By Dr. Brian McDonough, Medical Editor

PHILADELPHIA (CBS) – Although it can occur in almost any joint, osteoarthritis is a condition that often occurs most commonly in the knee.

As the protective cartilage in the joints wears down over time – it’s more common in people over 50 and people who are overweight – it starts to wear away. The cartilage actually acts like a cushioning surface in the body and when it’s damaged a person can actually have 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.

Pain medicine can help, as well as physical therapy. Exercise and weight loss can make a big difference, as can sports which are less traumatic.