Arthritis, literally meaning joint inflammation, is a general term covering numerous conditions where the joint surface or cartilage wears out. The joint surface is covered by a smooth articular surface that allows pain free movement in the joint. This surface can wear out for several reasons; often the definite cause is not known.
When the articular cartilage wears out the bone ends rub on one another and cause pain. This condition is referred to as Osteoarthritis or “wear and tear” arthritis as it occurs with aging and use. It is the most common type of arthritis.
Causes of Arthritis
- Trauma (fracture)
- Increased stress such as overuse and overweight
- Infection of the bone
- Connective tissue disorders
- Autoimmune (Rheumatoid/psoriatic arthritis)
- Crystalline arthropathy (gout or pseudogout)
Knee Arthritis causes pain and decreased mobility of the knee joint. In the arthritic knee, there is damage to the cartilage that results in a narrowed or absent joint space on X-ray.
The cartilage lining is thinner than normal or completely absent. The degree of cartilage damage and inflammation varies with the type and stage of arthritis. The capsule of the arthritic knee is swollen. The joint space is narrowed and irregular in outline; this can be seen in on X-ray. Bone spurs can also build up around the edges of the joint. The combinations of these factors make the arthritic knee stiff and limit activities due to pain and fatigue.