Osteoarthritis is a degenerative disease that causes the knee cartilage to wear down. Osteoarthritis may be caused by excess stress on the joint and causes pain, swelling, and a decrease in knee motion. A common symptom is morning stiffness that decreases with use. The knee may also pop of click, or even lock up at times.

Osteoarthritis of the knee is treated with pain-reducing medicines, such as aspirin or acetaminophen(Tylenol) nonsteroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen (Motrin, Nuprin, Advil) and exercises to strengthen the knee.