FAMILY MEDICINE® COLUMN

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

BAKER'S CYST MAY HEAL ITSELF OR REQUIRE SURGERY, TIME WILL TELL

Question: My doctor told me my knee pain is from a Baker’s cyst. What is this and what can be done for it besides the “waiting and watching” he suggested?

Answer: The knee joint is subjected to substantial forces. When standing still each one supports about one-half the body’s weight. When running is the method of travel, the body weight is alternatively supported by one leg then by the other, but because of the forces involved in acceleration and deceleration while running, the knee can actually be stressed by several times the weight of the body. All this is to dramatize the typical robust nature of the knee joint.

Because of the forces it must endure, it is not surprising that knee problems are common, and many of these disorders cause pain. A Baker’s cyst typically causes pain behind the knee in the area we doctors call the “popliteal space.” In addition to pain, there is usually a bump or swelling that can be felt where none previously existed. Typically this is behind the knee on the medial side -- the surface that’s nearer to the other leg. The pain of a Baker’s cyst can start suddenly, although most of my patients have had the discomfort for weeks before they finally come in to be examined.

The knee, like most joints, has a lining that produces fluid to help nourish and lubricate the joint. This lining --the synovium or synovial membrane -- produces lubricating fluid with the unimaginative name of “synovial fluid.” Under some conditions the synovial membrane pushes through the tough supporting joint capsule and forms a balloon like sack. This sack is the Baker’s cyst, and it is filled with synovial fluid.

A Baker’s cyst usually occurs because of some other underlying knee problem. Determining the nature of that primary disorder requires a “hands on” examination of the knee. Your doctor will then ask you to carefully retell the saga of your knee problem. This will include answering such questions such as: How did your knee pain begin? What makes it better? What makes it worse? And, how it has the problem changed since it first began?

Often, some type of imaging technology is needed before a final diagnosis can be reached. This can include one or more of the following: an X-ray, ultrasound or MRI. The most common disorders that cause a Baker’s cyst -- osteoarthritis and rheumatoid disease -- can often be discovered through this imaging process. A torn meniscus or other knee disorders can also produce a Baker’s cyst.

Removing the fluid from a Baker’s cyst with a syringe is often sufficient treatment. This deflates it and, thereby, reduces the pain. Unfortunately, more synovial fluid can be produced to refill the cyst, although this doesn’t always happen. In fact, cysts sometimes rupture on their own and “go away” without any treatment. This is what your doctor is hoping will happen to you.

A Baker’s cyst that is causing pain and refills after being drained may need to be surgically removed. The orthopedic surgeon, while roaming about inside your knee, will also use surgical techniques to address the underling knee problems such as knee instability or a torn meniscus. This approach is often quite successful. Unfortunately, though, the majority of sufferers who have arthritis as the underlying problem don’t get lasting improvement from surgical treatment because the underlying arthritis condition continues unabated.

Talk to your family doctor again if your cyst doesn’t resolve itself in a reasonable period of time. At that point, I’d recommend asking for a consultation with an orthopedic surgeon to determine the best treatment for your Baker’s cyst.

"Family Medicine" is a weekly column. To submit questions, write to John C. Wolf, D.O., Ohio University College of Osteopathic Medicine, P.O. Box 110, Athens, Ohio 45701. Past columns are available online at http://www.FamilyMedicineNews.org.