When oral medications do not relieve knee pain, but you're not to the point of pursuing knee surgery, one of the following injections or procedures may help.

Hyaluronic acid supplements – Although not technically medications, these substances are injected into knee joints to supplement naturally occurring hyaluronic acid. In healthy joints hyaluronic acid acts as a shock absorber and lubricant, allowing joints to move smoothly over each other. However, the acid appears to break down in people with osteoarthritis. Injecting it into a joint may lessen pain and inflammation. The injections are given weekly for three or five weeks, depending on the product (examples are Synvisc and Hyalgan). A small amount of joint fluid is removed first to make room for the hyaluronic acid.

Corticosteroid Injections – Doctors sometimes inject corticosteroids directly into the knee joint for quick relief of pain and inflammation. Their benefits may last anywhere from a few days to more than six months. While the injections bring targeted relief to the joint and lack many of the side effects of oral corticosteroid medications, they are not without risks. Repeated knee injections may actually contribute to cartilage breakdown. For that reason your doctor will likely put a limit on the number of injections you can receive.

Read a report from the British Medical Journal on corticosteroid injections for knee osteoarthritis.

Arthrocentesis – Also called joint fluid aspiration, arthrocentesis is removal of joint fluid through a hollow needle inserted into the joint space of the knee. Although the purpose of removing joint fluid from the knee is usually so that it can be tested in the lab, removing excess fluid can also quickly ease pain and swelling. Often after withdrawing fluid, doctors use the same puncture site where the fluid was removed to inject a corticosteroid preparation and/or anesthetic into the knee joint to further relieve pain and inflammation.