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[Patient Adviser]

What to Do About AC Joint Injuries

Robert J. Johnson, MD

Practice Essentials Series Editors:
Kim Harmon, MD; Aaron Rubin, MD


The muscles, joints, and bones of the shoulders form a base of support that allows your arms to swing, lift, or throw (figure 1). One of these bones, the collarbone, is also called the clavicle. Above your arm is an extension of the shoulder blade called the acromion. Where these two bones meet at the top of the shoulder is the acromioclavicular (AC) joint. The AC joint is not the shoulder joint. The shoulder joint is where the bone of the upper arm (humerus) meets a shallow socket that is also part of the shoulder blade.

[Figure 1]

Q. What is a 'separated shoulder'?

A. A separated shoulder is a dislocation of the AC joint that can be caused by a direct or indirect blow to the shoulder. The ligaments that keep the clavicle in proper position become stretched or torn.

There are six different types of AC joint separations. The most common types can be treated by your doctor without a cast or surgery. Because some shoulder separations may need surgery, you should see your doctor for diagnosis and treatment. If surgery is not necessary, most separated shoulders can be treated with an arm sling followed by special rehabilitation exercises, such as those described on the next page.

Q. Does an AC joint separation show on x-rays?

A. X-rays are necessary to show if the clavicle is broken. They can also help distinguish which of the six types of AC joint separation may have occurred.

Q. What other injuries can happen to the AC joint?

A. The end of the clavicle can break. The broken bones may need surgery because the ligaments can't hold the broken parts of the bone in proper position. Your doctor will carefully examine the injury to decide whether surgery is necessary.

Q. Is arthritis a concern?

A. Arthritis can affect the AC joint just like any other joints. A separated shoulder or a broken clavicle may increase your future risk of developing arthritis of the AC joint. Weight lifters and people who do upper-body workouts or play sports that involve shoulder strength or throwing may also be more likely to develop AC joint arthritis. Arthritis can also develop with normal aging.

Q. What can I do to minimize joint damage?

A. Once symptoms develop, discontinue any pain-provoking exercises. Weight lifters should avoid "locking out" the bench press, use a narrower grip on the bar, and avoid bending the elbows below horizontal. Follow your doctor's instructions for care after injury, and be sure to do the recommended exercises to regain strength and range of motion. Your doctor or physical therapist will show you how to do the exercises and tell you how often to do them.

Q. Which exercises help?

A. Unless your doctor tells you otherwise, perform the following exercises two or three times a week. Do 12 to 18 repetitions per set, and do three sets of each. Begin by using 1- or 2-pound hand weights, and gradually increase the weight to 8 pounds as you are able. Consult your doctor if you experience more than mild discomfort when doing any of these exercises.

The first three exercises (figures 2 through 4) increase strength and flexibility. In addition, two exercises help stabilize the scapula. The "push-up plus" (not illustrated) is just like a regular, full-length push-up except that as you come up, you emphasize pushing your back toward the ceiling as high as possible. (Bent-knee pushups do not work as well for this exercise.) The seated press-up (figure 5) is another scapular stabilizer.

[Figure 2]

[Figure 3]

[Figure 4]

[Figure 5]

Remember: This information is not intended as a substitute for medical treatment. Before starting an exercise program, consult a physician.