A Joint is made up of two or more bony surfaces lined by a cartilage (padding)which acts as a shock absorver and allows smooth movement.

The ends of the bones are held together by a joint Capsule which is lined by a synovial membrane this produces the synovial fluid which helps in lubricating the joint and facilities smooth movement .A number of inflammatory and degenerative (collectively called arthritis)can cause damage to the cartilage and syovium.

Since the cartilage does not have blood supply and cannot repair itself-with continued damage it is worn away –exposing the bony ends.

The bony ends grind against each other with every movement of the joint and may produce stiffness and pain.