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Some joints in the body are more likely to develop problems due to normal wear and tear. The wear and tear can result in a condition called osteoarthritis; a type of arthritis caused by degeneration. Doctors sometimes refer to this type of arthritis as arthrosis.

Osteoarthritis of the Acromioclavicular (AC) Joint

The acromioclavicular (AC) joint in the shoulder is a common spot for osteoarthritis to develop in middle age. Degeneration of the AC joint can be painful and can cause difficulty using the shoulder for everyday activities.


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.

Osteoarthritis of the Acromioclavicular (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.

However, the AC joint is different from joints like the knee or ankle, because it doesn’t need to move very much. The AC joint only needs to be flexible enough for the shoulder to move freely. The AC joint just shifts a bit as the shoulder moves.


We use our shoulder constantly. The resulting strain makes AC joint osteoarthritis a common disorder.

AC joint arthrosis 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.


In its early stages, AC joint arthrosis 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.


Your doctor will want to get a detailed medical history, including questions about your condition and how it is affecting you. You will need to answer questions about past injuries to your shoulder. You may be asked to rate your pain on a scale of one to ten. Your doctor will also want to know how much your pain affects your daily tasks.

Diagnosis of AC joint osteoarthritis is usually made by physical examination. The AC joint is usually tender and painful when 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.

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.

Non-Surgical Treatment

Initial treatment for AC joint osteoarthritis usually consists of rest and anti-inflammatory medications such as aspirin or ibuprofen. Ice packs to the affected shoulder can also help relieve discomfort. 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 temporary, but may provide effective relief in the short term.

Cortisone may also produce serious side effects, so it must be used with great caution. When used in large doses or over long periods of time, cortisone can cause weight gain, thinning of the skin, cataracts and osteoporosis (brittle-bone disease).

Surgical Treatment

If conservative measures fail to relieve your pain, your doctor may recommend surgery. The most common procedure for AC joint osteoarthritis is resection arthroplasty. A resection arthroplasty involves removing the last half-inch 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. 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 from rubbing together.

Osteoarthritis of the Acromioclavicular (AC) Joint


If you don’t need surgery, a physical or occupational therapist may recommend range-of-motion exercises that should be started as pain eases, followed by a strengthening program. 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 doctor 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 may go 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 help avoid future problems.


Rheumatoid Arthritis of the Shoulder: Signs and Symptoms

Since rheumatoid arthritis of the shoulder is usually a symmetrical disease, both shoulders may be affected. The most common symptom of rheumatoid arthritis of the shoulder is a stiff or “frozen” shoulder. However, shoulder stiffness can also be a symptom of other causes including athletic injury, ankylosing spondylitis and tendinitis.

Osteoarthritis of the Acromioclavicular (AC) Joint

Other common symptoms of rheumatoid arthritis of the shoulder include:

  • Swelling and pain in one or more joints, lasting six weeks or more.
  • Fatigue and/or weakness
  • Shoulder stiffness following periods of immobility which gradually improves with movement
  • General sicknes, mild fevers, anemia and weight loss. Only a physician can make a diagnosis of Rheumatoid Arthritis

If you think you have any of these symptoms, please consult with your doctor.

Symptoms of Arthritis of the Shoulder

The symptoms of osteoarthritis of the shoulder are pain and reduced movement in the shoulder. The pain is typically aching in nature and can make it difficult to sleep. Certain movements may cause a grinding sensation or a catching sensation as the arthritic bone surfaces move against one another. Usually it is difficult to see any swelling in the shoulder joint because so much muscle covers it.

Treating Arthritis of the Shoulder

An artificial shoulder replacement is not the only treatment available for osteoarthritis of the shoulder. Once the diagnosis is made, your doctor may suggest several treatments to ease your pain and delay the artificial shoulder replacement. Like any arthritic condition, osteoarthritis of the shoulder may respond to anti-inflammatory medications such as aspirin or ibuprofen. The pain may also respond to acetaminophen (Tylenol® Arthritis Extended Relief).

Orthopedic surgeons are using some of the newer medications such as glucosamine and chondroitin sulfate more commonly today. These medications may be effective in helping reduce the pain in osteoarthritis of all joints.

Physical therapy may be suggested to regain as much of the motion in the joint and strength in the shoulder muscles as possible before undergoing a shoulder replacement. An injection of cortisone into the shoulder joint may give temporary relief. Cortisone is a powerful anti-inflammatory medication that can ease the inflammation and reduce the pain, possibly for several months. Most surgeons will limit the number of cortisone shots in any joint to two or three. If the shots fail to provide any lasting relief for several weeks to several months, your doctor may suggest surgery to replace the shoulder.

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