Arthritis

What is arthritis?
 

Arthritis is the loss or damage of joint (articular) cartilage (def.). Cartilage is a smooth, shiny surface that covers the ends of your bones. Normally, when cartilage rubs together, you have smooth and painless motion. When your cartilage degenerates, however, you can suffer from pain and limitation of motion.When you have arthritis, your soft tissues — the muscles, tendons, and ligaments surrounding and supporting the joint — can also become weak and unable to function.

About one in every 3 Americans suffers from some form of arthritis — the number one cause of disability in the U.S., according to the Centers for Disease Control and Prevention.

 

Video animation View an animation of arthritis.

What causes arthritis? Who's at risk?
 

Arthritis can be caused by several factors, depending on the form it takes and what area within the shoulder is affected. Three main types of arthritis generally affect the shoulder:

The shoulder joints most commonly affected are:

  • The glenohumeral (ball and socket) joint
  • The acromioclavicular joint (where the shoulder blade and collarbone meet)

To provide you with effective treatment, your physician will determine what type of arthritis you have, and which joint is affected.

Osteoarthritis of the shoulder
 

Sometimes the rubbery outer layer of the articular cartilage that covers the ends of your bones deteriorates. The result is called osteoarthritis. Osteoarthritis affects the entire joint — causing cartilage loss, bone damage, formation of bone spurs (def.), and soft tissue inflammation. Your cartilage loses its ability to absorb shocks and repair itself.

Since osteoarthritis results from wear-and-tear, it most often is seen in older people. In fact, half of the U.S. population aged 65 or older is likely to show evidence of osteoarthritis in at least one joint. There also is increasing evidence that genetics may play some role in this disease. In addition, osteoarthritis may be caused by certain diseases such as Paget's disease (def.), by injury, or by sports- or work-related overuse of the shoulder.

Rheumatoid arthritis of the shoulder (inflammatory arthritis)
 

There are several types of inflammatory arthritis; the most common include rheumatoid arthritis and psoriatic arthritis. These chronic (ongoing) diseases occur as the result of inflammation of the lining (synovium (def.)) of your joints. This inflammation is called synovitis.

Rheumatoid arthritis is a progressive disease:

  • The first stage is the swelling and inflammation of the synovial lining
  • The second stage is rapid cell division and growth that causes the synovium to thicken
  • The third stage happens when the inflamed cells release enzymes that may damage bone and cartilage

Approximately 2.1 million people in the US have rheumatoid arthritis. Anyone can be affected by the disease, including children (juvenile rheumatoid arthritis), but 70 percent of those affected are women. Symptoms usually begin between 30 and 50 years of age.

It's not known exactly what causes rheumatoid arthritis. It may in fact be a combination of several similar diseases rather than a single disease. It is known, however, that the immune system is a key player in the disease process. If you have rheumatoid arthritis, your immune system is mistaking your healthy joint tissue for a foreign invader and attacking it.

Posttraumatic arthritis of the shoulder
 

This type of arthritis can occur at any age and can be caused by an accident (trauma) or by shoulder surgery that was performed as a treatment for dislocation (instability). The arthritis may occur relatively soon — or years after the original injury.

Other types of arthritis of the shoulder
 

There also are other, less common, forms of arthritis that can affect the shoulder. Septic arthritis can result from infection from bacteria, viruses or other microorganisms. It also is associated with rheumatoid arthritis. Avascular necrosis (osteonecrosis) develops when the blood supply to the bone is disrupted and the bone begins to die. Both forms of arthritis can result from injury, fracture, or other nontraumatic causes.

What are the symptoms of arthritis? How is it diagnosed and treated?
 

Glenohumeral joint arthritis
Glenohumeral joint arthritis occurs in the glenohumeral (ball and socket) joint. The most common symptoms are pain and restriction of motion.

To diagnose the condition, your physician will take your medical history and examine your shoulder to assess your range of motion. X-rays may be helpful to show bone spurs and loss of joint space — an indication of damaged cartilage. An MRI (def.) also may be ordered to look for joint capsule (def.) swelling and bone spurs.

Your physician may suggest NSAIDs (def.) to treat the pain and inflammation. It also may be necessary to modify some of the activities that affect your shoulder movement. Your physician also may suggest a corticosteroid injection (def.) into the joint to decrease painful symptoms.

Early stages of glenohumeral joint arthritis can often be managed without surgery. However, if arthritis is severe or symptoms are not well controlled with rest, medication and injections, a shoulder replacement may be recommended.

Acromioclavicular joint arthritis

Acromioclavicular joint arthritis occurs where the collarbone (clavicle) meets the shoulder blade (scapula) at the acromion (def.). The most common symptoms are pain at the top of the shoulder, pain when crossing your arm in front of the body (such as reaching to touch the other shoulder) or pain when raising your arms above your head.

Arthritis in this joint most commonly results from:

  • Osteoarthritis (degenerative arthritis)
  • Repetitive overhead activities (weight lifting, overhead labor)
  • Previous injury (shoulder separation)

To diagnose the condition, your physician will take a medical history and examine your shoulder for tenderness. X-rays may be helpful in showing bone spurs and loss of joint space — an indication of damaged cartilage. An MRI also may be ordered to look for joint capsule swelling and bone spurs pushing down into the rotator cuff.

Your physician may suggest NSAIDs and ice packs to treat the pain and inflammation. It also may be necessary to modify some of the activities that affect your shoulder movement. Your physician may suggest a corticosteroid injection into the joint to decrease painful symptoms. In addition,physical therapy may be useful.

If arthritis is severe or symptoms are not well controlled with rest, medication, and injections, surgery may be recommended to remove the end of the collarbone.

 
What can I expect long-term?
 

The different types of arthritis affect everyone differently. In some people, their arthritis progresses rapidly, with severe symptoms. This requires aggressive management of the disease.

Fortunately, the development of new medications and innovations in joint preserving or joint replacement procedures are continuing.