A Baker’s cyst, also known as a popliteal cyst, is a fluid-filled swelling that forms behind the knee. It typically arises when an underlying issue within the knee, such as arthritis or a meniscus tear, causes the joint to produce excess fluid. This fluid then accumulates in a bursa behind the knee, leading to the formation of the cyst.
Common Symptoms and Progression
An untreated Baker’s cyst can lead to persistent symptoms that impact daily life. Individuals commonly experience ongoing pain or discomfort in the back of the knee, which can intensify with activity or prolonged standing. This discomfort is frequently accompanied by a noticeable swelling or a palpable lump behind the knee.
The presence of the cyst can also lead to increased stiffness and a restricted range of motion in the knee. Bending or fully straightening the leg often becomes difficult, limiting activities such as walking, climbing stairs, or even sitting comfortably. If the underlying knee problem remains unaddressed, the cyst may continue to enlarge, potentially worsening symptoms over time. Their ongoing presence can significantly diminish an individual’s quality of life and hinder routine tasks.
Potential Complications
Leaving a Baker’s cyst unaddressed can lead to several serious complications. A primary concern is cyst rupture, which occurs when the fluid-filled sac bursts due to increased pressure. This event can cause sharp pain in the knee and calf, followed by rapid swelling, redness, and bruising that extends down the calf, sometimes resembling a deep vein thrombosis (DVT). The ruptured fluid can leak into the surrounding calf tissues.
A large Baker’s cyst can also compress nearby nerves. This nerve compression can result in numbness, tingling, or weakness in the lower leg and foot. An enlarged cyst can even press on blood vessels, potentially affecting circulation to the lower leg. This vascular compression can lead to leg edema or, in rare instances, popliteal artery obstruction.
When Medical Consultation is Advised
It is important to seek medical advice if an untreated Baker’s cyst begins to cause concerning symptoms. Sudden, severe pain behind the knee or in the calf warrants immediate evaluation, especially if accompanied by rapid or significant swelling. Skin discoloration, such as redness or bruising in the calf area, is a warning sign that requires prompt medical attention.
Any new onset of numbness or tingling in the foot, or weakness in the lower leg, suggests potential nerve involvement and should be assessed by a healthcare professional. Additionally, signs of infection over the cyst, such as increased warmth, redness, or fever, indicate a need for urgent consultation. While many Baker’s cysts are benign and may resolve on their own, these symptoms can mimic more serious conditions like deep vein thrombosis (DVT), making a timely medical assessment important to ensure proper diagnosis and treatment.