A popliteal (Baker’s) cyst is swelling of the fluid-filled sac found in the back of your knee. It usually forms between parts of two muscles that meet at the knee: the gastrocnemius (calf muscle) and the semimembranosus (one of the hamstring muscles). Popliteal cysts are benign, meaning they are not dangerous. Most of the time, a Baker’s cyst in a child will resolve on its own without treatment within 1-2 years. These cysts are usually bigger when the knee is straight and smaller when the knee is bent. The cyst size may change from day to day.

What Causes a Poplieal Cyst? 

In children, Baker’s cyst are usually found in kids between 4-7 years old. These cysts can form in healthy knees and generally do not bother the child or limit their activity. Some children feel a tightness or pressure behind their knee.

How is a Poplieal Cyst Diagnosed?

Your health care provider usually will diagnosis a Baker’s cyst with physical examination. Imaging like x-rays, ultrasounds, MRI or CT scan is generally not necessary to diagnose a Baker’s cyst.

How is a Poplieal Cyst Treated?

You may use a compression sleeve, ice or overthe-counter pain medication for any discomfort. You may continue to participate in all activities if comfortable.

When Should I Seek Further Treatement?

Contact your health care provider if the Baker’s cyst is still present in 1-2 years or if your child develops worsening pain, a large increase in cyst size, redness, fevers, pain in other joints or if they are not participating in their normal activities.

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