Human Body: When Joints Wear Out

When the cartilage in a joint wears down, tiny pieces break off.  These little pieces cause the joint to become inflamed, so it produces extra joint fluid—leading to a painful, swollen joint.

When the cartilage becomes too damaged, the ends of the bone begin to rub together.

Sometimes, the bone under the damaged cartilage begins to disintegrate. 

With some types of arthritis, the joint fills up with scar tissue.  With other types, the ends of the bones thicken and form growths called “bone spurs”.

As a joint becomes more diseased, the bones may not line up right, causing the joint to be deformed.

When a joint is painful, people tend to favor it by not moving it.  This causes the muscles around the joint to weaken and shrink.  These weak muscles won’t give the joint proper support—causing more pain!