Shoulder injuries and different types of arthritis may cause acromioclavicular (AC) joint pain.

The AC joint in the shoulder connects the collarbone to part of the shoulder blade. One of the AC joint’s most important functions is supporting fluid arm movement. It helps coordinate movement in the upper parts of the body.

Shoulder injuries involving the AC joint may occur after a person falls during a contact sport, bike ride, or ski trip. Certain forms of arthritis can also damage the AC joint that worsens over time.

This article discusses the AC joint and possible causes of AC joint pain that will not go away. It also explores treatments for AC joint pain and when to contact a doctor.

A note about sex and gender

Sex and gender exist on spectrums. This article will use the terms “male,” “female,” or both to refer to sex assigned at birth. Click here to learn more.

Was this helpful?
Image of a person holding the front part of their shoulder while wearing workout clothesShare on Pinterest
MangoStar_Studio/Getty Images

Three bones make up the shoulder: the upper arm bone, shoulder blade, and collarbone. The AC joint connects the highest part of the shoulder blade to the collarbone.

The acromion process is a flat bony structure that projects off the shoulder blade. The AC joint connects the acromion process to the collarbone.

When the AC joint functions properly, it supports shoulder movements such as flexion and abduction. It also gives the shoulder blade its range of motion.

The AC joint is a synovial joint, one of three types of joints in the body. Synovial joints contain a cavity filled with synovial fluid. This fluid lubricates the joint and supports movement.

There are three types of ligaments that support the AC joint. Ligaments contain connective tissue and function to promote stability.

Some of the most common causes of AC joint pain include shoulder injuries and arthritis.


Injuries that involve the AC joint make up over 40% of all shoulder injuries. People typically experience these injuries during a sports accident. Sporting activities with a high rate of AC joint injuries include:

  • skiing
  • cycling
  • ice hockey
  • football
  • lacrosse

These injuries may also occur during a car accident or other traumatic events. A direct fall onto the shoulder is a typical cause of AC joint injuries. However, they may also occur after a person falls on their elbow or extended hand.

Shoulder injuries involving the AC joint are more common among males than females. Males in their 20s and 30s are more likely to experience these injuries.

Injuries to the AC joint may involve a sprain or tear of surrounding ligaments, depending on the severity of the injury.

Individuals experiencing shoulder pain after a fall should speak with a healthcare professional.


Shoulder arthritis may also cause AC joint pain. Osteoarthritis commonly affects the AC joint and the cartilage, a protective tissue that covers the exterior of bones.

When the cartilage wears down, the space between connected bones becomes smaller. The bones rub against one another, which can cause pain.

Rheumatoid arthritis is an autoimmune condition that causes inflammation within joints. This type of arthritis can also cause AC joint pain.

Treatment for AC joint injuries depends on the type of injury and its severity. A mild or moderate injury may respond to physical therapy, corticosteroid injections, and oral pain medications.

In some cases, doctors may recommend surgery for treating AC joint pain. Distal clavicle excision (DCE) is one of the most common procedures for osteoarthritis of the AC joint.

During DCE, a surgeon removes the outer end of the collarbone. This procedure may help reduce AC joint pain and improve the range of motion in the affected shoulder.

People experiencing shoulder arthritis may benefit from weight loss or moderate exercise. Other options for treating arthritis of the shoulder may include:

Anyone experiencing AC joint pain that will not go away should consult a healthcare professional. They can examine a person’s symptoms and recommend the best course of treatment.

Anyone experiencing ongoing or severe shoulder pain should visit a doctor. Individuals at risk of arthritis should also speak with a healthcare professional. Some of the people at high risk of arthritis include:

  • older individuals
  • those with a family history of arthritis
  • people who smoke
  • individuals who have experienced joint injuries in the past
  • those with more weight or obesity

Chronic shoulder pain may be a sign of AC joint injury or arthritis. People who experience ongoing shoulder pain or are concerned about their shoulder pain should speak with a healthcare professional.

The AC joint connects the upper part of the shoulder blade to the collarbone. A healthy AC joint supports arm movements and range of motion in a person’s shoulder.

Shoulder injuries or different types of arthritis may lead to AC joint pain that will not go away. These may include sports injuries, rheumatoid arthritis, or osteoarthritis.

Anyone experiencing shoulder pain that does not resolve or worsens over time should consult a healthcare professional for further assessment.