A Baker’s cyst, also known as a popliteal cyst, is when the production of synovial fluid in the knee increases, accumulating at the back of the knee. Patients often feel swelling in this area, and when pressure builds up, fluid bulges into the back of the knee. It’s most common in patients suffering from gout, injury, arthritis, or inflammation within the joint lining. To treat Baker’s cyst, doctors need to deal with the underlying cause, otherwise, there can be ruptured Baker's cyst or the cyst may return after treating.

Symptoms of Baker’s Cyst

Although Baker’s cyst doesn’t often cause pain, patients may experience the following symptoms:

• Stiffness and tightness at the back of the knee.
• Swelling in the area behind the knee. This may worsen when you stand up.
• Mild pain at the back of the knee, radiating into the upper calf. This is most common when bending or fully straightening the knee.

Occasionally, patients may suffer a ruptured Baker’s cyst, where the bag of fluid breaks open and drains into the lower leg tissues. This may lead to redness and swelling in the affected leg region.

Causes of Baker’s Cyst

Any accumulation of synovial fluid, the fluid lubricating the knee joint, can lead to swelling, resulting in a Baker’s cyst. A ruptured Baker’s cyst often develops alongside other conditions, including:

• Meniscal cartilage tears in the knee
• Arthritis within the knee (common in older patients)
• Rheumatoid arthritis
• Other knee issues

Diagnosis of Baker’s Cyst

A medical professional will be able to diagnose a Baker’s cyst by standing behind the patient, who has their knees completely extended. The cyst can then be felt (palpated) when the knee is slightly flexed. The diagnosis of Baker’s cyst will usually be confirmed using ultrasonography or magnetic resonance imaging (MRI). However, sometimes, if popliteal aneurysm is not suspected, the doctor may take an aspiration of the synovial fluid from the cyst.

A rare but possibly fatal complication of Baker’s cyst is deep vein thrombosis (DVT). If you have Baker’s cyst, your doctor will need to quickly determine whether DVT is a possibility, using urgent ultrasonography and blood tests. DVT can occur when the Baker’s cyst is squeezing the blood vessels in the leg, resulting in leg edema and the formation of a blood clot.

Treatment for Ruptured Baker’s Cyst

The Baker’s cyst usually does not need any treatment and it will disappear on its own. However, when the cyst bursts, you may need some self-care treatment for the pain.

• Non-steroidal anti-inflammatory drugs (NSAIDs): These have antipyretic (anti-fever) and analgesic (pain-killing) effects. At higher dosages, NSAIDs also reduce the inflammation and swelling associated with cysts.
• Rest: To reduce knee irritation, you must rest your knee as much as possible. Your doctor or physical therapist can advise you as to how long you should rest, and may be able to recommend alternative exercises and activities.
• Icepacks: These decrease inflammations in the affected area. Be careful not to apply the ice directly to your skin.
• Crutches: Using crutches allows you to take any weight off the knee and walk without any pain.

If you are not getting any relief from these techniques, or if the swelling is especially painful or big, you may need additional treatment, such as:

• Injected corticosteroids, for example cortisone. These decrease swelling and inflammation.
• Physical therapy: A qualified physical therapist will be able to recommend some gentle range-of-motion and strengthening drills for the knee muscles. These exercises will be designed to decrease your symptoms and also maintain knee function.
• Arthroscopy: If there is extensive injury to the knee, a surgeon may have to remove the cyst and repair the knee joint. During arthroscopy, the joint is examined and any problems treated using an arthroscope, a thin, flexible fiberoptic tube. General or local anesthetic may be used, depending on the amount of knee joint repair needed.

Prevention of a Baker’s cyst

Knee joint trauma during exercise and sporting activities is common. You can reduce your chances of developing Baker’s cyst and, if you’ve previously been treated for Baker’s cyst, stop the condition from recurring by taking care to prevent knee injuries with the following steps:

• Gently go through the range of motions needed for your sport to warm up the knee joint and surrounding soft tissues.
• Stretch your muscles before beginning your activity.
• Choose appropriate and supportive footwear.
• When you turn, aim to do it on the balls of your feet, instead of through the knees.
• Always cool down after exercise using gentle, slow stretching.
• If you do feel a knee injury, stop what you’re doing straight away. Apply an ice pack to the area to ease any swelling. You’ll need to get further advice from a medical professional.