No, bakers, this has nothing to do with you. It is named after the surgeon, Dr. William Morrant Baker, who first described it.
If you feel a bulge behind your knee, and it feels tight in the area, with pain getting worse when you fully extend (stretch out) your knee, or when you’re active, you could have a Baker’s cyst, also called a popliteal cyst. It is usually the result of a problem with your knee joint, such as arthritis or a cartilage (meniscus) tear. In both cases, too much fluid can be produced, leading to the cyst. Treating the probable underlying condition usually relieves the swelling and discomfort of the cyst.
They’re more common between ages 55 and 70, and between 4 and 7. Up to 20% of people with other knee problems may develop one though.
SIGNS AND SYMPTOMS
Sometimes, a cyst causes no pain and goes unnoticed. At times you may get:
• Swelling behind your knee, and sometimes in your leg or foot.
• Knee pain.
• Tightness in the back of your knee.
WHAT CAUSES IT?
Just as a door hinge needs oil (and sometimes WD-40) to swing smoothly to reduce friction between its moving parts and minimize wear and tear, so it is that the cartilage and tendons in your knees rely on a lubricating fluid called synovial fluid. This helps your legs swing smoothly and reduce friction between your knee’s moving parts.
Synovial fluid circulates throughout your knee and passes in and out of various tissue pouches (bursae) throughout your knee. A valve-like system between your knee joint and the bursae on the back of your knee (popliteal bursa) regulates the amounts of synovial fluid going in and out of the bursa.
But sometimes, most commonly as a result of inflammation of the knee joint, the knee produces too much synovial fluid. Various types of arthritis and knee injury, such as a cartilage tear, may be the culprit.
When the popliteal bursa fills with fluid and expands, the result is a bulge called, you guessed it, a Baker’s cyst. It is similar to a balloon filled with water.
SEEK MEDICAL ADVICE
If you’re having pain and swelling behind your knee, check doc to find out the cause. Treating the underlying problem, such as arthritis or a cartilage tear, usually relieves the discomfort of a Baker’s cyst. Rarely, a bulge in that location could be a tumor or an aneurysm (a weakness in the blood vessel wall) of the popliteal artery, rather than a cyst.
SCREENING AND DIAGNOSIS
How can we tell whether you have a Baker’s cyst? An ultra sound scan or an MRI can help distinguish a simple cyst. If a DVT or an aneurysm is suspected, a Doppler ultra sound scan of your leg or other tests may be requested.
Uncommonly, a Baker’s cyst bursts and synovial fluid leaks into the calf region, causing sharp knee pain, swelling, and sometimes redness in the calf. These signs and symptoms are similar to a blood clot (DVT) in your leg. Redness and swelling of your calf requires prompt medical evaluation; you know well that a blood clot may require urgent treatment because of the possible complications.
TREATMENT OF A BAKER’S CYST
If the cyst is very large and causes a lot of pain, the doctor may use the following treatments:
• Physical therapy. Icing, a compression wrap, and crutches help keep pain and swelling down. Gentle range of motion and strengthening exercises for the muscles around your knee may also reduce your symptoms and preserve knee function.
• Fluid drainage. Doctor may drain the fluid from the knee joint with a needle. This is called needle aspiration.
• Medication. Doctor may inject a corticosteroid medication, such as cortisone, into your knee to decrease the volume of fluid being produced. Pain may be relieved but it doesn’t always prevent recurrence of the cyst.
The best thing, which is what doctors try to do, where possible, is to treat the underlying cause rather than the Baker’s cyst itself.
If it’s a cartilage tear causing the overproduction of synovial fluid, doctor may recommend surgery to remove or repair the torn cartilage.
Sometimes, especially if you have osteoarthritis, the cyst may remain even after the underlying cause is treated. If the cyst doesn’t get better, causes pain and interferes with your ability to bend your knee, or if – despite aspirations – fluid in the cyst hinders knee function, you may need to be evaluated for surgery to remove the cyst.
Baker’s cysts in children nearly always disappears with time, and rarely require excision.
ARE THERE SELF-CARE ANSWERS?
If arthritis is determined to be causing the cyst, doctor may advise you to take some or all of the following steps to reduce inflammation and lessen synovial fluid production.
• Try nonsteroidal anti-inflammatory drugs (NSAID’s) or acetaminophen. NSAID’s are aspirin, ibuprofen, naproxen, diclofenac, indomethacin and others. Acetaminophen is Tylenol, paracetamol is similar. Prescription, rather than over-the-counter strengths, are preferable.
• Follow the P.R.I.C.E. principles. This is an acronym for protection, rest, ice, compression, and elevation. Protect by using crutches to keep weight off the knee and allow pain-free walking. Rest your leg. Ice the inflamed area. Compress your knee with a wrap. And elevate your leg, especially at night.
• Scale back your physical activity. This will reduce irritation of your knee joint.
See you next week.
Dr. Emanuel, based in the Commonwealth of Dominica, has been an educator of medical professionals, in training and the public, for over 20 years.