Should I be worried about my Baker’s cyst?
What is a Baker’s cyst?
A Bakers cyst is a fluid filled sac that lies at the back of your knee. The cyst communicates with the knee joint and fluid travels from within the knee, into the cyst. It is often an incidental finding on an MRI. Most patients do not have symptoms related to their Baker’s cyst.
In some patients, the cyst is a sign that there are problems within the knee such as:
Osteoarthritis
Meniscus tears
Inflammatory arthritis
Gout
These problems can cause swelling within the knee. The excess fluid within the knee drains into the Baker’s cyst and causes it to enlarge.
What are the symptoms of a Baker’s cyst?
As a Baker’s cyst increases in size, patients complain of a dull ache or a sense of fullness at the back of the knee. The pain is sometimes worse when the knee is in a straight position. If the cyst is large enough, you will be able to feel a lump at the back of the knee and it may prevent you from bending the knee fully.
What happens when the cyst ruptures?
A Baker’s cyst can rupture and cause the contained fluid to leak into the calf. This may cause severe pain, swelling and redness within the calf. The fluid will gradually be reabsorbed by the body within a few weeks. It is important to seek medical attention if the pain is severe as there may be other causes for the pain.
How is it diagnosed?
The first investigation that should be organised in people with knee pain is a knee X-ray. This will show if the knee is arthritic, which may be the cause of the Baker’s cyst. An ultrasound or MRI can show the presence of a Baker’s cyst. Although the ultrasound is highly accurate in diagnosing a Baker’s cyst, it is unable to detect problems within the knee with accuracy. An MRI scan can accurately diagnose a Baker’s cyst, but also the other spectrum of related disorders such as arthritis, meniscal tears and cartilage injury.
Knee MRI scan showing a large Baker’s cyst at the back of the knee in a typical position. The cause in this patient was osteoarthritis and a torn meniscus.
How do you treat a Baker’s cyst?
A Baker’s cyst may fluctuate in size with time. Simple measures like using an ice pack, taking simple painkillers (like anti-inflammatory medication or paracetamol) can help.If the pain does not improve with these simple measures, consider seeing a specialist.
Drainage of the cyst using a needle and an injection of steroid can help with the symptoms. This is usually performed by a radiologist with ultrasound guidance. Over time, the fluid may re-accumulate.
Surgery is a consideration if you are in serious pain. The mainstay of surgical treatment involves dealing with the problem within the knee joint e.g. arthritis. This usually resolves the symptoms related to a Baker’s cyst.Occasionally, if a Baker’s cyst is large enough, it can be excised via open surgery. However, there is a chance that the cyst will recur despite being surgically removed.
Summary
A Baker’s cyst by itself is usually not a cause for concern. However, it is a sign there there may be something wrong within your knee.