Understanding Arthritis -- the Basics

What Is Arthritis?

Arthritis includes a variety of inflammatory and noninflammatory joint diseases such as osteoarthritis, gout, rheumatoid arthritis, and juvenile rheumatoid arthritis.

Although the term arthritis is applied to a wide variety of disorders, arthritis means inflammation of a joint, whether the result of a disease, an infection, a genetic defect, or some other cause.

Arthritis inflammation causes pain, stiffness, and swelling in the joints and surrounding tissues. Many people mistakenly perceive arthritis as any kind of pain or discomfort associated with body movement, including low back pain, bursitis, tendinitis, and general stiffness or pain in the joints. However, these symptoms may not be caused by arthritis. A doctor needs to confirm a diagnosis of arthritis.

For many, but not all, arthritis seems to be an inevitable part of aging. While there are no signs of long-lasting cures in the immediate future, advances in both conventional medical treatment and alternative therapies have made living with arthritis more bearable.

The Major Types of Arthritis

Osteoarthritis , or degenerative joint disease, refers to the pain and swelling that can result from the progressive loss of cartilage in the joints. It is the most common form of arthritis, affecting more than 30 million adults in the United States, particularly older adults. In osteoarthritis, the protective cartilage that cushions the ends of bones within joints gradually wears away, which is why it is sometimes called "wear and tear" arthritis. It can affect almost any joint in the body, but commonly involves the weight-bearing joints: the knees, hips, and spine. It can also affect the fingers and any joint with previous injury from trauma, infection, or inflammation. The inner bone surfaces become exposed and rub together, and in some cases, bony spurs develop on the edges of joints, causing damage to muscles and nerves, pain, deformity, and difficulty moving.

Although the mechanism behind osteoarthritis is unknown, some people appear to have a genetic predisposition to degenerative joint disorders. This is often the case for people who develop it at an early age. Other causes of osteoarthritis include:

  • Misuse of anabolic steroids (used by some athletes)
  • Trauma to joint surfaces
  • Being overweight, which can cause early and more rapid progression of joint problems, especially in the knee


In many people, the onset of osteoarthritis is gradual and has no serious debilitating effect in the beginning, although it can change the shape and appearance of a joint. Bony growths called spurs may cause painful nerve damage, especially if they involve the spine, and may lead to significant changes in posture and mobility.

Rheumatoid arthritis can occur at any age, but generally begins to affect people between ages 30 and 50. It affects women two to three times more often than men. It is the second most common form of arthritis, affecting 1.3 million people in the United States. Rheumatoid arthritis is characterized by inflammation, swelling, and pain in the hands, especially the knuckles and next closest finger joints, as well as in the wrists, elbows, shoulders, knees, and feet. Generalized fatigue can also occur. Rheumatoid arthritis can also cause damage to other parts of the body, including the lungs, eyes, nerves, and skin. The discomfort of rheumatoid arthritis usually develops and worsens over weeks or months and tends to be most severe upon awakening.

Rheumatoid arthritis may eventually cause the hands and feet to become misshapen as muscles weaken, tendons move out of position, and the ends of bones become damaged.

Though there is no cure, remission is possible. Early treatment of rheumatoid arthritis can relieve symptoms and prevent disability in most people. With early treatment, the likelihood of permanent disability is reduced in all but 5% to 10% of sufferers.

Juvenile rheumatoid arthritis comes in many forms. Still's disease, one type of arthritis, affects the whole body. It is characterized by daily fevers and low blood counts (anemia). The disease can also have secondary effects on the heart, lungs, eyes, and nervous system. Other kinds of juvenile rheumatoid arthritis is characterized by persistent arthritis in one or more joints. Treatment is essentially the same as for adult rheumatoid arthritis, with heavy emphasis on physical therapy and exercise to keep growing bodies active. Permanent damage from juvenile rheumatoid arthritis is now rare, and most affected children recover from the disease fully without experiencing any lasting disabilities.


The cause of rheumatoid arthritis is not fully understood, but it is an autoimmune disorder. In autoimmune disorders the body's immune system wrongly attacks itself. Rheumatoid arthritis is not contagious and cannot be spread from one person to another. Some people may have a genetic or inherited factor that makes them more likely to develop rheumatoid arthritis.

Infectious arthritis is caused by a bacterial or viral infection. It is typically caused by infection that travels to a joint from other parts of the body. It can affect, fingers, toes, and arm and leg joints. Examples include staph infection, tuberculosis, gonorrhea, or Lyme disease. It can also be a complication of injury where the organism is directly introduced into the joint.

Other arthritic conditions include ankylosing spondylitis (an inherited arthritis of the spine), bone spurs (bony growths on the vertebrae or other areas), gout (a form of crystal-induced arthritis), and systemic lupus (inflammatory connective-tissue disease).

WebMD Medical Reference Reviewed by David Zelman, MD on January 30, 2019



American College of Rheumatology. 

DePuy Orthopaedics. 

National Institute of Arthritis and Musculoskeletal and Skin Diseases. 

Arthritis Foundation. 

Markkula Center for Applied Ethics, Santa Clara University. 


National Institutes of Health. 

The Center for Current Research. 

National Internet Health. 

Alternative Medicine Foundation. 

CDC: "Osteoarthritis (OA)."

Rheumatoid Arthritis Support Network.


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