You Are Here: Home > About Arthritis > What is Arthritis
What is Arthritis

What is Arthritis

Arthritis is a term used to describe a group of over 100 diseases characterized by inflammation in the joints or other areas of the body. Inflammation is a medical term that describes pain, stiffness, redness and swelling. Left unchecked, inflammation can lead to significant and often irreparable damage to the affected areas, resulting in loss of function and disability.

Arthritis (arthro = joint, itis = inflammation) can involve almost any part of the body, most often affecting the hip, knee, spine or other weight-bearing joints, but also found in the fingers and other non-weight-bearing joints. Some forms of arthritis can also affect other parts of the body.

Arthritis is a chronic condition: it affects people on an ongoing, constant or recurring basis over months, years, even a lifetime.

Types of arthritis

Arthritis conditions are grouped into two broad categories:

Osteoarthritis (OA)

Osteoarthritis (OA) is the most common type of arthritis, affecting more Canadians than all other forms of arthritis combined. Though once referred to as the “wear-and-tear” arthritis, the Osteoarthritis Research Society International (OARSI) recently re-defined this condition. It describes OA as the result of the body’s failed attempt to repair damaged joint tissues*. While the joint damage can occur through deterioration associated with aging, it can also occur in response to an injury.

OA leads to the breakdown of cartilage (the tough elastic material that covers and protects the ends of bones), and the resulting bone-on-bone contact can cause pain, stiffness, swelling and reduced range of movement in the affected joint(s). The joints most commonly affected by OA are the knees, hips and those in the hands and spine.

There are many factors that are thought to contribute to developing OA, such as age, obesity, your sex, occupation, participation in certain sports, history of joint injury or surgery, and genetics. For more information, visit our osteoarthritis page. 

Learn more about osteoarthritis

*Osteoarthritis Research Society International (OARSI)

Inflammatory arthritis (IA)

Inflammatory forms of arthritis are different from osteoarthritis, in that the source of joint damage is from inflammation rather a wearing away of your cartilage. Most forms of IA are also autoimmune diseases, where the immune system – the body’s defense system against infections and other invaders – mistakenly starts to attack the body’s own healthy tissues.

Inflammation from these conditions can result in pain, stiffness, restricted mobility, fatigue and damage to joints and other tissues. If not identified and treated swiftly, these conditions tend to progress more quickly and aggressively than OA.

IA includes every form of arthritis except osteoarthritis – even some things you may not have realized were arthritis at all, like lupus or gout. Other common examples include rheumatoid arthritis, ankylosing spondylitis, psoriatic arthritis and juvenile idiopathic arthritis, but there are many other types. Some forms of IA are considered systemic diseases, because they can affect the whole body. For more information, visit our inflammatory arthritis page. 

Learn more about inflammatory arthritis

Living with arthritis?

Arthritis symptoms can range from mild to severe. Most people with arthritis experience chronic pain, fatigue, restricted mobility, lowered mood and other symptoms that can combine to erode their quality of life.

Many forms of arthritis can lead to episodic disability, leaving people unable to work for periods of time due to their disease.

For millions of Canadians, arthritis can threaten their ability to enjoy freedom of movement, productive work, restful sleep, and an existence free of unnecessary pain.