FAMILY MEDICINE® COLUMN

By John C. Wolf, D.O.Associate Professor of Family Medicine Ohio University College of Osteopathic Medicine

KNEE PAIN FROM BAKER'S CYST MAY REQUIRE SURGERY

Question: I recently had an MRI of my knee that showed a Baker's cyst along with a cartilage problem. I had arthroscopic surgery for the torn cartilage. My surgeon said that I shouldn't worry about the Baker's cyst unless it caused me pain, which it didn't at the time. Now that I am walking 1 1/2 miles every day, my knee hurts. My surgeon says that operating on the cyst is not in his expertise. Who should I see to get help for my Baker's cyst?

Answer: First, I need to give the other readers of the Family Medicine® column a little background on Baker's cyst. Despite what you might first think upon hearing the name, it's not an occupational hazard of those who practice the trade of baking. Instead, it's a cyst in the tissue behind the knee that was first described in the medical literature in 1877 by Dr. William Morrant Baker, a British surgeon.

Cysts are abnormal saclike growths. They can arise in many areas of the body in several different types of tissue. As I mentioned, a Baker's cyst develops in tissue behind the knee in an area called the popliteal fossa. Consequently, we doctors also call a Baker's cyst a popliteal cyst. The cyst itself arises from either the lining of the knee joint or from one of the normal structures in this area called bursae. Each of these saclike structures -- located between a tendon and a bone -- contains a thick fluid thats purpose is to lubricate the surfaces where the tendon slides over the bone so as to reduce friction and wear.

Two specific bursae -- Semimembranosus and Gastrocnemius -- are the most common source of popliteal cysts in children. While these and other bursas can also be the source of Baker's cysts in adults, it is more common for these cysts in adults to originate from the lining of the knee joint.

Adults with popliteal cysts have other knee joint problems 50 percent of the time. Your previous cartilage problem puts you into this group. In addition to cartilage problems, cysts are more common in those with rheumatoid arthritis, osteoarthritis or torn ligaments. In these individuals, no treatment of the cyst is likely to be effective unless the co-existing knee disorder is treated, too.

Withdrawing most of the fluid through a large diameter needle and then injecting cortisone back into the cyst sac can treat a Baker's cyst, particularly one that originates from a bursa. Unfortunately, this relatively simple treatment doesn't always work for those with cysts from bursae, and it never works for those with cysts originating from the knee joint itself. Therefore, some orthopedic surgeons don't even bother with this treatment. Instead, they recommend surgical removal of the cyst.

A popliteal cyst is removed by surgically cutting away all of it, including its attachment to the bursa or knee joint. This is usually quite effective. Your orthopedic surgeon is apparently not sufficiently experienced with this type of surgery to be comfortable doing it for you. Therefore, you should ask your family doctor or your orthopedic surgeon for a referral to an orthopedic surgeon with the necessary expertise.

"Family Medicine" is a weekly column.

To submit questions, write to: John C. Wolf, D.O., Ohio University College of Osteopathic Medicine, Grosvenor Hall, Athens, Ohio 45701.

Past columns are available online at http://www.FamilyMedicineNews.org.