The simple version
Every moving joint has a smooth, slippery layer on the ends of the bones called cartilage. It lets the bones glide over each other without pain. In osteoarthritis, that layer gradually wears thinner, the joint becomes less smooth, and the tissues around it — bone, lining and muscle — react to the change. The result is pain, stiffness and a joint that does not move as freely as it used to.
It is often described as “wear and tear”, but that is not quite right. A joint is living tissue that repairs itself. Osteoarthritis develops when the damage happens faster than the repair can keep up — which is exactly why treating it early makes such a difference.
Which joints it affects
Osteoarthritis can affect any moving joint. The most commonly affected are the knees, hips, shoulders, ankles, wrists and hands, and the small facet joints of the spine.
Common signs
- Pain that gets worse with activity and eases with rest
- Stiffness, especially in the morning or after sitting still
- Swelling around the joint
- Reduced range of motion — the joint will not bend or straighten fully
- A grating, clicking or grinding feeling when you move
Why it happens
There is rarely one single cause. Age, extra body weight, a previous injury, repeated heavy loading of a joint, weak surrounding muscles and family history all raise the risk. Women are affected more often than men.
The four grades
Clinicians describe osteoarthritis in four grades, from earliest to most advanced. Knowing the grade helps decide which treatment is likely to work.
The good news
Osteoarthritis is common, but it is not inevitable and it is not untreatable. Caught early, progression can be slowed and mobility protected — and in most cases, without surgery. That is the work of the Global Joint Care Network.