From New World Encyclopedia
Classification and external resources
ICD-10 M00-M25
ICD-9 710-719
DiseasesDB 15237
MeSH D001168

Arthritis (plural, "arthritides") is a group of conditions where there is damage caused to the joints of the body, typically involving inflammation and pain.

Arthritis often is defined as inflammation of a joint. (Inflammation usually is indicated by using the English suffix "-itis," and the term arthritis comes from the Greek arthro-, joint + -itis, or inflammation.) However, there are many forms of arthritis and in some the sufferer may experience little or no inflammation.

Among the more than one hundred identified forms of arthritis are osteoarthritis (involving the deterioration of the cartilage that covers and acts as a cushion inside joints), rheumatoid arthritis (a chronic, inflammatory autoimmune disorder that causes the immune system to attack the joints), and gout or metabolic arthritis (a disease due to a congenital disorder of uric acid metabolism). The various forms of arthritis together comprise the most common chronic illness in the United States (Shiel 2019).

The presence of arthritis accentuates how harmoniously the human body normally functions. For the vast majority of people, for the vast majority of their lives, the joints in the body function remarkably smoothly, through a wide range of activities. Arthritis, with its diverse causes—such as injury, infection, abnormal metabolism, or hereditary diseases—represents a break in this normal harmony.


Joint abnormalities in rheumatoid arthritis

Arthritis is a disorder of the joint. A joint is the location at which two or more bones make contact. Joints are constructed to allow movement and provide mechanical support.

In a literal sense, arthritis means inflammation of one or more joints (Shiel 2019). Inflammation is a localized protective response of a body's living tissue to injury, infection, irritation, or allergy. It is characterized by the following quintet: Redness (rubor), heat (calor), swelling (tumor), pain (dolor), and dysfunction of the organs involved (functio laesa). Inflammation is part of the innate immune system, that is, the immediate "first-line" of defense to illness or pathogens. As such, inflammation is not "healthy" nor "unhealthy" on its own. For example, it may help fight disease or injury by removing pathogens and debris, and walling off infection from spreading. However, it comes at the cost of suspending the body's normal immune and catabolic processes. In the short term, this is often a valid trade-off, but in the long term it causes progressive damage. Inflammation is usually indicated by using the English suffix "-itis," such as appendicitis, laryngitis, pancreatitis, hepatitis, and encephalitis.

There are 100 or more different forms of arthritis (Shiel 2019; WebMD 2017). These differ widely according to cause, clinical course, appearance, and so forth. Rheumatoid arthritis and psoriatic arthritis are autoimmune diseases in which the body is attacking itself. Septic arthritis is caused by joint infection. Gouty arthritis is caused by deposition of uric acid crystals in the joint that results in subsequent inflammation. Additionally, there is a less common form of gout that is caused by the formation of rhomboidal shaped crystals of calcium pyrophosphate. This form of gout is known as pseudogout.

The most common form of arthritis, osteoarthritis, also known as degenerative joint disease, occurs following trauma to the joint, an infection of the joint, or simply as a result of aging. There is emerging evidence that abnormal anatomy may contribute to early development of osteoarthritis.

Many sufferers of osteoarthritis have little or no inflammation. Inflammation, soft tissue swelling, and the involvement of multiple joints are common signs and symptoms that distinguish rheumatoid and other inflammatory arthritis from non-inflammatory arthritis, such as osteoarthritis.

Types of arthritis

Primary forms of arthritis:

  • Osteoarthritis
  • Rheumatoid arthritis
  • Septic arthritis
  • Gout and pseudogout
  • Juvenile idiopathic arthritis
  • Still's disease
  • Ankylosing spondylitis

Secondary to other diseases:

  • Lupus erythematosus
  • Henoch-Schönlein purpura
  • Psoriatic arthritis
  • Reactive arthritis
  • Haemochromatosis
  • Hepatitis
  • Wegener's granulomatosis (and many other vasculitis syndromes)
  • Familial Mediterranean fever
  • Hyperimmunoglobulinemia D with recurrent fever
  • TNF receptor associated periodic syndrome
  • Inflammatory Bowel Disease (Including Crohn's Disease and Ulcerative Colitis)

Diseases that can mimic arthritis include:

  • Hypertrophic osteoarthropathy
  • Multiple myeloma
  • Osteoporosis
  • Fifth disease


All arthritides feature pain. Patterns of pain differ among the arthritides and the location. Osteoarthritis is classically worse at night or following rest. Rheumatoid arthritis is generally worse in the morning. In elderly people and children, pain may not be the main feature, and the patient simply moves less (elderly) or refuses to use the affected limb (children).

Elements of the history of the pain (onset, number of joints and which involved, duration, aggravating and relieving factors) all guide diagnosis. Physical examination typically confirms diagnosis. Radiographs are often used to follow progression or assess severity in a more quantitative manner.

Blood tests and X-rays of the affected joints often are performed to make the diagnosis.

Screening blood tests may be indicated if certain arthritides are suspected. This may include: Rheumatoid factor, antinuclear factor (ANF), extractable nuclear antigen, and specific antibodies.


Treatment options vary depending on the type of arthritis and include physical and occupational therapy, lifestyle changes (including exercise and weight control), and medications (symptomatic or targeted at the disease process causing the arthritis). Arthroplasty (joint replacement surgery) may be required with forms of arthritis that erode the bone.


While evidence of primary ankle (kaki) osteoarthritis has been discovered in dinosaurs, the first known traces of human arthritis date back as far as 4500 B.C.E. It was noted in skeletal remains of Native Americans found in Tennessee and parts of what is now Olathe, Kansas. Evidence of arthritis has been found throughout history, from Ötzi, a mummy (circa 3000 B.C.E.) found along the border of modern Italy and Austria, to the Egyptian mummies circa 2590 B.C.E.

ISBN links support NWE through referral fees

  • Shiel, W. C. 2019. Arthritis. Retrieved August 3, 2019.
  • Verbrugge, L. M. 1992. Disability transitions for older persons with arthritis. Journal of Aging and Health 4(2): 212-243.
  • WebMD. 2017. The basics of Arthritis Retrieved August 3, 2019.

External links

All links retrieved August 16, 2023.


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