Knee osteoarthritis is a common condition in which changes in the knee joints lead to pain and difficulty walking. Treatment aims to relieve symptoms and maintain function. Treatments include drugs to decrease pain and inflammation; weight loss, if needed; physical therapy; and exercise. Unfortunately, these treatments do not always help, and some have side effects. Consequently, many people with knee osteoarthritis seek alternative treatments, such as acupuncture. Acupuncture is an ancient Chinese treatment that involves putting special needles into specific points of the body to treat medical conditions. Mainstream medicine is increasingly recognizing acupuncture as an effective treatment for some disorders. Past studies about acupuncture for osteoarthritis have been small and have had inconsistent results.