What is arthritis?

Arthritis is a term that includes more than 100 diseases characterized by inflammation of the joints and other parts of the body. The inflammation is a medical term pain, stiffness, redness and swelling. If left unchecked, inflammation can cause significant, often permanent, damage to affected areas, resulting in loss of function and disability.

Arthritis (from the roots “arthro”, which means joint, and “itis”, which means inflammation) can affect virtually any part of the body, but it most often attacks the hips, knees, spine or other bearing joints. The disease can, however, affect the fingers and other non-bearing joints.

Arthritis is a chronic disease , which means it affects people who have it continuously, permanently or recurrently for periods ranging from months to a lifetime.

Types of arthritis

Arthritis diseases and conditions are two broad categories.


Osteoarthritis is the most common form of arthritis. It affects more Canadians than all other forms of arthritis combined. Although once considered a normal deterioration and wear and tear disease, Osteoarthritis Research Society International (OARSI) has recently redefined it. The organization describes osteoarthritis as the body’s inability to repair damaged joint tissues *. Although joint damage can occur as a result of the deterioration associated with aging, it can also result from an injury.

Osteoarthritis leads to the deterioration of cartilage (the solid elastic material that covers and protects the ends of bones). This results in bone rubbing against each other causing pain, stiffness, swelling and reduced range of motion. The joints most commonly affected by osteoarthritis are the knees and hips, as well as the joints of the hands and spine.

Many factors would contribute to the development of osteoarthritis, such as age, obesity, gender, occupation, participation in certain sports, joint injuries or operations, and genetics.

For more information, visit our page on osteoarthritis .

* The Osteoarthritis Research Society International (OARSI)

Inflammatory arthritis

Inflammatory arthritis (IA) forms are distinguished from osteoarthritis, since inflammation, rather than cartilage wear, is the source of joint damage. Most forms of AI are also autoimmune diseases, that is, the immune system – the body’s defense system against infections and other invaders – mistakenly attacks healthy tissue.

Inflammation associated with these conditions can cause pain, stiffness, restricted mobility, fatigue, and damage to joints and other tissues. If they are not detected and treated quickly, these diseases tend to progress more rapidly and more aggressively than osteoarthritis.

AI includes all forms of arthritis except osteoarthritis – even some diseases that you may not associate with arthritis, such as lupus  or gout . Common forms of AI include rheumatoid arthritis , ankylosing spondylitis , psoriatic arthritis and juvenile idiopathic arthritis . There are, however, many other lesser known examples. Some forms of AI are considered systemic because they can affect the whole body.

For more information, visit our page on inflammatory arthritis . 

Do you live with arthritis?

The symptoms of arthritis can be mild to severe. Most people with arthritis have to deal with chronic pain, fatigue, restricted mobility, moodiness and other symptoms that, together, erode their quality of life.

Many forms of arthritis can lead to episodic disability, which then prevents people from working for certain periods.

Arthritis threatens the ability of millions of Canadians to have freedom of movement, to work productively, to get restful sleep, and to live a life free from unnecessary pain.