A Baker's cyst is a pocket of fluid that forms a lump behind the knee.
It is also called a popliteal cyst. See a picture of a
A Baker's cyst is caused when excess joint fluid is pushed into one of the small sacs of tissue behind the knee. When this sac fills with fluid and bulges out, it is called a cyst. The excess fluid is usually caused by conditions such as rheumatoid arthritis or osteoarthritis that irritate the knee. It may also be caused by an injury.
Baker's cyst causes no pain. When symptoms occur, they may include:
Sometimes the pocket of fluid behind the knee can tear open
and drain into the tissues of the lower leg. This can cause swelling and
redness in that part of the leg.
Your doctor will examine your knee and ask
you questions about your past health and when the pain and swelling started.
Your doctor may order tests, such
MRI, to see a picture of the inside of your knee.
A Baker's cyst may go away on its own.
If arthritis or another problem is causing the Baker's cyst, your doctor
may treat that problem. This usually makes the pain and swelling of a Baker's
cyst go away.
If a cyst does not go away, or if it is causing a
lot of pain, your doctor may drain the fluid with a needle. You also may be
given a shot of
steroid medicine to reduce swelling. You may need to
use a cane or crutch and wrap your knee in an elastic bandage. In rare cases, a
Baker's cyst is removed by surgery.
There are things you can do
at home to help you feel better.
Other Works Consulted
American Academy of Orthopaedic Surgeons and American Academy of Pediatrics (2010). Popliteal cyst. In JF Sarwark, ed., Essentials of Musculoskeletal Care, 4th ed., pp. 716–718. Rosemont, IL: American Academy of Orthopaedic Surgeons.
Hanada E, et al. (2008). Baker's cyst. In WR Frontera et al., eds., Essentials of Physical Medicine and Rehabilitation: Musculoskeletal Disorders, Pain, and Rehabilitation, 2nd ed., pp. 315–317. Philadelphia: Saunders Elsevier.
August 7, 2012
William H. Blahd, Jr., MD, FACEP - Emergency Medicine
& Kenneth J. Koval, MD - Orthopedic Surgery, Orthopedic Trauma
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