Arthritis
Introduction
The Tin Man was lucky. Just a squirt of oil on his stiff joints and he was able to dance down the yellow brick road with Dorothy. But for the 46 million Americans who have stiff aching joints due to arthritis, managing the condition is not as simple.
Arthritis is the general term for at least 100 rheumatic diseases that painfully affect joints, muscles, and connective tissues throughout the body. More than just a physical disease, arthritis drains patients emotionally and financially. It is the number one cause of disability in the United States. For millions of Americans with severe arthritis, pain and deformity limit such everyday activities as getting out of bed, climbing stairs, dressing, or simply walking. And, because it is a chronic disease, it is fertile ground for hundreds of alternative and unproven therapies.
What is it?
Arthritis is pain, swelling and stiffness of the joints. Joints are parts of the body where two bones are attached and are usually lined with cartilage, a rubbery material that prevents the bones from rubbing together. Arthritis can result from too much wear and tear on the joint or from illnesses that cause inflammation of the joint. While some types of arthritis are acute, meaning that they come on suddenly and don't last forever, most are chronic, coming on gradually and persisting for a long time.
What causes it?
Little is known about what causes most types of arthritis. The following can cause arthritic diseases:
· an overly active immune system that results in your body attacking itself
· imbalances in your body's chemistry that allow certain chemicals to build up in your body and get deposited into your joints
· injuries
· birth defects
· heredity-some types of arthritis run in families
· infections
· wear and tear on the joints
In normal joints, muscle, tendons and bursa (a pad-like sac) support bones. The joint's inner lining, the synovium, lubricates it by releasing a slippery fluid. Cartilage cushions the ends of the bones, keeping them from rubbing together during normal movement. In osteoarthritis, the cartilage breaks down and the bones rub together. Bone ends may thicken and form growths called spurs. The joint then loses its normal shape; joint alignment changes, and pieces of cartilage or bone may float in the joint area, causing pain and making movement difficult. Rheumatoid arthritis is believed to be the result of a malfunctioning immune system. Elements of the body's immune system fail to recognize natural body chemicals as "normal" and attack these chemicals as if they were a foreign material. The joint lining thickens as it becomes inflamed and damages cartilage and bone, sometimes causing deformity.
Normal joints are cushioned by cartilage and
a fluid lubricant. In arthritis, the cartilage and
bone erode.
Who has it?
An estimated 46 million Americans have some form of arthritis. Women are affected more often than men, accounting for about 3 out of every 5 cases of osteoarthritis or rheumatoid arthritis. Although arthritis is most common in elderly people, almost 300,000 American children suffer from it as well.
Arthritis frequently affects people in their most productive years. Osteoarthritis and rheumatoid arthritis cost the United States economy nearly $128 billion annually in medical expenses and expenses such as lost wages and production.
What are the risk factors?
Risk factors are characteristics that predispose people to developing a disease. The primary risk factors for arthritis are:
· aging
· family history
· being female
· a history of damage to the joint
· obesity
What are the symptoms?
Symptoms of arthritis include:
· tenderness
· pain
· stiffness
· decreased range of motion
· uncomfortable joint sensations
In some cases, fever or skin rash can accompany joint symptoms. The two most common types of arthritis are:
1. Osteoarthritis - a degenerative disease causing your body's cartilage to deteriorate, leaving bone to rub against bone. Our bodies are like any other machine: the moving parts, that is, our joints, need some kind of cushioning and lubrication so that the bones do not grate against each other every time we move. In normal joints, bones are supported by muscle, tendons, and bursa, which are sacs containing lubricating fluid. The joint's inner lining, called its synovial membrane, lubricates the joint by releasing a slippery fluid known as hyaluronic acid. Cartilage cushions the ends of the bones and keeps them from rubbing together during normal movement. In osteoarthritis, the cartilage breaks down and the bones rub together. Bone ends may thicken and form growths called spurs. The joint then loses its normal shape, joint alignment changes, and pieces of cartilage or bone may float in the joint space. The causes of this cartilage breakdown may be normal wear and tear, birth defects, genetics, infection, or injury.
2. Rheumatoid Arthritis-inflammation of the joint lining, called synovium, which leads to joint deterioration. Rheumatoid arthritis is a chronic disease characterized by general ill health and chronic inflammation of the tissues around the joints and tendons. It is a relatively common disease, affecting 2% of the population. It appears to have genetic origins. However, environmental factors may play a role. It has been found, for example, that its incidence changes in a particular population group with changes in their environment, like moving from the country into the city. This serious disease can be fatal when vital body organs are affected. In the absence of effective treatment, many patients experience significantly reduced mobility and function after they have had the disease for 10 years. Rheumatoid arthritis is believed to be the result of an autoimmune response. Elements of the body's immune system, the white blood cells known as T-cells, fail to recognize natural body chemicals as normal and attack these chemicals as if they were invaders, or antigens. When rheumatoid arthritis affects the joints, the immune system first attacks the synovium. This is the tissue lining the joint. The joint lining thickens as it becomes inflamed and damages cartilage and bone. Enzymes released during the inflammatory process damage the joint further.
Our immune system is a complex organization of cells and signaling chemicals known as cytokines that are designed to target and destroy invaders, like bacteria, viruses and foreign bodies. To defend the body, our immune system has to learn to recognize self and non-self. It does so by learning to recognize pieces of the foreign invader, known as antigens. If for some reason, the body loses its ability to differentiate self from non-self, then the immune system attacks its own tissue in addition to outside invaders. This is known as an auto-immune reaction.
When the immune system mistakes natural body chemicals for foreign substances, it may attack normal body tissues.
Scientists do not yet understand how this happens. For an immune reaction to occur, the tissue must be sending out a chemical signal that identifies it as an invader. Some scientists theorize that this signal could be the result of a genetic defect. Others believe that the body may have had an unknown viral or retroviral infection that left antigens in the tissue which identify it as foreign.
Rheumatoid arthritis causes disease both in the joints and other body organs. The joint disease first manifests itself as an inflammatory disease that is characterized by pain, morning stiffness, fever, and swelling of the joints. With time, the disease becomes chronic, and the underlying cartilage and bone in the joints are damaged. The bone becomes thinner, and the cartilage becomes narrow and worn away. Once cartilage has been lost, the damage is irreversible. Over time, the inflammation starts to subside, but by this time the joints are deformed and function deteriorates.
Other organs can be involved. Some patients can suffer from anemia, either from the disease, or from side effects of drug therapy. Other patients develop pericarditis, or inflammation of the lining around the heart. When nerve tissue is compressed as a result of joint damage, patients experience conditions like carpal tunnel syndrome. Some patients develop nodules under their skin, usually behind the elbow and at the back of their forearms. These nodules are sometimes a sign of more serious disease.
Other types of arthritis include:
· Gout-a recurrent inflammation of the joints, frequently the big toe. The patient most often recognizes gout because it commonly manifests itself with pain and inflammation of the big toe. It can, however, be found in other joints. Gout occurs when the kidneys are unable to eliminate uric acid from the body. This results in the build-up of uric acid crystals that concentrate in the joints. Gout has traditionally been identified as the arthritis of rich living, because it is associated with over-indulgence in alcohol and rich foods. This assumption may be incorrect; nevertheless, doctors advise their patients to drink a lot of liquids, avoid alcoholic beverages, and eat smaller amounts of protein-rich foods. Gout is usually treated with anti-inflammatory medications.
· Psoriatic arthritis-a type of joint inflammation that occurs in patients with psoriasis, a skin condition characterized by red, scaly or itchy patches of skin
· Spondyloarthritis-inflammation of the spine
· Viral or post-viral arthritis-joint inflammation related to a virus
· Septic arthritis-arthritis caused by bacterial infection
How is it treated?
The treatment of arthritis depends on the kind of arthritis being treated.
* Treating Osteoarthritis
* Treating Rheumatoid Arthritis
Drug classes used to treat Arthritis
Antimetabolites
Biologic Response Modifiers
COX-2 Inhibitors
Corticosteroids
Disease Modifying Antirheumatic Drugs
Miscellaneous Analgesics and Antipyretics
Non-steroidal Anti-inflammatory Drugs
Salicylates
What is on the horizon?
Although the present generation of medications for arthritis can help control the disease, most have side effects, and none, so far, can provide a cure. As a result, research into the various kinds of arthritis diseases is ongoing, as scientists attempt to devise more effective tactics to fight the disease.
While there are several medications available to treat the symptoms of osteoarthritis, currently none of the available treatments have the ability to stop or reverse the progression of damage to the joints. Researchers are presently studying several drugs that have the potential to decrease cartilage destruction in the joints of patients with osteoarthritis. There is also research underway to study new compounds that would treat the symptoms of osteoarthritis while causing fewer side effects.
To design drugs that can interrupt the cascade of reactions that cause an immune system disorder like rheumatoid arthritis, researchers try to identify the enzymes that are involved in the process. Once an enzyme is identified, researchers use sophisticated microscopic techniques to identify its structure. When the structure is known, scientists can design drugs that will bind with an active site in the enzyme, and thus short-circuit the process.
References
American College of Rheumatology Subcommittee on Rheumatoid Arthritis Guidelines. Guidelines for the management of rheumatoid arthritis. Arthritis & Rheumatism 2002; 46(2): 328-346. Available online: http://www.rheumatology.org/publications/guidelines/raguidelines02.asp Accessed March 2006
American College of Rheumatology Subcommittee on Osteoarthritis Guidelines. Recommendations for the medical management of osteoarthritis of the hip and knee. 2000 update. Arthritis & Rheumatism 2000; 43(9):1905-1915. Available online: http://www.rheumatology.org/publications/guidelines/oa-mgmt/oa-mgmt.asp Accessed March 2006
Arthritis Foundation. The Facts About Arthritis.
http://www.arthritisfoundation.org/resources/gettingstarted/default.asp Accessed January 2008.
CDC Arthritis Data and Statistics. Available at: http://www.cdc.gov/arthritis/data_statistics/arthritis_related_statistics.htm Accessed January 2008.
Clegg DO, Reda DJ, Harris CL, et al. Glucosamine, Chondroitin Sulfate, and the Two in Combination for Painful Knee Osteoarthritis. NEJM 2006;354:795-808.
Strange, C. Coping with Arthritis in Its Many Forms. U.S. Food and Drug Administration. http://www.fda.gov/fdac/features/296_art.html. Kineret [package insert]. Thousand Oaks, CA: Amgen, Inc.; October 2002.
Schuna AA. Rheumatoid Arthritis. In: Pharmacotherapy: a pathophysiologic approach. 6th ed. Dipiro JT, Talbert RL, Yee GC et. al., eds. New York: McGraw-Hill; 2005:1671-1683.
Hansen KE and Elliott ME. Osteoarthritis. In: Pharmacotherapy: a pathophysiologic approach. 6th ed. Dipiro JT, Talbert RL, Yee GC et. al., eds. New York: McGraw-Hill; 2005:1685-1703.
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