Arthritis - how a normal joint works

To understand how arthritis develops, you need to know how a normal joint works.

A joint is the place where two bones meet. Most joints are designed to allow the bones to move in certain directions.

A joint is surrounded by a joint capsule that protects and supports it. The capsule is lined with a membrane called synovium, which provides synovial fluid. This clear fluid lubricates and nourishes the cartilage and bones inside the joint capsule. the cartilage covers the ends of the two bones and acts as a kind of shock absorber when you put weight on the joint. The smooth, slippery cartilage surface allows the bone ends to move freely.