What Is AC Joint Arthritis? – Healthline

Your acromioclavicular (AC) joint is the part of your shoulder where your collarbone and shoulder blade meet. It contributes your shoulder’s mobility, such as raising your arm overhead.

Arthritis in the AC joint is a most common cause of shoulder pain in adults. Arthritis here usually develops when the smooth cartilage between your scapula and collar bone wears down, becoming thin and rough. This can cause pain and inflammation in the joint when the end of your bones rub against each other.

In this article, we examine the role of your AC joint in healthy shoulder movement and how AC joint arthritis is treated.

Your shoulder is a ball-and-socket joint that provides you with a large range of motion. The trade-off for this large range is that your shoulder is prone to injury. As many as 67 percent of people will experience shoulder pain in their life and up to 26 percent experience it at any given time.

Your shoulder joint consists of three bones:

• humerus (upper arm bone). The head of your humerus makes up the ball of your shoulder joint.
• scapula (shoulder blade). Your scapula makes up the socket of your shoulder joint, and many muscles and ligaments help support and stabilize your joint capsule.
• clavicle (collarbone). The end of your clavicle connects to a part of your scapula called the acromion. They’re connected with a thick ligament called the acromioclavicular ligament. This area is your AC joint.

The delicate structures of your AC joint make it particularly prone to getting hurt. Injuries to this area make up more than 40 percent of shoulder injuries.

A healthy AC joint only allows limited motion. During certain motions like raising your arm over your head, your acromion meets the end your clavicle. If the joint becomes inflamed or painful, it can restrict your range of motion when you move your arm.

AC joint pain is usually caused by traumatic injuries or arthritis. Arthritis is a group of conditions that cause inflammation and degeneration of a joint. The most common form of arthritis is called osteoarthritis. It’s caused by a wearing down of a joint due to repetitive use, making age the biggest risk factor.

Sudden trauma to the AC joint can lead to post-traumatic arthritis that tends to develop soon after the injury. Most of the time it’s temporary and …….

Source: https://www.healthline.com/health/ac-joint-arthritis