Just what is it?
It is a cyst, or fluid filled sack, that swells up behind the knee. The cyst, also known as a popliteal cyst, can cause pain if you either bend or straighten the knee when doing activities. Some cysts cause a visible swelling behind the knee.
The discomfort may get worse after standing for a long time or after exercise.
Getting a bit more technical.
You have a capsule around your knee with a lubricating fluid in it called synovial fluid. This allows your leg to swing smoothly by reducing friction between the Femur and Tibia. At times it is possible for the knee to produce too much fluid resulting in a fluid build-up behind the knee in the popliteal bursa. This condition was first discovered by Dr Baker, hence its name.
What causes it?
This is an inflammatory response and can happen as a result of arthritis or a cartilage tear.
It is possible for the cyst to rupture, and for the fluid to leak into the calf. This might show up as redness in the calf area. Some people report that they felt as if water was running down their calf. (Did I hear an ‘ewwww’?)
What do you do if you think you have one or if you have redness on the back of your calf?
Make an appointment with your GP. It is important that the injury is properly researched and that you work out why you have it.
Redness on the calf can also mean that you have a DVT or deep vein thrombosis. This needs to be treated as a medical emergency.
Assuming it is not a DVT, the diagnosis and treatment of which is beyond the scope of this blog, your doctor may do one of the following-
Inject a corticosteroid medication, such as cortisone, into the knee to reduce inflammation. This will reduce inflammation but it is not a cure.
Your doctor might aspirate the sack. In this procedure the fluid is drained from the sack by way of syringe and needle.
Your doctor might advise a compression bandage and ice to reduce pain and swelling.
Over and above these things it is important that the underlying cause is found. As said before, this could be as a result of cartilage damage or arthritis. In extreme cases surgery to remove the cyst is advised. This only happens when the sack fills up repeatedly.
Hopefully, this is an condition that you will never have, and if you do, that you will recover quickly.