What's Behind Your Behind-Your-Knee Pain?

Updated March 28, 2022
Overview

Just as car oil lubricates the components of an engine, our knee is lubricated by fluid that allows the joint to bend and move easily. Injury or illness can disrupt this lubrication system and cause too much joint fluid to be pumped into a small sac behind the knee. Known as a Baker’s cyst, this lump is often mistaken for something more serious.

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“Most often we see Baker’s cysts when a doctor has suspected a blood clot and orders an ultrasound,” says Jeff Bytomski, DO, a sports medicine specialist with Duke Orthopaedics. “The radiologist reads the scan and discovers a Baker’s cyst instead.” Treating the cyst is not important if there are no symptoms and they rarely cause further problems. Most of the time we tell patients not to worry about it,” he says.

In some cases, however, this buildup of fluid may occur along with a problem in the knee joint and can cause pain and stiffness “If it’s causing pain, it’s most likely due to previous damage, such as arthritis, a torn meniscus, or other damage to the joint,” says Dr. Bytomski. “In these cases, we try to treat the initial injury or illness rather than focusing on the cyst itself.”

How to Treat Baker's Cyst

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Although it’s not typically necessary, draining the cyst or treating it with surgery is sometimes required, he notes. Baker’s cysts can usually be treated by resting the knee, applying ice packs, and taking NSAID pain relievers such as aspirin, ibuprofen, or naproxen. If the pain is particularly bad, your doctor may suggest a joint injection to treat the underlying illness or injury.

As with most joint injuries, athletes are at higher risk of developing this cyst because of the strain they put on their knees. If you are doing a lot of exercise, you can protect yourself from developing a Baker’s cyst by wearing proper shoes when exercising, warming up and cooling down, and taking care to rest the knee if it is injured in any way.