Shoulder Separation and AC Joint Pain | Mathew Mazoch, MD

Bone & Joint Clinic of Baton Rouge | Sports Medicine

  Contact : (225) 766-0050

Shoulder Separation and AC Joint Pain

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Introduction to AC (Acromioclavicular) Joint Pain and Shoulder Separation

Some joints in the body are more likely to develop problems than others, one of these joints is the acromioclavicular joints (AC joint).  Falls on the point of the shoulder often cause injury to the AC joint (often called a shoulder separation).  Wear and tear degeneration causes the cartilage that cushions the joint to wear out. This type of arthritis is called osteoarthritis.  The acromioclavicular (AC) joint in the shoulder is a common spot for osteoarthritis to develop. Injury or degeneration of the AC joint can be painful and can cause difficulty using the shoulder for everyday activities.


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This diagram shows the ligaments that are commonly injured in a separated shoulder.



Anatomy of the AC joint and Shoulder Separation

What exactly is the AC joint?

The shoulder is made up of three bones: the scapula (shoulder blade), the humerus (upper arm bone), and the clavicle (collarbone).  The part of the scapula that makes up the roof of the shoulder and connects with the clavicle is called the acromion. The joint where the acromion and the clavicle join is the AC joint.  Injury or degeneration of this joint can often cause pain and limited activity.

Causes of AC Joint Pain and Shoulder Separation

Why does degeneration of the AC joint occur?

We use our shoulder constantly. The resulting strain makes AC joint osteoarthritis a common disorder. The AC joint is under constant stress as the arm is used overhead. Weightlifters and others who repeatedly lift heavy amounts of weight overhead tend to have an increased incidence of the condition, and often at a younger age.

AC joint osteoarthritis may also develop following an injury to the joint, such as an AC joint separation. This injury is fairly common. A separation usually results from falling on the shoulder. The shoulder does heal, but many years later degeneration causes the AC joint to become painful.

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Hard falls on the point of the shoulder can often cause AC joint separations.

Symptoms of AC joint pain and Shoulder Separation

What are the symptoms of this condition?

In its early stages, AC joint osteoarthritis usually causes pain and tenderness in the front of the shoulder around the joint. The pain is often worse when the arm is brought across the chest, since this motion compresses the joint. The pain is vague and may spread to include the shoulder, the front of the chest, and the neck. If the joint has been injured in the past, there may be a bigger bump over the joint on the affected shoulder than on the unaffected shoulder. The joint may also click or snap as it moves.  Acute injuries often result in an inability to lift the arm over the head or a loss of strength.

Diagnosis of AC Joint Pain and Shoulder Separation

Diagnosis of AC joint osteoarthritis is usually made by physical examination. The AC joint is usually tender. A key finding is pain as the joint is compressed. To test for this, your arm is pulled gently across your chest. Your doctor may inject a local anesthetic such as lidocaine into the joint. If the AC joint is the problem, the injection will temporarily reduce the pain.  After an acute injury there is often a lot of swelling directly over the joint and the involved shoulder may seem to hang lower that the other side.  It is often painful initially to have the arm unsupported.  Sometimes pain near the AC joint can be caused by other conditions such as impingement, bursitis, tendinitis, biceps, and rotator cuff problems.

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The image shows the swelling and deformity around the right AC joint after an injury. Notice the side to side difference.

Your doctor may want to take X-rays of the AC joint. X-rays can show narrowing of the joint and bone spurs around the joint, which are signs of degeneration.  It can also show displacement in the setting of an acute injury.  A comparison view of the other side is often helpful to determine the relative degree of displacement in an acute setting.

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This is an image of an x-ray of an arthritic right shoulder AC joint

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This picture shows an AC joint separation of the right shoulder on an x-ray.


Nonsurgical Treatment of AC joint pain and arthritis

Initial treatment for AC joint osteoarthritis usually consists of rest and anti-inflammatory medications such as aspirin or ibuprofen. A rehabilitation program may be directed by a physical or occupational therapist. If the pain doesn’t go away, an injection of cortisone into the joint may help. Cortisone is a strong medication that decreases inflammation and reduces pain. Cortisone’s effects are often temporary, but it can give very effective relief in the short term.

Nonsurgical Treatment of Shoulder Separation

Shoulder separations come in different severities.  Depending on the type of injury sustained and the amount of displacement of the AC joint determines treatment.  Lower grade AC joint separations are generally treated non-surgically with rest, ice, anti-inflammatories, and a short period of sling immobilization.


Surgical options for AC Joint pain and Arthritis

If nonsurgical measures fail to relieve your arthritic pain, your doctor may recommend surgery.

The most common procedure for AC joint osteoarthritis is resection arthroplasty. A resection arthroplasty involves removing a small portion of the end of the clavicle. This leaves a space between the acromion (the piece of the scapula that meets your shoulder) and the cut end of the clavicle, where the joint used to be. Your surgeon will take care not to remove too much of the end of the clavicle to prevent any damage to the ligaments holding the joint together. Usually only a small portion is removed, less than one cm (about three-eighths of an inch). As your body heals, the joint is replaced by scar tissue. Remember, the AC joint doesn’t move much, but it does need to be flexible. The scar tissue allows movement but stops the bone ends from rubbing together.

This procedure can be done in two ways. Today, it is more common to do this procedure using the arthroscope. An arthroscope is a slender tool with a tiny TV camera on the end. It lets the surgeon work in the joint through a very small incision. This may result in less damage to the normal tissues surrounding the joint, leading to faster healing and recovery.

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This shows an arthroscopic view of the resection of an arthritic AC joint.

The older open method of performing this operation is done by making a small incision over the AC joint. The AC joint is very close to the surface of the skin and can be easily reached through a small incision. The surgeon can then use a special saw or other instrument to shave off a small portion of the end of the clavicle.

Surgical Management of Shoulder Separation

In more severe cases of AC joint injury surgical management is considered.  Depending on the structures injured and the patients anatomy and demands, different procedures can be used to help stabilize this joint.  Timing between injury and procedure can also effect reconstruction options.

Rehabilitation for AC Joint Pain and Shoulder Separation

Nonsurgical Rehabilitation

If you don’t need surgery, range-of-motion exercises should be started as pain eases, followed by a program of strengthening. At first, exercises are done with the arm kept below shoulder level. The program advances to include strength exercises for the rotator cuff and shoulder blade muscles. The goal is to get your shoulder moving smoothly and to learn how to control your symptoms. You will probably progress to a home program within four to six weeks.

After Surgery

Your surgeon may have you wear a sling to support and protect the shoulder for a few days. A physical or occupational therapist will probably direct your recovery program. The first few therapy treatments will focus on controlling the pain and swelling from surgery. Ice and electrical stimulation treatments may help. Your therapist may also use massage and other types of hands-on treatments to ease muscle spasm and pain.

Therapy can progress safely and quickly after a simple arthroscopic resection. Treatments start out with range-of-motion exercises and gradually work into active stretching and strengthening. You need to avoid doing too much, too quickly.

Therapy goes slower after surgeries where an incision is made through the shoulder muscles. Therapists usually wait up to two weeks before starting range-of-motion exercises. You will begin with passive exercises. In passive exercises, the shoulder joint is moved, but your muscles stay relaxed. Your therapist gently moves your joint and gradually stretches your arm. You may be taught how to do passive exercises at home.

Active therapy starts after four to six weeks. Active range-of-motion exercises help you regain shoulder movement using your own muscle power. You might begin with light isometric strengthening exercises. These exercises work the muscles without straining the healing joint.

At about six weeks, you will start more active strengthening. Exercises will focus on improving strength and control of the rotator cuff muscles and the muscles around the shoulder blade. Your therapist will help you retrain these muscles to keep the ball of the humerus centered in the socket. This helps your shoulder move smoothly during all your activities.

Some of the exercises you’ll do are designed to get your shoulder working in ways that are similar to your work tasks and sport activities. Your therapist will help you find ways to do your tasks that don’t put too much stress on your shoulder. Before your therapy sessions end, your therapist will teach you a number of ways to avoid future problems.

Therapy after shoulder separation surgery depends on the type of procedure done and the patient characteristics.

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Final thoughts on AC joint pain and Shoulder Separation

AC joint pain and shoulder separations can cause significant pain and decreased quality of life.   Appropriate treatment can result in significant pain relief and an increased quality of life.  If you have any further questions please don’t hesitate to schedule an appointment with Dr. Mazoch.