What is AC joint arthritis?
The acromioclavicular (AC) joint is the place in the shoulder where the clavicle (collarbone) connects to the tip of the scapula (shoulder blade) known as the acromion. Like most joints in the body where bones meet, there is cartilage between the bones, which is the white tissue that allows them to move smoothly against each other. Although many people are not familiar with the AC joint, arthritis in this area is actually more common than arthritis in the glenohumeral joint (the shoulder’s large ball-and-socket joint). AC joint arthritis comes in many forms, most commonly osteoarthritis, and is typically indicated by a gradual onset of pain, tenderness and limited range of motion.
What causes AC joint arthritis?
Research suggests most people develop AC joint arthritis as they age. Additionally, most people who develop the condition have one or more risk factors:
- Osteoarthritis – happens from gradual wear and tear. Over time, the outer cartilage of the joint is worn away, which causes the bones to scrape together during movement
- Joint trauma or injury – can include previous fractures, AC joint separations, or surgery. This can cause damage that eventually leads to cartilage damage and arthritis over time
- Chronic overuse – those who participate in repetitive shoulder movements or overhead lifting can cause general inflammation that may lead to joint damage in the future
- Rheumatoid arthritis – the immune system attacks the lining of the joint
What are the symptoms?
The signs and symptoms of acromioclavicular arthritis (AC joint arthritis) tend to progress gradually. In most but not all cases, the symptoms of AC joint osteoarthritis come and go, becoming worse and more frequent over months or years. Other symptoms include:
- Pain with certain motions
- Joint tenderness and pain
- Radiating pain
- Trouble sleeping
- Stiffness and swelling
- Clicking or popping sensation when stress is put on the joint
How is AC joint arthritis treated?
Initial treatment consists of conservative measures, such as rest, activity modification, anti-inflammatory medications, physical therapy, and corticosteroid injections. These might help to control the pain and symptoms associated with AC joint arthritis.
When nonsurgical treatments fail to relieve persistent pain, shoulder surgery may be an option. Since the pain is due to the ends of the bones rubbing against each other, surgical treatment involves removing of a portion of the end of the clavicle – called a distal clavicle excision (DCE). Dr. Potts performs this procedure using minimally invasive shoulder arthroscopy. Arthroscopic DCE is associated with better pain relief at 3 months, lower infection risk, and faster return to activity.
People with severe AC joint arthritis almost always have other coexisting shoulder pathology as well, including rotator cuff tears or labral tears. These problems can also be identified and addressed during the arthroscopic procedure. The best possible pain relief may come from a combination of two or more treatment options.