If you feel pain in your shoulder, the cause may be your acromioclavicular or AC joint. According to a 2021 study published in the Archives of Physiotherapy, 67% of adults experience similar pain. Over time, the smooth cartilage that protects this critical joint can wear down, causing friction between the intersecting bones.
Damage to your AC joint will affect your ability to move your arm, but the proper treatment can help.
What Is the AC Joint?
The shoulder is one of the most flexible joints in your body, but it comes at a cost. The ball and socket design of the joint allows a pitcher to pitch a fastball, a quarterback to throw a perfect spiral, and you to take the groceries out of your car. Unfortunately, the fact that you can move your arm in many directions makes that joint prone to injury.
This joint intersects three bones:
- Humerus – The upper arm bone
- The scapula – The shoulder blade
- The clavicle – The collarbone
At the top of the humerus bone is a large ball that fits into a socket found on the scapula. The collarbone intersects with the scapula just above the socket. Ligaments hold the bones together and allow them to function as the unit that is your joint.
It is at that place where the collarbone and the scapula meet that you find the acromioclavicular joint. Each bone has smooth cartilage at the point where it meets another bone. This tissue protects that bone from friction as you move your arm.
What Causes AC Pain?
The acromioclavicular joint pain in your shoulder can come from a traumatic injury like a fall or an accident, but AC pain is often a repetitive use injury. For example, imagine something running over a garden hose lying across the lawn repeatedly. It will eventually wear down the protective coating on the hose causing damage to the rubber or plastic material.
Certain repetitive movements can have a similar effect. As you lift your arms over your head, you stress the cartilage that protects the AC joint and wears it down. The pain is the friction caused by the bones rubbing together.
What Are the Risk Factors for AC Pain?
The most prevalent risk factor is lifting your arm over your head repeatedly. That is why AC injuries are common for weightlifters. As they push the weights over their head, they cause stress on the AC joint and eventually damage the cartilage.
Some other risk factors for AC pain include:
- Age: Even if you are not a weightlifter, you may experience pain as you get older.
- Traumatic injury: This can make the shoulder joint unstable and put stress on the AC.
- Manual work: Any work that requires you to raise your arms, like lifting boxes, can lead to problems.
- Inflammatory arthritis: Conditions like rheumatoid arthritis can wear down joints.
- Infection: An infection in the joint capsule can cause damage.
Not all shoulder pain comes from the AC joint, though. There are specific symptoms that might indicate this joint is the problem.
What Are the Symptoms of AC Pain?
The shoulder joint is complex, so a lot can go wrong. Some common symptoms that might indicate AC joint damage include:
- Pain at the top of your shoulder that may radiate into the neck or down the arm
- Restricted motion in the shoulder
- A snapping or clicking sound as you move your arm
Any of these symptoms may mean you need treatment for AC damage.
What Are Some Treatments for AC Pain?
Your healthcare provider will likely recommend a multidisciplinary approach to treatment that might include the following:
- Medication
- Physical therapy
- Changes in exercise
- Corticosteroid injections
Laser therapy is another approach that might help ease the pain.
How Laser Therapy Can Help AC Pain
Laser therapy uses light to stimulate healing that can decrease pain and inflammation. If your pain is new, it can help you avoid injuring the joint further, especially when combined with other treatments like rest and physical therapy.
Overuse injuries like those seen with the AC joint can start with tendonitis or inflammation of the connective tissue around the joint. Although tendonitis is different from arthritis, it can cause similar pain. It may also be a warning sign that you need to rest the joint and allow healing.
Laser therapy is a non-surgical and pain-free way to treat injuries like AC joint pain. Six to twelve sessions over a few weeks can stimulate healing, making the joint feel better. Then, lifestyle changes may help you prevent further damage.
Find out more about laser therapy for AC joint pain today by contacting an Aspen Laser professional in your area.
This article was originally published on Sept 16, 2019, and was last updated on January 5, 2023.
