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Dr. Allan Mishra | Knee Pain Diagnosis


(Bakerís Cyst)

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Definition An abnormal sac filled with fluid found in the back of the knee or leg
Details Popliteal (Baker's) cysts are common and at times may be confused with a clot in the leg. If they become large enough they may even lead to compression of the major vein coming from the leg.

Picture of a large cyst
Causes Popliteal cysts can arise from irritation of a bursa (a normal fluid filled sac that lubricates two surfaces) that exists between two muscle behind the knee. These cysts may also be caused by cartilage tears or arthritis within the knee.
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.

MRI of a Popliteal Cyst
Treatment Nonoperative: 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.

Picture of draining the cyst
  Operative: When non-operative measures have been exhausted, operative intervention is warranted. 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.

Not much can be done to prevent a popliteal cyst other than avoiding injury to the knee by maintaining its strength and stability.