What is a Baker’s Cyst

A Baker’s cyst, also known as a popliteal cyst, was originally named after the surgeon who first described it, William Morrant Baker (1838-1896). It is not a “true” cyst, which is described as a closed capsule of air, fluid or other material. A Baker’s cyst is a bulging or swelling at the back of the knee. An excessive build up of synovial fluid, that is normally lubricating our knee joint, gets pushed into the cavity at the back of the knee. This may be in response to osteoarthritis in the knee, a meniscal injury, cartilage damage, rheumatoid arthritis or any knee condition that causes joint inflammation.

The knee joint is comprised of the femur (thigh bone) and the tibia (long shin bone). Between these bones are two round discs of cartilage, called the meniscus, that act as a shock absorber during weight bearing activities. Wrapping around the whole joint is a strong connective tissue, called the capsule, that surrounds the joint complex. Behind the knee, lie a few small fluid filled sacs called bursa. These bursa, which surround all our joints in the body, are designed to reduce friction between adjacent bony structures or soft tissue layers.

We may have damage to the knee from repetitive or prolonged activities, excessive weight bearing or twisting motions, degenerative changes or a traumatic event such as a fall. Swelling may accumulate and get pushed into the bursa at the back of the knee (the popliteal space), which becomes a Baker’s cyst.

Symptoms may include tightness or stiffness behind the knee, pressure or pain with knee flexion, calf pain, or increased swelling and discomfort with standing. Sometimes the pocket of fluid behind the knee can break and drain into the lower leg. This may cause swelling and redness in the calf. It is important to differentiate this condition from a deep vein thrombosis. If you have insidious onset pain in the calf, redness, tightness, pain with walking but relief with rest – you must seek immediate medical attention as this could be the symptoms of a blood clot in your lower leg. Especially if these latter symptoms have arisen after a recent traveling experience, please seek attention immediately!

A Baker’s cyst typically feels like a firm bulge at the back of the knee. As the condition worsens, you may experience pain or pressure with bending or straightening the knee. These symptoms may also be associated with clicking, grinding, locking, limping, sharp pains or pain with certain activities (kneeling, twisting, squatting). A thorough subjective and objective examination by a physiotherapist is helpful to diagnose a Baker’s cyst and the underlying cause of the condition. This is the key phrase here – the underlying cause! Often a Baker’s cyst is secondary to an underlying injury, imbalance or condition in the knee. Other investigations such as an ultrasound, X-ray, MRI or CT scan are used to confirm a diagnosis.

Treatment primarily involves treating the underlying cause of the condition. Some Baker’s cysts require no treatment and cause little or no symptoms. Generally, the initial phase is to follow the RICE regimen (rest, ice, compression and elevate) in the first 48- 72 hours. Anti-inflammatory medication may also help to hasten healing and recovery by reducing the pain and swelling. One should perform pain free range of motion at the knee and strengthening exercises to help facilitate joint lubrication and muscle flexibility. Targeting the quadriceps, hamstrings, gluteals and calf muscles will help to improve the control the knee joint with weight bearing activities. A treating physiotherapist can advise which exercises are most appropriate and when they should be commenced. We may also integrate soft tissue release, joint mobilization, dry needling techniques, acupuncture, taping / bracing, and education on biomechanical corrections and muscle imbalances in the body.

Patients that are not responsive to appropriate physiotherapy treatment may seek other options such as a cortisone injection, aspiration of the fluid filled sac, or in rare cases, surgery.

If any of this information sounds familiar to you and you think you may have a Baker’s cyst, we would love to help you and get you back to feeling your best and enjoying your favorite activities!

Jennifer Gordon (BScPT, AFCI, GIMS, BKin)