What is a baker's cyst?
A cyst is a sac that usually contains one of three types of matter: gas, fluid or semi-solid material. Having a cyst appear can alarm you if you aren't sure what it is. The good news is that most cysts are of a benign nature. A baker's cyst (also known as a popliteal cyst) is the development of a soft, fluid filled sac located on the back of the knee. Baker's cysts occur for different reasons. If a Baker's cyst ruptures, it can be very painful.
Why does a baker's cyst occur?
The joining of the thighbone and the shinbone forms the knee joint. The joint capsule encloses the joint. The joint capsule is lined with the synovial membrane. The synovial membrane produces a slippery fluid (synovial fluid), which allows the bones to move over each other without friction. A popliteal cyst forms when the joint lining produces too much joint fluid. The extra fluid fills up the joint capsule and then pushes through the joint lining, forming a cyst. The cyst can often be seen or felt on the back of the knee. The cysts occur most often as a result of an injury, inflammation of the joint lining or another condition such as arthritis or gout.
What are the signs and symptoms of baker's cyst?
Typically, patients complain of one or more of the following:
Pain, especially when moving the knee.
Swelling at the back of the knee.
Tenderness over the affected area.
Aching or pain with exercise.
The knee may give way when exercising.
The cyst may swell with increased activity and shrink with rest.
The cyst may rupture, leaking fluid into the calf area.
How is baker's cyst diagnosed?
Your physician will ask you many questions about the pain in your knee. For
example when it began, did an injury precede the problem, does the pain and
swelling increase with activities, does anything seem to relieve the pain. Many times the diagnosis can be easily made based on the physical exam. Your doctor may or may not take X-rays depending on the rest of the clinical findings. Sometimes a sonogram is ordered to confirm the diagnosis.
How is a baker's cyst treated?
The initial goal is to control pain, reduce inflammation and swelling, and
protect the injured knee.
REST: Rest the knee as much as possible. Avoid activities requiring the
frequent bending and straightening of your knee.
ICE: Use frequent ice massage by filling a cup with water and freezing.
Peel back the paper from the end of the cup, exposing the ice. Massage
firmly over the injured area in a circular fashion. Repeat this for 15
minutes 3 or 4 times per day. Be careful not to over-expose the skin.
ELEVATION: Whenever possible, elevate the knee above the level of the
heart to reduce swelling and prevent the accumulation of fluid in the
affected joint. Use pillows to elevate the foot above the level of the heart.
This position allows gravity to remove the fluid from the knee.
Is medication necessary for a baker's cyst?
Your physician may prescribe an NSAID (non-steroidal anti-inflammatory
medication) such as Advil or ibuprofen to help reduce the pain and inflammation.
In some cases, the cyst may be aspirated and then injected with a long lasting
local anesthetic mixed with a corticosteroid drug. There must be no sign of
infection if a steroid is used. Follow the instructions of your physician
regarding the amount and frequency of any medication.
Is surgery necessary for a baker's cyst?
Most of the time, a baker's cyst is treated non-surgically. However, it is
important to treat the underlying cause of a baker's cyst, otherwise the
cyst may recur. If the cyst is extremely painful or interferes with the
normal use of your knee, then surgery may be recommended. If surgery
is needed, it is usually done on an out patient basis. Unless there is a lot
of discomfort from the cyst, surgery is rarely indicated.
The goal of rehabilitation is to return to your sport, work or activity as soon as
medically possible. Everyone, especially athletes, is anxious to return to activity.
Returning to soon can cause more damage. Follow your physician's advice
regarding your activity level and date of return. Length of recovery will vary from
person to person.