Is a Popliteal Cyst?
A popliteal cyst, also known as a Baker’s cyst, is a fluid-filled
swelling that causes a lump at the back of the knee, leading to tightness and
restricted movement. The cyst can be painful when you bend or extend your knee.
Usually, this condition is due to a problem that affects the knee
joint, such as arthritis or a cartilage injury. Treating the underlying cause
can often alleviate the problem. Though a popliteal cyst doesn’t cause any long-term
damage, it can be very uncomfortable.
Are the Causes of a Popliteal Cyst?
Synovial fluid is a clear liquid that normally circulates through
the cavities in your knee joint. Sometimes the knee produces too much of this
fluid. The increasing pressure forces the fluid to the back of the knee, where
it creates a bulge. This severe swelling of the knee causes a popliteal cyst to
The most common causes of a popliteal cyst are:
- damage to the knee’s cartilage (meniscus)
- arthritis of the knee
- rheumatoid arthritis
- other knee conditions that cause joint
Since the knee is a complicated joint, it can be injured easily.
According to the American
Academy of Orthopedic Surgeons (AAOS), about 10.4 million Americans saw
their doctors about a knee problem in 2010, making it the most common reason
for seeing an orthopedic specialist. Such injuries may cause the inflammation
that leads to a popliteal cyst.
A blood clot can also cause bruising and swelling behind the knee
and on the back of the calf. It’s important that your doctor examines the
swelling to determine if the cause is a cyst or a clot. An MRI or ultrasound
might be used to help make a diagnosis.
Are the Symptoms of a Popliteal Cyst?
You may not feel any pain with a popliteal cyst. In some cases,
you may not notice it at all. If you do experience symptoms, they might
- mild to severe pain
- limited range of motion
- swelling behind the knee and calf
- bruising on the knee and calf
- rupturing of the cyst
Is a Popliteal Cyst Diagnosed?
Your doctor will examine your knee and feel the swelling. If the
cyst is small, they may compare the affected knee to the healthy one and check
your range of motion.
Your doctor may recommend more tests if the cyst rapidly
increases in size or causes severe pain or fever. These will determine if some
other form of growth, such as a tumor, is causing the swelling. These
noninvasive tests include MRI and ultrasounds.
Although the cyst won’t show up on an X-ray, your doctor may use
one to check for other problems, such as inflammation or arthritis.
An MRI will enable your doctor to see the cyst clearly and to
determine if you have any damage to the cartilage.
a Popliteal Cyst
A popliteal cyst often doesn’t need treatment and will go away on
its own. However, if the swelling becomes large and causes severe pain, your
doctor may recommend one of the following treatments.
Your doctor will insert a needle into the swelling and use an ultrasound
to help guide the needle to the correct place. They’ll then draw the fluid from
Regular, gentle exercises may help increase your range of motion
and strengthen the muscles around your knee. Crutches may help alleviate the
pain. You can also help reduce pain by using a compression wrap or placing ice
on the joint.
Your doctor may recommend a corticosteroid medication, such as
cortisone, for the cyst. Your doctor will inject this drug into the cyst.
Though it may help relieve the pain, it doesn’t always prevent a popliteal cyst
Treating the cause of the cyst is very important to prevent the
cyst from returning. As a
general rule, if the cyst is left alone it will go away once the underlying
cause is treated. Should your doctor determine that you have damage to
the cartilage, they may recommend surgery to repair or remove it.
If you have arthritis, the cyst may persist even after your
doctor treats the underlying cause. If the cyst causes you pain and limits your
range of motion, your doctor may recommend surgery to remove it.
Associated with Popliteal Cysts
Complications are rare, but they may include:
- prolonged swelling
- severe pain
- complications from related injuries, such as
Is the Long-Term Outlook for a Popliteal Cyst?
A popliteal cyst won’t cause any long-term damage, but it can be
uncomfortable and annoying. The symptoms may come and go. In most cases, the
condition will improve over time or with surgery. Long-term disability due to a
popliteal cyst is very rare.