What are bakers cysts in the knee?
Figure 1: Knee Pain - Bakers Cysts - Physio Frenchs Forest, Physio Macquarie Park
What is a Baker’s Cyst?
A Baker’s Cyst (otherwise known as a Popliteal Cyst, due to its anatomical position) is a collection of fluid at the back of the knee. These cysts can sometimes cause pain in the posterior knee, but can also be asymptomatic. The presence of a popliteal cyst is very rarely a primary condition, but rather indicates a potential pathology affecting the knee joint.
Relevant anatomy/pathophysiology:
The popliteal fossa is the area behind the knee, between the femur and the tibia. A number of important blood vessels and nerves run relatively superficially through this area. Muscles such as the hamstrings and gastrocnemius (calf muscles), and their tendons also cross through the same area.
Deeper than this fossa is the capsule of the knee joint itself, a thick connective tissue sack that encapsulates the articular surfaces of the knee. Due to weaknesses in the posterior knee capsule, any fluid build up in the knee is more likely to push on the back of the capsule, and if enough fluid is present, extend into the popliteal fossa, causing a Baker’s cyst.
Bursae are sacs of fluid present in the body, and they help to lubricate certain joints, as well as acting like shock absorbers in some situations. Bursae exist in the posterior knee, and if they become inflamed and fluid escapes from them, it is once again likely to pool in the popliteal fossa, causing a cyst like swelling in the empty space.
As previously stated, a Baker’s cyst is a secondary condition, and is often the result of swelling and inflammation caused by conditions such as; osteoarthritis, ACL or meniscus tears, gout, or post. operative complications.
Clinical presentation:
A patient suffering from a Baker’s Cyst is likely to exhibit the following symptoms:
Posterior knee pain, often worsened by bending of the knee
A palpable mass or swelling behind the knee
Reduced knee range of motion
Posterior pain that is worsened with activity
A sensation of stiffness in the popliteal region
Possible complications:
It is possible for a Baker’s Cyst to rupture, which is the most common complication seen involving popliteal cysts. Patients who suffer from a ruptured Baker’s Cyst often complain of a sharp pain at the back of the knee, and the sensation of liquid dripping down the back of the calf muscle. In some circumstances a bruise can appear around the ankle joint. It can take a few days/weeks for this fluid to reabsorb into the body.
Figure 2: Knee Pain - Bakers Cysts - Physio Frenchs Forest, Physio Macquarie Park
Management:
As previously stated, a Baker’s Cyst is an indication that a pathology exists within the knee joint itself. Therefore, treatment for a popliteal cyst should involve treating the underlying condition that caused the cyst in the first place.
Your physiotherapist will assist you in managing a Baker’s Cyst by educating you on movements or activities that you should avoid, as well as providing you with an exercise program to strengthen the muscular structures surrounding the knee and improve your range of motion. In most cases, they will also be able to help you conservatively manage the underlying condition that caused the cyst to form initially.
In terms of medical management, your general practitioner may opt to drain the cyst to relieve your symptoms. This can result in short term relief, but does not guarantee that the cyst will not return. In certain cases, a corticosteroid injection may be used to reduce inflammation in and around the knee, but again, this does not guarantee complete resolution of the popliteal cyst.
See our expert Physiotherapy team at Frenchs Forest and Macquarie Park!