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What is osteoarthritis?

This article offers an introduction to osteoarthritis, including a helpful infographic, and a lay definition that is suitable for patients.

Osteoarthritis (OA) is the most common form of arthritis.

An introduction to osteoarthritis

Osteoarthritis is a:

  • Complex disorder of synovial joints, affecting all joint tissues
  • The clinical syndrome of joint pain, functional limitation, and impaired quality of life
  • Chronic disease with varying symptom severity. According to the Osteoarthritis Research Society International (OARSI):

“Osteoarthritis is a disorder involving movable joints characterised by cell stress and extracellular matrix degradation initiated by a micro or macro injury that activates maladaptive repair responses including pro-inflammatory pathways of innate immunity. The disease manifests first as a molecular derangement (abnormal joint tissue metabolism) followed by anatomic and/or physiologic derangement (characterised by cartilage degradation, bone remodelling, osteophyte formation, joint inflammation and loss of normal joint function) that can culminate in illness”

Here’s a helpful infographic to explain further.

OARSI infographic(Infographic by the Osteoarthritis Research Society International (OARSI))1

Lay definition of osteoarthritis

This is suitable for explaining osteoarthritis to your patients. 

Osteoarthritis is a disorder that can affect any moveable joint of the body, for example, knees, hips, and hands. It can show itself as a breakdown of tissues and abnormal changes to cell structures of joints, which can be initiated by injury. As the joint tries to repair, it can lead to other problems.

Osteoarthritis first shows itself as a change to the biological processes within a joint, followed by abnormal changes to the joint, such as the breakdown of cartilage, bone reshaping, bony lumps, joint inflammation, and loss of joint function. This can result in pain, stiffness and loss of movement. There are certain factors which make some people more vulnerable to developing osteoarthritis, such as genetic factors, other joint disorders (such as rheumatoid arthritis), injury to the joint from accidents or surgery, being overweight or doing heavy physical activity in some sports or a person’s job”.

Research User Group, Institute of Primary Care and Health Sciences, Keele University, UK

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Physiotherapy Exercise and Physical Activity for Knee Osteoarthritis (PEAK)

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