AC joint narrowing refers to a reduction in the space between the bones that form the acromioclavicular (AC) joint, which is located at the top of the shoulder where the clavicle (collarbone) meets the acromion (part of the scapula or shoulder blade). This narrowing is often a sign of AC joint osteoarthritis or other degenerative changes.
Understanding the AC Joint
The AC joint allows for a range of arm movements and helps to transmit forces from the arm to the rest of the body. Like other joints, it is lined with cartilage that provides a smooth, low-friction surface for movement.
Causes of AC Joint Narrowing
- Osteoarthritis: The most common cause. Over time, the cartilage within the joint breaks down, leading to bone-on-bone contact and a reduced joint space.
- Trauma: Injuries such as AC joint separations or dislocations can damage the cartilage and accelerate the degenerative process.
- Repetitive Stress: Activities involving repetitive overhead motions (e.g., weightlifting, certain occupations) can contribute to the wear and tear of the joint.
Symptoms of AC Joint Narrowing
Symptoms can vary, but may include:
- Pain: Localized pain over the AC joint, which may worsen with activity or specific movements.
- Tenderness: Sensitivity to touch over the AC joint.
- Stiffness: Decreased range of motion in the shoulder.
- Clicking or popping: A sensation of clicking or popping within the joint during movement.
- Visible bump: In some cases, a visible bump may be present over the AC joint due to bone spurs or other changes.
Diagnosis of AC Joint Narrowing
Diagnosis typically involves:
- Physical examination: A doctor will assess your range of motion, palpate the AC joint for tenderness, and perform specific tests to evaluate the joint's stability.
- X-rays: X-rays can reveal narrowing of the joint space, bone spurs (osteophytes), and other signs of osteoarthritis.
- MRI (Magnetic Resonance Imaging): In some cases, an MRI may be used to further evaluate the soft tissues around the joint, such as the cartilage and ligaments.
Treatment of AC Joint Narrowing
Treatment options depend on the severity of symptoms and may include:
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Conservative Management:
- Rest: Avoiding activities that aggravate the pain.
- Ice: Applying ice packs to reduce inflammation.
- Pain medication: Over-the-counter pain relievers like ibuprofen or naproxen, or prescription pain medications in more severe cases.
- Physical therapy: Exercises to strengthen the muscles around the shoulder and improve range of motion.
- Corticosteroid injections: Injections of corticosteroids into the AC joint to reduce inflammation and pain.
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Surgical Management:
- Distal clavicle resection (Mumford procedure): Removal of a small portion of the end of the clavicle to create more space within the joint. This is typically considered when conservative treatments have failed to provide adequate relief.
- AC Joint Reconstruction: May be necessary in cases of significant instability or dislocations.
In summary, AC joint narrowing is a condition characterized by reduced space within the acromioclavicular joint, often due to osteoarthritis or other degenerative changes. Diagnosis involves physical examination and imaging, and treatment ranges from conservative measures to surgical intervention, depending on the severity of symptoms.
