Osteoarthritis can affect any joint, but it most often occurs in the knees, hips, spine and fingers. At first it may affect only one joint, but if the joint is in the fingers, multiple hand joints may become affected. The photo at right shows the hard, bony swellings (called Heberden's and Bouchard's nodes) in the finger joints that are typical of osteoarthritis.
People with osteoarthritis may have:
- Pain in a joint during or after use. The acute pain of early osteoarthritis often fades within a year but may come back if the joint is overused. The amount of pain varies from mildly inconvenient to disabling.
- Discomfort in a joint when the weather changes
- Swelling and stiffness in a joint, particularly after using it
- Bony knobs (nodes) on the finger joints may create a gnarled appearance. Early on, the joints may feel tender, painful or stiff. After one or two years, the pain often grows less, leaving just the nodes that affect the ability to move the finger joints. Nodes affect women more than men and tend to run in families.
- Back and neck pain and stiffness from slow deterioration of discs between the bones of the spine
Causes and Risk Factors
Some scientists believe the osteoarthritis may be due to a mechanical stress, which causes the cartilage cells or lining of the joint to release an imbalance of enzymes. When balanced, these enzymes allow for the natural breakdown and repair of cartilage, but too much of the enzymes can cause the joint cartilage to break down faster than it's rebuilt. Over time, the smooth cartilage protecting the ends of the bones at the joint wears down and gets rough. Eventually, if it wears down completely, the bone rubs against bone, damaging the ends of the bones and making joints painful.
The body works to repair the damage, but when these repairs don't work well, new bone may grow along the sides of the existing bone. This growth makes large lumps, most noticeable on the hands and feet. Each of the steps in this repair process produces pain. The pain and tenderness over the bony lumps may be most marked early in the disease and less so later on.
The risk of osteoarthritis is greater for those who:
- Are 45 or older
- Are women
- Have heredity conditions, such as defective cartilage and malformed joints
- Have joint injuries caused by work or sports
- Are obese
- Have diseases that change the structure and function of cartilage, such as rheumatoid arthritis, hemochromatosis (a condition in which iron collects in the body to dangerous levels), Paget's disease, gout or pseudogout