What is knee joint aspiration and injection?

Joint aspiration and injection refer to the placement of a needle into a joint cavity to remove fluid for analysis or study, and to inject medicine for pain relief or treatment of a disease (rheumatoid arthritis, gout, pseudogout, infectious arthritis). Sometimes the doctor may only remove some of the joint fluid to establish a diagnosis (or cause) for the collection of fluid. In other cases, such as in patients with chronic osteoarthritis, the doctor may only inject medicine to provide pain relief.

How is the procedure performed?

Your doctor will wash the skin over the joint with an antibacterial solution and then select the easiest and safest method of entry into the joint. Although the skin over the joint can be numbed, the injection of the numbing medicine often hurts more than the needle insertion itself. The needle is inserted carefully into the joint, and fluid may be withdrawn. Without having to perform an additional needle-stick, the syringe holding the fluid can be removed, and a syringe containing the medicine is placed on the needle. The medicine is inserted quickly, and the needle is removed.

Are there risks with needle aspiration and injection?

The risks of this procedure are few. Introducing infection into the joint is uncommon, occurring in less than 0.01 percent of patients. Rarely, the needle tip may damage the cartilage surface inside the joint. The greatest risk of injury to the joint appears to be associated with placing too much medicine in the joint or administering the medicine too often.

Is the procedure painful?

No. Most people find the procedure tolerable. However, the procedure can hurt if the needle touches the joint surface. Your doctor will try to avoid these surfaces, but sometimes this cannot be prevented. If you feel discomfort, it will generally be brief. This procedure is most commonly performed without an anesthetic (numbing medicine). Pain occurring hours after an injection into a joint can develop from the crystals of medicine that are inserted and may be prevented by taking an anti-inflammatory medicine such as ibuprofen (brand names: Advil, Motrin, Nuprin).

If I had a large amount of fluid removed from the joint, can it come back?

Yes. A collection of fluid within the joint is called an effusion. It is common for an effusion to recur after removal of a large amount of fluid. Some experts recommend that an elastic (ACE) wrap be placed over the joint after removal of large amounts of fluid.

If medicine is injected, how long will it be effective?

The response to medicine injected into the joint is variable. Some people get lasting relief, whereas others may only notice improvement for days to weeks. Call your doctor if the pain returns quickly.

Following Joint Aspiration and Injection

1. A bandage was placed over the needle insertion site. You can remove it at any time.

2. One complication of a joint injection is postinjection flare. This is a rare inflammatory reaction to the medicine placed in the joint. The reaction produces intense pain, beginning about 6 to 12 hours after the injection. Patients usually complain that their pain is worse than it was before the injection was performed. To blunt or eliminate this reaction, take ibuprofen, three 200-mg tablets three times a day, for at least the first two days after the injection.

3. If a large amount of fluid was removed from the joint, you may be asked to wear an elastic (ACE) wrap over the site. The wrap is applied to create support and pressure that may reduce the tendency for the fluid to come back. Do not wrap the ACE wrap so tightly that the extremity becomes numb or looks blue.

4. If laboratory studies were performed on the joint fluid, the results should come back in the next few days. Your doctor's office will contact you with the results. Please keep your scheduled follow-up appointment with your doctor.

5. Infection in the joint is uncommon after joint aspiration and injection. If the joint becomes red, warm, or tender, or if you develop a fever in the first few days after the procedure, please call your doctor.

6. If your joint was injected with medicine and local anesthetic, it may be numb for several hours after the procedure. Avoid heavy exercise or placing excessive strain on the injected joint (e.g., carrying children or heavy objects) for the first two weeks after the procedure. Jumping up and down, for instance, can place a heavy load on an anesthetized knee and should be avoided.

7. Joint pain may slowly return after an injection. Some people receive long-term pain relief, but for most people the pain gradually returns. Continue your long-term medicine for the joint as prescribed by your doctor.