osteoarthritis
Meaning of osteoarthritis: Calling it wear and tear undersells it, since cartilage cells actively dismantle their own matrix and the bone changes alongside.
Definition of osteoarthritis
Osteoarthritis is a disorder of the whole joint in which the cartilage capping the bone ends thins and breaks up, the bone beneath thickens and grows spurs at the margins, and the joint lining becomes mildly inflamed. Stiffness after rest, pain worsening with use and loss of movement follow. Knees, hips, hands and the spine are the joints most often affected.
Is it really just wear and tear?
That description is far too passive. Cartilage is not an inert cushion but living tissue maintained by cells that continually build and replace the collagen and water-binding molecules around them. In osteoarthritis those same cells shift toward breaking the matrix down, releasing enzymes that cut it apart faster than it is rebuilt. The surface roughens, then thins, then wears through to bone. Meanwhile the bone underneath thickens, fluid-filled cysts appear within it, new bone grows outward at the joint margins as spurs, and the joint lining releases inflammatory signals. The joint fails as a whole organ, and the chondrocyte is an active participant rather than a bystander.
How does it differ from rheumatoid arthritis?
| Feature | Osteoarthritis | Rheumatoid arthritis |
|---|---|---|
| Underlying process | Cartilage breakdown, mild inflammation | Immune attack on the joint lining |
| Morning stiffness | Brief, easing with movement | Prolonged |
| Pattern of joints | Often one sided, weight bearing | Symmetrical, small joints of hands and feet |
| Hand joints involved | Finger ends and the thumb base | Knuckles and middle finger joints |
| Blood tests | Normal | Inflammatory markers and antibodies raised |
The two can coexist, and rheumatoid arthritis leaves joints damaged in a way that afterward behaves like osteoarthritis, so the distinction concerns the process rather than which arrived first.
What makes it more likely?
Age is the strongest single factor, because the changes accumulate over decades. Previous injury matters greatly, since a torn ligament or a fracture running into a joint surface alters how load is distributed and brings the process forward by years. Body weight acts both mechanically at the knee and hip and chemically, because fat tissue releases inflammatory signals reaching every joint, including the hands. Joint shape counts, as with a shallow hip socket or a bowed knee. Work demanding repeated kneeling, squatting or heavy lifting raises risk in the joints it loads. Family history contributes, particularly for the hand form.
Also known as
Used in a sentence
Radiographs showed joint space narrowing and osteophytes consistent with osteoarthritis.
Good to know
The -itis ending overstates the inflammation, which is mild compared with rheumatoid arthritis, and the extent of change visible on an X-ray corresponds only loosely with the amount of pain a person reports.
Word origin
Where “osteoarthritis” comes from
From the Greek osteon, bone, and arthron, joint, with the suffix -itis, inflammation, although the inflammation involved is modest.