Baker’s Cyst

Baker's cyst

A Baker’s cyst, which was named for William Baker who first diagnosed it in 1877, is  also known as a popliteal or a synovial cyst of the knee. It is defined as a swelling at the back of the knee caused by the retention of fluid in the knee joint. The fluid that is retained is called synovial fluid, and while it is the natural lubricant in all joints, an excess of this fluid is problematic. In Baker’s cysts, the synovial fluid gets pushed into the weakest part of the knee capsule, the popliteal region at the back of the knee. Importantly, these do not appear as a tumor or growth, which the name ‘cyst’ often implies. As the fluid is compressed between the bones of the knee by the pressure from body weight, it becomes trapped, and forms a fluid-filled sac. Tightness in the muscle and joint area will likely be felt, although it is possible that patients may see or feel little to no symptoms. Any condition that induces swelling, including arthritis, cartilage tears, and meniscus tears, can cause a Baker’s cyst to form; about 50% of osteoarthritis sufferers will get them.

Baker’s cysts can affect people both young and old, although they are unlikely to cause complications in children; these cases are likely to resolve on their own. Younger people  will not usually have a connected area of fluid from the cyst towards the knee joint, but older people will, usually indicating that there is  some other deficiency in the joint. Older patients’ Baker’s cysts are also likely to have thicker walls, compartmentalization of the cyst, and debris floating within the synovial fluid of the cyst. This is sometimes known as a complicated Baker’s cyst.

Because symptoms of a Baker’s cyst may be quite mild, and because the cyst may shrink on its own, even if only to reappear again, patients may hesitate to seek treatment. However, there are a number of reasons for proper treatment. There are many possible complications of a Baker’s cyst, including continuous growth of the cyst and worsening symptoms, extension of the cyst into the calf muscles, and rupture and leaking of the fluid, leading to bruising in the ankle. Although unlikely, even more grave consequences, like tumor development, compressed nerves, and popliteal artery aneurysm may follow. One of the more common complications in untreated Baker’s cysts is  rupture. In these cases, the synovial fluid leaks down into the calf muscles, causing sudden, sharp, radiating pain that presents quite similarly to deep vein thrombosis (DVT) — otherwise known as a blood clot. To complicate matters further, having Baker’s cysts, even if unruptured, increases the likelihood of developing deep vein thrombosis. And because DVT is a serious condition that should always be tested for if suspected, the complicated differential diagnosis between DVT and a Baker’s cyst is necessary.

We offer ultrasound guided cyst aspiration with consecutive injections of cortisoneprolotherapyPRP (platelet-rich plasma) injections, medication, physiotherapyacupunctureactive exercises,  psychotherapy,  biofeedback, and assistive devices such as bracesTENS/MET devices, and orthotics for patients who suffer from baker’s cysts.



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