What Causes Baker's Cyst?
Baker's cyst
Detailed Answer:
Hello and thanks for your question.
It sounds like you may have developed a Baker's cyst. I suggest that you wear an ace bandage on it, continue to ice it and prop it up whenever possible. If the pain goes away then it is probably this type of cyst, though the swelling may persist for some time.
If you have any weakness in your leg or locking of the knee then you may have damaged a tendon or the meniscus (cartilage of the knee) and in that case you may need an MRI to determine what exactly is going on.
Definitely if the pain worsens, the swelling increases or you develop new leg symptoms then an MRI would be indicated.
I have had many patients with Baker's cysts. They feel like a small or sometimes large ball behind the knee. Mostly they resolve on their own but it can take time. The fact that this happened after prolonged sitting cross legged and that there was no trauma involved a good sign that no serious damage has probably occurred to your knee.
I hope it is better soon,
K. Robinson MD
it can
Detailed Answer:
Sometimes they do drain a Baker's cyst if it is very large, but usually they don't because they tend to reaccumulate. Sometimes they will give a steroid shot into the knee. Often though they go away on their own without any treatment. Here is a link for you to read more about the condition and see if you think that is what you have.
http://www.uptodate.com/contents/bakers-popliteal-cyst-the-basics?source=search_result&search=bakers+cyst&selectedTitle=1~25
I hope you get some relief soon
K. Robinson MD