Treatment of Edema

I injured my knee recently. Its been about 3 weeks and while the knee feels completely fine, I have a build up of fluid under my skin to the right of my kneecap. Is this something that goes away naturally? Is there any hazard to leaving the fluid there?

There are two possibilities that could possibly explain the swelling of fluid in your knee cap – an edema or a meniscal cyst. An edema is condition in which a fluid called interstitial fluid accumulates in the surrounding tissue. This fluid in the tissue is not something that is entirely abnormal because interstitial fluid is formed as the regular blood pressure forces out fluid from the blood in sieve like mechanism into the tissue. This fluid that accumulates in the tissues is then pushed into the lymphatic system and is filtered and screen and the lymph nodes all over the body. When we get injured, an edema or swelling of interstitial fluid can occur normally. Not to mention, inflammation itself that can cause the tissue to swell up. This is almost always accompanied by pain and since you have specifically mentioned no pain, the pall of suspicion falls on a cyst.

A cyst is sometimes caused by trauma or injury and the healing of the affected part of the body can be a bit askew. An accumulation of fluid which is then covered by a sac sometimes occurs causing a cyst. Many fluid filled cysts are caused due to trauma near a zone where there is already some fluid around, as is the case in a ganglion cyst of the joints when synovial fluid gets trapped in a sac. In your case, the correct terminology would be a meniscal cyst. This occurs in an area of tissue called the meniscus – a tissue that surrounds the muscles of the knee that is made up of cartilage.

The fluid that is within a meniscal cyst is usually synovial fluid itself. This is because of the proximity of the meniscus to the knee joint itself and any kind of trauma to the joint capsule could leak the lubricating synovial fluid into the meniscus. Treating a meniscal cyst is a matter of repairing the tissue that is damaged along with excision and aspiration of the cyst. Aspiration is a simple surgical procedure in which in incision is made from the surface of the skin to the cyst. A needle and syringe are then used to aspirate the contents of the cyst. An excision may be required to remove the sac of the cyst and also to seal off the supplying root of the cyst as well. Once a cyst occurs, it is very rare that it would occur again.

answered by G M

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