Your health care provider is likely to start with a detailed history and physical examination. After that you likely will need tests to find out what's causing your swollen knee.

Imaging tests

Imaging tests can help show where the problem is located. Options include:

  • X-ray. An X-ray can rule out broken or dislocated bones and determine if you have arthritis.
  • Ultrasound. This test uses sound waves to check for disorders affecting the tendons or ligaments.
  • MRI. Using radio waves and a strong magnetic field, MRI can detect tendon, ligament and other soft tissue injuries that aren't visible on X-rays.

Joint aspiration (arthrocentesis)

A needle is used to remove fluid from inside your knee. This fluid is then checked for the presence of:

  • Blood, which may stem from injuries or bleeding disorders
  • Bacteria that may be causing an infection
  • Crystals common to gout or pseudogout


Treatment varies depending on the cause of the swollen knee, its severity and your medical history.


Physical therapy exercises can improve your knee's function and strength. In some situations, a knee brace may be helpful.

Surgical and other procedures

Treating the underlying cause of a swollen knee might require:

  • Arthrocentesis. Removing fluid from the knee can help relieve pressure on the joint. After removing some of the joint fluid, your doctor might inject a corticosteroid into the joint to treat inflammation.
  • Arthroscopy. A lighted tube (arthroscope) is inserted through a small incision into your knee joint. Tools attached to the arthroscope can remove loose tissue or repair damage in your knee.

Self care

Taking care of yourself when you have a swollen knee includes:

  • Rest. Avoid weight-bearing activities as much as possible.
  • Ice and elevation. To control pain and swelling, apply ice to your knee for 15 to 20 minutes every 2 to 4 hours. When you ice your knee, be sure to raise your knee higher than the level of your heart. Place pillows under your knee for comfort.
  • Compression. Wrapping your knee with an elastic bandage can help control the swelling.
  • Pain relievers. Over-the-counter medicines such as acetaminophen (Tylenol, others) or ibuprofen (Advil, Motrin IB, others) can help reduce your knee pain.

Preparing for your appointment

You may be referred to a health care provider who specializes in musculoskeletal and joint problems.

What you can do

  • Write down your symptoms, and when they began.
  • Write down your key medical information, including other conditions.
  • Write down key personal information, including any major changes or stressors in your life.
  • Make a list of all your medications, vitamins or supplements.
  • Find out if anyone in your family has had an autoimmune disease.
  • Ask a relative or friend to accompany you, to help you remember what the health care provider says.
  • Write down questions to ask the provider.

Questions to ask your doctor

  • What's the most likely cause of my symptoms?
  • What kinds of tests do I need?
  • What treatments are available?
  • I have other health conditions. How can I best manage them together?

What to expect from your doctor

Your health care provider is likely to ask you a number of questions. Being ready to answer them may leave time to go over points you want to discuss in depth. You may be asked:

  • Have you injured your knee recently? If so, describe the injury in detail.
  • Does your knee "lock" or feel unstable?
  • Has your knee felt warm or looked red? Do you have a fever?
  • Do you play recreational sports? If so, what sports?
  • Do you have any type of arthritis?
  • Do you have a family history of autoimmune disease?

Jun 16, 2022

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  2. Firestein GS, et al. Hip and knee pain. In: Firestein & Kelley's Textbook of Rheumatology. 11th ed. Elsevier; 2021. https://www.clinicalkey.com. Accessed April 12, 2022.
  3. Beutler A, et al. Physical examination of the knee. https://www.uptodate.com/contents/search. Accessed April 12, 2022.
  4. Evaluation of the knee. Merck Manual Professional Version. https://www.merckmanuals.com/professional/musculoskeletal-and-connective-tissue-disorders/approach-to-the-patient-with-joint-symptoms/evaluation-of-the-knee?query=knee%20effusion. Accessed April 12, 2022.
  5. Roberts WN. Joint aspiration or injection in adults: Technique and indications. https://www.uptodate.com/contents/search. Accessed April 12, 2022.
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