Acromioclavicular (AC) Joint Arthritis

The shoulder is one of the most complex joints in your body and allows your arm to rotate and move in many different directions. The shoulder joint is described as a “ball and socket” joint, however, the socket is very shallow and is similar to a golf ball resting on a tee. The shoulder is made up of three bones: the humerus (upper arm bone), the clavicle (collarbone), and the scapula (shoulder blade). The outer portion of the scapula bone is called the glenoid and is the golf tee where the ball of the humeral bone rests to make up the shoulder joint. The shoulder joint is also called the glenohumeral joint and you may see it referred as this in test results.

Two smaller joints complete the “shoulder girdle” and are the acromioclavicular joint (AC) and the sternoclavicular (SC) joints. The AC joint is the connection between the acromion (a bony protrusion from the shoulder blade) and the clavicle (collarbone). The SC joint is the connection between the sternum of your chest and the clavicle.

AC joint arthritis can occur in patients with previous AC joint injury or those who perform repetitive overhead activities.

Symptoms & Diagnosis

Patients with AC joint arthritis typically have pain with overhead movement of the arm or when reaching across the body.

AC joint arthritis is diagnosed using physical examination and imaging studies to confirm the diagnosis. The physical examination is used to identify areas of pain, weakness, and changes in range of motion of the shoulder. Specific tests are able to identify if the shoulder pain is due to AC joint arthritis. X-rays of both shoulders help evaluate the space between the bones of the AC joint and evaluate for signs of arthritis.

Treatment

Treatment of AC joint arthritis can be done with non-surgical or surgical means. The goal of treatment is to reduce pain and regain function of the shoulder. Non-surgical treatment is used for the majority of patients with AC joint arthritis. These therapies are used to reduce inflammation associated with injury and allow you to strengthen the shoulder, decrease inflammation, and regain function. Non-surgical treatment options include:

• Rest

• Change in activities: Avoiding activities that irritate the shoulder, specifically overhead motions

• Non-steroidal anti-inflammatory medications (NSAIDs) can help decrease inflammation

• Injections: Steroid injections can help decrease inflammation in the AC joint. Steroid injections can be used if rest, activity modification, and NSAIDs do not improve the symptoms.

• Physical therapy: This is an important tool to help you strengthen and retrain the muscles of the rotator cuff to work better together

Surgery is used to treat patients who continue to have symptoms after trying non-surgical treatment.

• Arthroscopic AC joint resection is performed with small incisions around the shoulder and a camera and specialized instruments. A small portion of the acromion and end of the collarbone are removed so that the bones do not rub against each other and cause pain.