According to the Arthritis Foundation, there are over a hundred different rheumatic diseases that cause pain and swelling in the joints and connective tissue. We often use the word "arthritis" to refer to such diseases. All told, an estimated 40 million Americans are affected with some form of arthritis or rheumatic disease. The latest study from the Centers for Disease Control and Prevention (CDC) places the numbers even higher with an estimated 70 million people, or almost one in three in the United States, reporting arthritis or chronic joint symptoms. Follow the links below to learn about some of the most common forms.

Osteoarthritis is the most common type of arthritis. According to the National Institutes of Health, the disease is responsible for more trouble walking and stair climbing than any other disease, and it is the most common indication for total joint replacement of the hip and knee.

In osteoarthritis, the cartilage that normally covers our bones starts to degenerate. As a result, bones start to rub up against each other, causing pain and loss of movement. The National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS) says this type of arthritis is sometimes called degenerative arthritis or degenerative joint disease, and the risk of developing this form of arthritis may be increased if someone experiences joint injuries either from sports, accidents or repetitive movements. .

All told, osteoarthritis affects over twenty million Americans. Most are over the age of 45, and women are more often affected than men, according to the Arthritis Foundation.

Gout is a form of arthritis that most often attacks small joints such as the big toe in sudden severe episodes. NIAMS says it accounts for about five percent of all cases of arthritis and results from deposits of crystals of uric acid in joints and/or connective tissue. If the body increases its production of uric acid or if the kidneys do not eliminate enough uric acid from the body, levels build up (a condition called hyperuricemia). Hyperuricemia may also result when a person eats too many high purine foods. The most commonly implicated foods are shellfish, red meats and alcohol. Other foods that may cause problems include:

• liver and other organ meats
• dried beans and peas
• anchovies
• gravies

According to the National Institutes of Health, men are more likely to develop gout than women, and men aged 40 to 50 are most commonly affected. Women rarely develop gout before menopause.

NIAMS says scleroderma (or schleroderma) is both a rheumatic disease that can cause inflammation and pain in the muscles and joints, as well as a connective tissue disease that can cause thickening, hardening or tightening of the skin, blood vessels and internal organs. The Scleroderma Foundation says scleroderma affects over 300,000 people in the U.S., and that women are four times more likely to develop it than men.

Scleroderma is a chronic disease, which occurs because the body produces too much of a protein called collagen. Excess collagen is deposited causing thickening and hardening. There are two types of scleroderma:

• In localized scleroderma, the skin develops either hard, oval patches or lines or streaks. According to the Scleroderma Foundation, this type is more common in children.
• In generalized or systemic scleroderma, also called systemic sclerosis, the thickening and hardening affect connective tissue throughout the body, including the skin, the esophagus, gastrointestinal tract, lungs, kidneys, heart and other internal organs. It may also affect blood vessels, muscles and joints.

Scleroderma can also produce abnormal sensitivity to cold, as well as oral and dental problems, fatigue, and/or weight loss. NIAMS says one of the most common problems associated with scleroderma, is Raynaud's phenomenon creating the potential for painful skin ulcers which can be made worse by smoking. In addition, some people with systemic sclerosis develop severe lung disease, including pulmonary fibrosis (hardening or scarring of lung tissue because of excess collagen) and pulmonary hypertension (high blood pressure in the artery that carries blood from the heart to the lungs). Others may develop heart problems; including scarring and weakening of the heart and abnormal heart beat . Kidney problems can also occur.It's essential that people with scleroderma discuss potential problems with their doctor. Treatment and management focus on relieving symptoms and limiting damage.

Lupus is a chronic rheumatic disease in which inflammation affects joints, muscles and other parts of the body, including the heart, lungs, skin, joints, kidneys, blood and nervous system. The most common and serious type of lupus is called systemic lupus erythematosus (SLE). NIAMS says a combination of genetic, environmental, and possibly hormonal factors may work together to cause the disease. Studies suggest that the risk of developing lupus is higher if someone in your family has it.

In lupus, the immune system produces antibodies against the body's own healthy cells and tissues. These antibodies, called autoantibodies ("auto" means self), contribute to the inflammation of various parts of the body, causing swelling, redness, heat, and pain. In addition, some autoantibodies join with substances from the body's own cells or tissues to form molecules called immune complexes. A buildup of these immune complexes in the body also contributes to inflammation and tissue injury in people with lupus. Symptoms of lupus can include:

• inflammation
• facial sores and/or a butterfly-shaped rash over the cheeks and nose (malar rash)
• ulcers of the mouth
• sensitivity to sunlight
• pain and joint stiffness
• kidney disorders
• blood problems such as anemia
• immune problems
• shortness of breath
• neurologic problems, such as psychosis or seizures

According to the Arthritis Foundation, lupus affects women more than men. It can occur in young children, as well as older people, and it occurs more often in African Americans.

Although we usually associate arthritis with aging, anyone can develop the disease, including children. Juvenile arthritis is a general term for any of the dozens of different types of arthritis when they occur in children.

NIAMS says the most common type of arthritis that affects children is juvenile rheumatoid arthritis. JRA is an autoimmune disorder, which means that the body mistakenly identifies some of its own cells and tissues as foreign. The immune system which normally helps to fight off harmful, foreign substances such as bacteria or viruses, begins to attack healthy cells and tissues. The result is inflammation, marked by:

• Redness
• Heat
• Pain
• Swelling

The main difference between juvenile and adult rheumatoid arthritis is that many people with JRA outgrow the illness, while adults usually have lifelong symptoms. Studies estimate that by adulthood, JRA symptoms disappear in more than half of all affected children. Additionally, unlike rheumatoid arthritis in an adult, JRA may affect bone development as well as the child's growth.

Ankylosing Spondylitis (AK) is a chronic disease that primarily affects the spine and back. In AK, the joints and ligaments that normally help us move our backs become inflamed and may even fuse together, resulting in a permanently stooped posture. The Arthritis Foundation says this primarily affects men between the ages of 16 and 35. Although the cause is unknown, genetics may increase the risk of having AK. The Spondylitis Association of America (SAA) says that at least 300,000 and maybe up to one million people suffer with AK. SAA calls it more common than multiple sclerosis, cystic fibrosis and Lou Gehrig's disease combined. and Lou Gehrig's disease. The damage caused to the body by AK can spread to other joints including the hips and the shoulders.

Among treatment options, weight control is among the most important for anyone with arthritis, especially osteoarthritis. Excess weight puts added pressure on your weight-bearing joints. A study by the Arthritis Foundation found that overweight, middle-aged and older women can actually lower their risk of developing osteoarthritis of the knee by losing weight.

The Arthritis Foundation also recommends proper exercise for arthritis treatment. Exercises can develop range of motion, using gentle stretching, for example, to improve joint mobility. Strengthening exercises for muscles can also help stabilize joints. According to researchers at the National Institutes of Health, weakness of the quadriceps muscle (in front of the thigh) is common in patients with osteoarthritis and strengthening the quadriceps decreases the risk of osteoarthritis. In addition, there are a number of specific classes, such as water exercise or chair exercises, designed for people with arthritis. Always consult your doctor or physical therapist for information on the right type of exercise for your specific problem.

In addition, NIAMS says there are other therapies that may work for flare-ups of swelling and pain. These include:

• Heat and cold - The decision to use either heat or cold for arthritis pain depends on the type of arthritis and should be discussed with your doctor or physical therapist. Moist heat, such as a warm bath or shower, or dry heat, such as a heating pad, placed on the painful area of the joint for about 15 minutes may relieve the pain. Make sure you take all necessary precautions to avoid burning or otherwise hurting your skin, and if you have poor circulation, do not use cold packs.
• Joint Protection - Using a splint or a brace to allow joints to rest and protect them from injury can be helpful. Your physician or physical therapist can make recommendations.
• Transcutaneous electrical nerve stimulation (TENS) - A small TENS device that directs mild electric pulses to nerve endings that lie beneath the skin in the painful area may relieve some arthritis pain. NIAMS says TENS seems to work by blocking pain messages to the brain and by modifying pain perception.
• Arthroscopy may be used to help diagnose and treat some forms of arthritis, including osteoarthritis and rheumatoid arthritis.

The drugs used for treating arthritis and rheumatic diseases fall into several different categories. Among the non-steroidal anti-inflammatory drugs (NSAIDs) are aspirin, ibuprofen, naproxen sodium and ketoprofen. Many arthritis drugs are available over-the-counter; however long-term use of these products should never be undertaken without a doctor's advice. NIAMS says common side effects of NSAIDs, including those available over-the-counter, can include stomach upset, heartburn, diarrhea, and fluid retention. Some patients also develop liver and kidney inflammation while taking NSAIDs, making it especially important to stay in close contact with the doctor while taking these medications.

A class of drugs called COX-2 inhibitors, like NSAIDs, block COX-2, an enzyme in the body known to stimulate an inflammatory response. Unlike NSAIDs, however, they do not block the action of COX-1, which is an enzyme that helps to protect the stomach lining. Therefore, NIAMS says drugs in this category are believed to reduce joint pain and inflammation with reduced risk of gastrointestinal ulceration and bleeding. Again, however, there is concern about side effects, so discuss all treatment options with your doctor.

Disease-modifying anti-rheumatic drugs (DMARDS) are another type of drug used to treat people with rheumatoid arthritis who have not responded to NSAIDs. NIAMS says some of these include methotrexate, hydroxychloroquine, penicillamine and gold injections; all require careful monitoring by the physician to avoid side effects. A class of drugs called biologic response modifiers can also be used to treat rheumatoid arthritis. NIAMS says this class of drugs work by blocking the action of a substance called tumor necrosis factor (TNF). TNF is a protein of the body's immune system that can trigger inflammation. By binding TNF, these drugs can result in less inflammation.

Corticosteroids may also be used. These are hormones that can be taken by mouth or given by injection. Prednisone is the corticosteroid most often given by mouth to reduce the inflammation of rheumatoid arthritis. In both rheumatoid arthritis and osteoarthritis, the doctor also may inject a corticosteroid into the affected joint to stop pain. According to NIAMS, because frequent injections may cause damage to the cartilage, they should only be done once or twice a year.

NIAMS says corticosteroids are also an important part of treatment for lupus because they suppress the immune system and reduce inflammation. Because of the potential for some serious side effects, including osteoporosis and coronary artery disease, the use of corticosteroids must be carefully monitored. In general, corticosteroids should not be taken together with NSAIDS and aspirin. NIAMS says anyone using corticosteroids should talk to their doctors about taking supplemental calcium and vitamin D to reduce the risk of osteoporosis. Because of the risks of long-term corticosteroid use, researchers are trying to develop other drug therapies. Antimalarials have been found to help manage some of the symptoms of lupus. Treatment for lupus also involves avoidance of potential triggers for flare-ups, including exposure to sun, as well as stress.

When taking medication, it's important that you never mix different types of drugs. Even medications such as cold remedies may contain ingredients that can cause problems if taken in combination with other medications, so always read labels and talk with your doctor or pharmacist first. Corticosteroids may also be used for short periods for arthritis.

In addition, topical creams can be helpful. Many contain salicylates to reduce inflammation and pain. Other topical treatments may produce feelings of warmth or coolness on the skin to help provide relief. In addition, capsaicin (the substance found in hot peppers) is being used in some topical creams to provide pain relief. As with any medicine, always talk with your doctor before using, make sure you read and follow all package directions carefully, and keep all such medications out of children's reach.