There are two main treatment options for popliteal cysts of the knee: the first is conservative treatment. A popliteal cyst in the knee can be treated conservatively by using a syringe under ultrasound guidance to extract the contents of the popliteal cyst as cleanly as possible, then injecting an appropriate amount of tretinoin injection into the local swelling, and then applying an appropriate pressure bandage. This can promote adhesion of the cyst so that it does not recur, but the success rate of this treatment is not 100% and there is a greater chance of recurrence. The second type of treatment is surgery. If conservative treatment does not work or if the cyst seriously affects life, surgery can be considered to remove it completely.