Diagnosis Popliteal cysts cause pain behind the knee that at times radiates into the back of the leg. Swelling that goes up and down is characteristic of a popliteal cyst. Difficulty or pain with fully straightening the knee can also be seen. The diagnosis is made by a careful history and physical by your doctor. X-rays may be taken to evaluate the joint and occasionally ultrasound or an MRI is ordered to confirm the diagnosis.
Treatment begins with rest, short term immobilization of the joint and anti-inflammatory medication.
An elastic wrap coupled with icing may reduce the size of the popliteal cyst and the severity of the symptoms. Draining the cyst with a needle and instilling steroids in the cyst cavity may be indicated if the initially treatment regimen fails. Isolating the cause of the cyst and eliminating it is the goal of surgery. This can usually be done arthroscopically if the cause is inside the knee. Rarely, open removal of the cyst and its lining is needed to effect a cure.