What Causes Osteoarthritis?

Pathophysiology-What Happens In Osteoarthritis?

The main cause of Osteoarthritis is an imbalance in the natural breakdown and repair process that occurs with cartilage.  In Osteoarthritis, damaged cartilage cannot repair itself in the normal way. It occurs when the cartilage that covers and cushions the ends of bones in your joints deteriorates over time.  Cartilage is composed of water, collagen, and specific proteins.

In healthy cartilage, there is a continual process of natural breaking down and repair of the cartilage in joints. This process becomes disrupted in Osteoarthritis, leading to cartilage deterioration and an abnormal repair response.  The reason this normal repair process is disrupted is not known but it is likely caused by several factors.

With aging, the water content of the cartilage increases, and the protein makeup of cartilage breaks down.

Eventually, the smooth surface of the cartilage begins to deteriorate and become worn causing friction between the bones.  If the cartilage wears down completely, the result will be bone to bone contact. Repetitive use of worn joints over the years can irritate the cartilage, causing joint pain and inflammation of surrounding tissues. As pieces of cartilage break off, the bones thicken and broaden, causing inflammation. This inflammation may stimulate new bone outgrowths called spurs (also called osteophytes) to form around the joints. As the bones thicken and broaden, joints become stiff, painful, and may be difficult to move. Fluid may also build up in your joints.