes:

   • Like other forms of osteoarthritis, AC joint arthritis is more common with aging as the cartilage naturally wears down over time.

4. Genetics:

   • Some individuals may be more genetically predisposed to developing arthritis in the AC joint, especially if there is a family history of osteoarthritis.

5. Trauma:

   • A direct blow or fall onto the shoulder, especially in younger individuals, can cause early degenerative changes that lead to arthritis in the AC joint.

Symptoms of AC Joint Arthritis

The symptoms of AC joint arthritis vary depending on the severity of the cartilage damage, but they commonly include:

1. Shoulder Pain:

   • Pain is typically located at the top of the shoulder, particularly near the AC joint. It is often worsened by overhead activities, lifting, or cross-body movements.

2. Stiffness:

   • As the arthritis progresses, stiffness in the shoulder joint becomes more noticeable, especially when trying to move the arm across the body or overhead.

3. Swelling:

   • Swelling around the AC joint may occur, especially after activity. This can result in discomfort and a reduced range of motion.

4. Grinding or Popping Sensation:

   • Some individuals may experience a grinding, clicking, or popping sensation when moving the shoulder, which occurs due to the friction between the bones as the cartilage wears away.

5. Weakness:

   • The shoulder may feel weak, particularly during activities that require lifting or rotating the arm.

Diagnosing AC Joint Arthritis

A healthcare provider will typically diagnose AC joint arthritis through the following:

1. Physical Examination:

   • The doctor will examine the shoulder, noting any tenderness over the AC joint, restricted range of motion, and pain with specific movements, such as cross-body adduction.

2. Imaging Tests:

   • X-rays: X-rays are essential in diagnosing AC joint arthritis, as they can reveal the narrowing of the joint space, bone spurs, or other signs of cartilage degeneration.

   • MRI: An MRI may be used in more complex cases to evaluate soft tissue damage and rule out other shoulder conditions that might be causing pain.

Treatment for AC Joint Arthritis

Treatment for AC joint arthritis typically focuses on managing pain and inflammation, improving shoulder function, and preventing further joint damage. Treatment options include both non-surgical and surgical approaches:

Non-Surgical Treatments

1. Rest and Activity Modification:

   • Avoid activities that worsen the pain, such as overhead lifting or pushing. Modify movements to protect the shoulder joint from further stress.

2. Ice and Heat Therapy:

   • Applying ice to the shoulder can help reduce inflammation and relieve pain, while heat may help relax muscles and improve blood flow.

3. Pain Relief:

   • Over-the-counter medications such as NSAIDs (Nonsteroidal Anti-Inflammatory Drugs) can help reduce pain and inflammation.

4. Corticosteroid Injections:

   • Corticosteroid injections directly into the AC joint can provide temporary relief from pain and inflammation.

5. Physical Therapy:

   • A physical therapy program can help strengthen the muscles around the shoulder, improve range of motion, and decrease the pain associated with movement. Exercises will focus on:

     • Restoring shoulder strength and flexibility

     • Improving joint stability

     • Reducing strain on the AC joint during functional movements

6. Acupuncture:

   • Some people find relief through acupuncture, which can help manage pain and reduce inflammation.

7. Orthotics or Shoulder Supports:

   • Wearing a shoulder brace or support can help reduce stress on the AC joint, especially during activities that aggravate the pain.

Surgical Treatments

If conservative treatments do not provide sufficient relief and the pain significantly interferes with daily activities, surgical intervention may be necessary. Surgical options include:

1. AC Joint Resection (Distal Clavicle Resection):

   • This is the most common surgical procedure for AC joint arthritis. It involves removing a small portion of the distal clavicle (the end of the collarbone) to create more space in the joint and reduce bone-on-bone friction.

2. Arthroscopic Surgery:

   • In some cases, arthroscopic surgery may be used to clean out the joint and remove any damaged cartilage or bone spurs. This minimally invasive approach can offer quicker recovery times compared to traditional surgery.

3. AC Joint Fusion:

   • In severe cases of AC joint arthritis, where other treatments have failed, an AC joint fusion may be necessary. This procedure involves fusing the clavicle to the acromion to eliminate motion in the joint and reduce pain.

4. Total Shoulder Replacement:

   • In very rare cases, when the entire shoulder joint is severely affected, a total shoulder replacement may be recommended, though this is usually reserved for individuals with advanced arthritis or combined shoulder joint issues.

Recovery and Prognosis

The recovery process for AC joint arthritis depends on the type of treatment received:

• Non-Surgical Treatments: With proper rest, physical therapy, and lifestyle adjustments, most individuals can manage the symptoms of AC joint arthritis and return to normal activities within weeks to months.

• Surgical Treatments: Recovery after surgery can take anywhere from 6 weeks to 6 months, depending on the procedure performed. Physical therapy will be an important part of the rehabilitation process to regain strength and mobility in the shoulder.

Prevention of AC Joint Arthritis

While you cannot entirely prevent AC joint arthritis, especially as you age, you can reduce your risk and slow the progression of the condition with the following strategies:

1. Strengthening Shoulder Muscles:

   • Regularly perform strengthening exercises for the shoulder muscles, including the rotator cuff, to support the AC joint and reduce wear on the cartilage.

2. Proper Technique and Posture:

   • Ensure proper posture and technique during sports and physical activities to avoid putting unnecessary stress on the AC joint.

3. Avoiding Overhead Strain:

   • Avoid repetitive overhead activities that strain the AC joint. When lifting, use proper technique to minimize stress on the shoulder.

4. Protecting Against Injury:

   • Wear protective gear when playing contact sports to prevent direct blows to the shoulder that may cause injury and lead to arthritis.

Australian Resources for AC Joint Arthritis

• Better Health Channel – Shoulder Arthritis
  https://www.betterhealth.vic.gov.au/health/conditionsandtreatments/shoulder-arthritis

• Healthdirect Australia – Shoulder Pain
  https://www.healthdirect.gov.au/shoulder-pain

• Arthritis Australia – Shoulder Arthritis
  https://arthritisaustralia.com.au/arthritis-information/arthritis-in-the-shoulder

Important disclaimer: This webpage contains general information only and is not intended to be relied upon as personal clinical advice. While we aim to keep information accurate and up to date, it may not reflect the most current research or your individual circumstances. Palms Physiotherapy & Allied Health does not accept liability for decisions made based on this information without an individualised assessment by an appropriately qualified health professional. If you have concerns, please contact us to book an assessment or speak with your GP/medical team.