By Dr. Brian McDonough

By Dr. Brian McDonough, Medical Editor

PHILADELPHIA (CBS) – Osteoarthritis is a condition that usually involves the knee and can affect many people as they get older.

In osteoarthritis the protective cartilage in the joints wears down over time. It’s more common in people over 50 and people who are overweight, but cartilage can wear away in virtually anyone.

Cartilage acts like a cushioning surface in the body and when it’s damaged a person can end up with areas of a joint where bone rubs against bone. The most common symptom is, not surprisingly, pain.

In addition, with activity, there is a limited range of motion, stiffness, tenderness, and swelling around the knee. Often, people will say they feel as if the knee is going to give out.

Exercise and weight loss can make a big difference, as can sports which are less traumatic. Of course, in many cases medication is needed.