A common cause for knee pain is age. Osteoarthritis of knee, commonly known as wear-and-tear arthritis, is a condition in which the natural cushioning between joints -- cartilage -- wears away. When this happens, the bones of the joints rub more closely against one another with less of the shock-absorbing benefits of cartilage. The rubbing results in pain, swelling, stiffness, decreased ability to move and, sometimes, the formation of bone spurs.
For treatment, massage, application of heat compress and acupuncture is recommended, with herbal medication as a supplement to aid blood circulation and reduce pain.