What Is Arthritis?


Arthritis is a medical condition that involves inflammation and tenderness in one or more joints. Arthritis is an umbrella term used to refer to joint pain or joint disease; more than 100 types of arthritis have been identified.

What are the main types of arthritis?

The four main types of arthritis include the following:

  1. Degenerative arthritis —The cartilage between bones wears away, causing bone to rub against bone in the joint (e.g., osteoarthritis).
  2. Inflammatory arthritis — The immune system mistakenly attacks the joint, causing inflammation (e.g., rheumatoid arthritis).
  3. Infectious arthritis — A bacterial, viral, or fungal infection develops in the joint and causes inflammation (e.g., septic arthritis).
  4. Metabolic arthritis — Uric acid builds up in the blood and forms needle-like crystals in the joint (e.g., gout).

What are the symptoms of arthritis?

Arthritis can affect one joint or multiple joints throughout the body. Depending on the specific type of arthritis, symptoms vary and range from mild to severe. General symptoms include, but are not limited to, the following:

  • Joint pain
  • Joint tenderness
  • Joint swelling, redness, stiffness or warmth
  • Decreased range of motion
  • Locking of the joint
  • Weakness or loss of strength
  • Bone growths
  • Skin rashes or itchy skin

What causes arthritis?

Various genetic and environmental factors can cause arthritis. Many types of arthritis have a genetic component — they are passed down from one generation to the next. Inflammatory arthritis is caused by an overactive immune system, and metabolic arthritis is caused by metabolic abnormalities.

If a genetic predisposition to arthritis is present, environmental factors, such as illness or injury, may trigger the condition. For example, some types of arthritis can develop from a bacterial, viral or fungal infection. Osteoarthritis is commonly caused by age-related “wear and tear” or by a previous injury.

Who is at risk for developing arthritis?

People of all ages, genders and races can develop arthritis. More than 50 million adults and 300,000 children have arthritis or a related condition.

Rheumatoid arthritis is more common in women, but certain types of metabolic arthritis, such as gout, are more common in men. The risk of developing most types of arthritis increases with age. Other risk factors include a family history of arthritis, previous joint injury, and obesity.