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Persistent Knee Swelling

Good. These might seem like strange questions to ask, but again, there is a good reason for them!

It turns out that about 10-20 percent of people with psoriasis or colitis also have a form of arthritis that commonly affects the knee. And if you have multiple other joints that are persistently painful and swollen, rheumatoid arthritis is a real possibility. Joint symptoms tend to be much worse in the morning. Arthritis due to a viral infection can mimic rheumatoid arthritis except that it tends to go away within 3-6 weeks (and often sooner).

Your answers argue against the diagnosis of psoriatic arthritis, colitis-associated arthritis or rheumatoid arthritis, but sometimes knee arthritis comes before the other typical features. Over time, one of these diagnoses could be reconsidered as a possible cause of your knee swelling.

Sometimes, despite a thorough review of the circumstances surrounding your knee swelling, a full examination, and, perhaps routine x-rays, the cause of your swelling may not be clear. If it persists and is associated with significant symptoms (pain, instability, or locking, for example), your doctor may recommend one or more of the following tests:

apping the joint for synovial fluid analysis - after numbing the skin, a needle is inserted into the knee and joint fluid is removed; the fluid is sent to the laboratory for analysis, including the number and type of white cells (measures of inflammation), tests for infection (called gram stain and culture) and inspection under a special microscopic looking for crystals (as seen in gout or pseudogout).

  • MRI - a large magnet is used to create pictures of the inside of the knee, including bones, cartilage, ligaments and tendons

  • CT scan - a specialized series of x-rays that create a three-dimensional picture of the knee

  • arthroscopy - a tube with a light and camera on the end, roughly the size of a pencil, is inserted into the knee to directly view the interior of the joint; certain abnormalities, such as damaged cartilage or a loose bone fragment, can be repaired with this instrument.

Regardless of whether any of the conditions reviewed in this guide seem to fit your situation, contact your doctor for evaluation and follow-up. Even if the cause is uncertain now, a diagnosis may be much clearer over time.

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