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What is a Baker's Cyst? Baker's cyst is the accumulation of fluid in the bursa known as gastrocnemio-semimembranosus bursa, which lies in the popliteal fossa behind the knee joint. Causes, Incidence and Risk Factors Any type of joint disorder of the knee manifests itself as joint effusion. The extra synovial fluid is pushed back and forms a cyst, to prevent excessive pressure on the joint. There is a relation between the cyst and the knee joint cavity. Popliteal cyst occurs less commonly in children than in adults and always has an underlying pathology. In the majority of cases of Baker's cysts, there is an underlying form of arthritis that causes effusion in the joint space. Apart from arthritis other risk factors for popliteal cysts are: - Trauma causing meniscal tear, ligament tear or fractures
- Joint infection
- Dialysis
- Hemophilia
- Hypothyroidism
Signs and Symptoms A mass in the back of the knee (popliteal mass) is the most common presenting symptom, which may either be painful or painless. The swelling may feel like a water filled balloon. In almost all the cases, the mass has some movement under the skin. The cyst may burst causing pain, bruising and restriction of motion. Screening and Diagnosis In order to diagnose a Baker's Cyst, physicians will commonly perform: Physical examinationsX-rays to detect the mass and calcificationsUltrasound to evaluate whether the mass whether is solid or fluid-filledColor Doppler is done to rule out aneurysmsMRI is used to confirm the fluid communication between the cyst and the knee joint.Treatment Baker's cysts are treated conservatively with support therapy while the underlying joint disorder is treated. Adequate rest is necessary for the knee to heal properly. Non-steroidal anti-inflammatory drugs (NSAIDs) are prescribed for relieving the associated pain and inflammation. Some people also benefit from applying ice-packs. In addition, an assistive weight-bearing device, such as a walker or crutches, is recommended to relieve pressure form the knee joints. This will ensure that activities are resumed with minimum discomfort. Radioactive synoviorthosis can be used to treat joint disorders associated with various types of arthritis. It is done by instilling a radioactive substance into the joint cavity. If a cyst does not respond to medical management, a surgical excision of the cyst may be done. Prevention The occurrence of a Baker's Cyst can be prevented by avoiding injury to the knee joint. The strength and flexibility of the knee joint should be maintained. Recurrence of the cyst after treatment can be prevented by adequate treatment of the underlying cause. |
