Osteoarthritis (OA) is also known as ‘wear and tear’ arthritis or degenerative arthritis. Particularly affects the weight-bearing joints e.g. hips and knees.

 

Affects men more than women.

 

It is associated with obesity and ageing and there can be a genetic link.

 

Often affects specific  joints because of injury or excessive wear and tear on the joint

 

Disease process

1. Damage to the articular cartilage is usually due to trauma or excess stresses on the joint. This causes cracks to form in the articular (hyaline) cartilage and gradual erosion (wear and tear). This can also occur for unknown reasons

2. The surface of the cartilage gradually becomes rough and worn causing joint stiffness and reduced joint movement

3. Enzymes are released by the cells in the damaged tissue which speeds up this process of breakdown of the cartilage

4. Eventually, the bone becomes exposed and damaged. This can result in the formation of cysts and osteophytes/bony spurs at the joint margins due to new bone growth.

5. These osteophytes can break off and get lodged in the joint causing it to lock. They can also cause further irritation in the synovial cavity. Extra bone growth causes the joint to appear enlarged

6. The gradual breakdown of cartilage results in narrowing of the joint space

7. The muscles surrounding the joint can become weak and atrophy (wasted) causing instability and difficulty walking

8. Crepitus (a grating sound) can occur due to the irregularly shaped cartilage and bone rubbing on each other.

9. The joint becomes irritated due to no longer having a layer of cartilage to protect the bone causing pain and swelling