It is a question that comes up quite often at the office and I thought I should give it its own blog entry. A Baker's cyst is almost a common household term but it's often very misunderstood.
Most patients think of a cyst as some sort of standalone lesion. A Baker's cyst is actually more so an outpouching of the synovial capsule of the entire knee joint. It is a non-specific finding associated with a variety of mechanical problems with the knee joint: aggravated osteoarthritis, recent sprain, meniscal tear, severe misalignment. All of these will cause some increased fluid production in the joint which will escape in the weakest part of the joint capsule, which happens to be in the back of the knee. Think of it as the "storm pond" of the knee. In some people the outpouching from the increased fluid pressure will result in a distinct round mass that often will extend downward into the upper portion of the posterior calf. It will prevent comfortable flexing of the knee especially.
In addition to the more traditional compression and icing recommendations, sometimes needle draining the Baker's cyst will be performed to relieve an acute situation. It will bring about some much welcome temporary relief, but that will be short-lived. The reason is that a Baker's cyst is caused by something else. It will recur at a high incidence if the reason for the cyst is not recognized and addressed.
In our chiropractic practices, we have found that a Baker's cyst highlights the need to look more closely at what's going on in the knee, and the entire lower extremity. Intrinsic subluxations of the knees, especially misalignment of the lateral tibia posterior, is excessively common especially with osteoarthritis of the lateral compartment of the knee. Something as simple as a posterior adjustment of the tibia can make a big difference in the amount of pressure building up in the posterior knee joint. However we also need to zoom out and look at the bigger picture, looking at the alignment of the lumbar spine, pelvis, foot and ankle, as to how much it's loading up the knee incorrectly, and address that as well.
The bottom line: a posterior swelling in the back of the knee is often categorized as a Baker's cyst, but you need to understand that this nomenclature refers to the end result of a variety of mechanical, postural, muscular imbalance, and alignment issues associated with the entire pelvis and lower extremity that are best understood and treated together.
