Arthritis-affected joints are often treated by injecting fluid into them. Depending on the symptoms, injections may include cortisone, hyaluronic acid (viscosupplementation), and PRP injections.

But there's also a treatment option that involves taking fluid out of the joint. This method is known as joint aspiration or arthrocentesis.

Joint aspiration involves taking fluid out of a joint, sometimes for diagnostic purposes.
What Is Arthrocentesis (Joint Aspiration)?

Joint aspiration involves using a needle to extract synovial fluid from either the joint itself or from a protective sac covering the joint called the bursa.

There are 3 reasons joint aspiration may be recommended for someone with arthritis:

  1. To test the synovial fluid for diagnostic purposes

    If your doctor is not sure what exactly is causing your joint pain, the appearance of the synovial fluid and/or a lab test can help him or her reach a definitive diagnosis. For example, the presence of uric acid in the fluid can indicate gout, or a high count of white blood cells can point to rheumatoid arthritis.

  2. ee Diagnosis through Synovial Fluid Analysis

  3. To relieve pressure caused by excess fluid
    Inflammation from arthritis can cause swelling in the joint, which can cause pain and stiffness. Removing some of the joint fluid can ease this inflammation.
  4. To make space for an injectable medication

    Your doctor may want to extract some of your joint's fluid before injecting another substance, such as cortisone or hyaluronic acid.


If your doctor wants you to have a joint aspiration, don't worry. The procedure is often quick (it may take just 10 minutes during a normal office visit) and safe.

See The Joint Aspiration Procedure

Joint aspirations are most often done on the knee joint, but can also be used on the hip, elbow, wrist, or big toe joints. However, a hip joint aspiration is more complicated because of the difficulty in accessing the joint, so it may require an outpatient hospital visit, use of anesthetic, and/or use of ultrasound to guide the needle.

See Arthrocentesis Recovery and Potential Risks

Learn more:

What Is a Synovial Joint?

What Is Bursitis?