This week we’re turning our focus to the Acromioclavicular (AC) Joint. The AC Joint is formed where the clavicle (collarbone) meets the acromion of the scapula (square part of shoulder blade). AC joint is stabilized by four ligaments between the two bones and when an injury occurs, the ligaments are stretched or torn resulting in what’s commonly known as a shoulder separation. 

AC joint injuries are more common in individuals younger than 35 and occur 5x more often in males. Younger athletes are more likely to sustain AC joint injuries due to participation in high-risk and collision activities and sports including football, biking, snow sports, hockey, and rugby. Shoulder separations are graded based on the amount of separation occurring at the joint. More mild cases usually do well with conservative care, but more severe cases often require surgical intervention followed by physical therapy.

Common Symptoms of AC Joint Pain include:

- General shoulder pain and swelling

- Pain and edema over the AC joint

- Decreased shoulder strength

- Visible bump above the shoulder (step-off deformity)

- Pain with lying on injured side

- Loss of shoulder range of motion

- Popping or clicking

- Increased pain and difficulty with reaching or lifting object overhead, reaching across body, and carrying heavy objects at your side

There are a few different classification scales to grade AC joint injuries. The Tossy Classification (1963) and Allman Classification (1967) have the injury classified in Grades 1-3. There is the more recent Rockwood Classification (1996) which is more precise and has Grades 1-6. In the Rockwood Classification, Grades 1-3 are much more common types of injuries and Grades 4-6 are usually the result of significant trauma and almost always require surgical intervention.

While AC joint injuries are usually the result of trauma, they can also occur due to overuse and gradual stress on the joint. The cartilage on the ends of the acromion and clavicle slowly loses its thickness due to the aging process and repetitive stress placed on the joint resulting in arthritis.  Overuse AC joint injuries are most common in those who perform heavy weightlifting or have jobs which require lots of overhead work.

The less severe AC joint injuries usually respond pretty well to conservative care and rest. The main focus initially is restoring pain free shoulder motion, initiating light shoulder strengthening, and pain management. As patients with AC joint injuries regain their motion, the focus turns more to regaining their strength and challenging the joint with overhead reaching, carrying, and lifting activities.

If you are interested in learning more or about treatment options, don’t hesitate to call/text 701-318-4731 or email connectptnd@gmail.com to learn how we can help. Don’t forget to follow on Facebook and Instagram to stay up to date on the happenings at Connect Physical Therapy.

- Alison Fuhrman, PT, DPT, CMPT, OCS