The tissues which are involved most in degenerative joint disease are the cartilage as well as the underlying subchondral bone. The cartilage refers to the smooth white material which forms over both the ends of the bones. It forms the moving surface of the joint on both the sides. Cartilage is tough, elastic, durable, and is comprised of collagen as well as water molecules.
As we age, and with activity as well as the use of a joint, the cartilage tends to become frayed, injured, even torn, and can even wear away entirely. In case this occurs, the bone surface on one side of the joint may rub or glide against the bone which is on the opposite side of the joint, which provides a less elastic joint surface. This tends to generate higher contact pressures at the end of the bone. Over time, these contacting bone surfaces can become hardened.
There are three common forms of degenerative joint disease, and many people tend to have some of each type. All people may develop OA to some degree, which will involve one or more joints, through their lifetime, as their aging process advances. The most common sites for degenerative joint disease include the base of the thumb joint, the knees, as well as the hands.
The mildest form of degenerative joint disease causes bony enlargement of the finger joints. In this condition, the end joints of the fingers will become bony. The hand will begin to assume the appearance of old age; due to a swollen joint which will involve the fingers. The base of the thumb can become swollen along with bony enlargement, which is the most frequently encountered site of OA.
Another form of degenerative joint disease involves the spine. Bony growths tend to appear on the spine in the neck region or even in the lower back. This process of OA in the spine begins along with a degeneration of the cartilage which is in the disc spaces.