A Baker's cyst, also called a popliteal cyst, is a fluid-filled cyst that causes a bulge behind the knee. A Baker's cyst can cause a feeling of tightness behind the knee, and the pain usually gets worse when the knee is fully extended or during physical activity. Knee arthritis or cartilage tears can lead to a cyst formation. This is because both conditions can lead to increased fluid production.
Mechanism of Action
Intra-articular knee disorders, such as osteoarthritis and meniscus tears, are commonly found in association with a Baker's cyst. Cartilage degradation causes increased pressure on the knee, leading to fluid accumulation. A valvular opening of the posterior capsule (a one-way valve) allows fluid to pass into the gastrocnemius-semimembranosus bursa.
It is common for effusion to occur in intra-articular knee disorders, leading to the hypothesis that a Baker's cyst formation is likely occurring to provide protection for the knee. Transporting the excess fluid to the back of the knee decreases the hydraulic pressure within the knee through this one-way valve. This is supported by a study that showed the volume of a Baker's cyst is associated with the size of the knee effusions. The cyst wall resembles synovial tissue with fibrosis, and is characterized by chronic inflammation.
TCM Treatment
Conventional treatment of a Baker's cyst typically results in surgery. Although surgical excision can remove the cyst, there is a high recurrence rate since treatment for intra-articular knee disorders can be difficult.
Traditional Chinese medicine (TCM) categorizes cysts as a stagnation which occurs from a blockage such as arthritis. Arthritis causes a blockage in the smooth flow of qi and blood. It is imperative to address both the cyst and the intra-articular knee disorder that is causing the blockage.
Applying Chinese herbs externally to the cyst and the affected joint can help repair the intra-articular knee cartilage injury, and reduce the knee inflammation and effusion to shrink the cyst. Chinese herbs such as clam shell and oyster shell can help to break down the fibrosis and inflammation of the cyst to decrease the diameter.
Chinese herbs such as Chinese angelica, myrrh and twotooth achranthes root have been shown to increase blood flow to provide nutrients necessary for tissue repair; as well as decrease inflammation to allow those nutrients to enter into the synovial fluid. Twotooth achranthes root has also been shown to promote chondrocyte proliferation, which helps to rebuild and maintain cartilage that has been destroyed by the intra-articular knee disorder.
By addressing the disorder causing the effusion, the hydraulic pressure within the knee will be decreased, along with the recurrence rate.
Sample Case Study
Increased ROM in Baker's Cyst Patient — Marla Evans, NT, Texas
When Marla was younger, she tore her medial meniscus and had it removed. It is very common for patients who have had meniscus injuries to develop Baker's cysts develop later in life; this was the case for Marla. As the cyst began to grow, Marla gradually lost her ability to bend her knee and walking became excruciatingly painful.
To treat the swelling in her knee, she sought out cold-laser treatment. On her best days, Marla was only able to bend her knee approximately 80 degrees. Long walks or any exercise on foot for Marla was out of the question.
In Marla's search for alternative treatments, she found a TCM-based wellness recommendation that included external Chinese herbal patches consisting of herbs such as Chinese angelica, myrrh, twotooth achranthes root and 12 other all-natural Chinese herbal ingredients. In the first three days of treatment, the cyst decreased to the extent that she was able to bend her knee 90 degrees – a 10-degree increase in range of motion (ROM). On top of the improved flexibility, Marla's pain from walking was reduced.
Marla has also been going to physical therapy. After four weeks of treatment, Marla had a 20 percent improvement in her ROM. The normal ROM for a knee is 135 degrees. Before Marla started her treatment, she had 60 percent knee movement at around 80 degrees; now, she has 80 percent knee movement at 108 degrees, with the size of the cyst reduced by 99 percent.
At the end of Marla's treatment, she was ecstatic with her results and is going to start treating an injury in her other leg.
Dr. Sarah Li is the founder of Wei Laboratories, Inc. (www.weilab.com), which offers a full range of Chinese herbal products with compressive training and services. Representative products include FASTT Patch and WHITEE Patch that address many tough-to-treat musculoskeletal conditions. Dr. Li attended the University of Science and Technology of China, majoring in biology and graduating with the highest honor as the valedictorian; and completed her PhD in Biochemistry at the University of Minnesota, Twin Cities. Dr. Li accomplished her research fellowship at Beth Israel Hospital, focusing on the pathogenesis of type II diabetes. She also worked as a research associate at Harvard Medical School.