Knee > Synovitis

What is Synovitis?

A protective membrane, called synovium, covers all the bones, tendons, and cartilage in your knee. The membrane surrounds a thick fluid, called synovial fluid, which lubricates your knee and helps it move smoothly. Synovitis occurs when the protective membrane becomes irritated or inflamed. Your knee swells as the synovium produces too much fluid.

Traumatic and repeated injuries commonly cause synovitis. It usually accompanies an underlying joint injury that has chipped or roughened any of the surfaces in your knee. Joint diseases, especially rheumatoid arthritis and gout, can also cause synovitis. You are most at risk of suffering synovitis in contact sports like football. The risk of synovitis also increases after repeated knee injuries of any kind.

Synovitis usually does not put you at risk of any dangerous complications, and physicians generally suggest healing with ice and anti-inflammatory medication. If pain and swelling do not go away, further treatment may be necessary.

There usually are three parts to an orthopedic evaluation: medical history, a physical examination, and tests that your physician may order.

Your physician will likely ask you when you noticed the swelling, how much pain you have been feeling, and if your knee has been previously injured. Physicians also typically ask about other conditions, such as diabetes and allergies, and medications currently being taken. Your physician may also ask about your physical and athletic goals, information that will help determine what treatment might be best for you in achieving those goals.

The key to diagnosing synovitis is finding the underlying cause. While asking you questions to pinpoint your pain, physicians will also test ligament and tendon strength by checking your knee's range of motion. Depending on what your physician suspects is causing synovitis, you may undergo a more thorough physical exam to diagnose arthritis, meniscus tears, cartilage damage, or other knee problems.

TESTS

Should your physician require a closer look, MRI (magnetic resonance imaging) is generally the best method for obtaining a clear picture of synovitis. MRI can sometimes be used to catch minor synovitis before the swelling becomes painful and visible to the eye. If your physician suspects synovitis, some of the fluid will usually be removed from your knee. Using a needle, your physician can quickly remove a fluid sample and have it tested in the laboratory. Synovial fluid that is infected by synovitis has unique characteristics that can be tested to make the final diagnosis. Arthroscopy, a surgical procedure that uses an arthroscope, an instrument which allows a surgeon to see inside the knee joint, is sometimes used as a final diagnostic tool. Arthroscopy can also be used to clean out the inflamed synovium. Depending on other knee problems associated with synovitis, your physician may order appropriate tests to make a separate diagnosis.

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