No two ways about it: when a ‘Baker’s Cyst’ really gets going, it can look and feel pretty alarming.
This kind of swelling occurs behind the knee, often in the middle or slightly to the inner side, and in some cases can swell to the size of a grapefruit.
Not surprisingly, a lump on that scale – even though it’s usually quite harmless – can be debilitating to live with. Especially if it’s accompanied by pain.
So what causes these things? And what can be done about them?
What is a Baker’s Cyst?
A Baker’s Cyst (also known as a popliteal cyst) is a fluid-filled lump that occurs at the back of the knee, behind the knee joint. When fluid builds in the joint, the pressure can eventually force the fluid through into a tissue at the rear of the knee. At that point, it collects in the form of a cyst. This can become uncomfortable as the pressure builds up.
What do they tend to feel like?
It varies. Some people get pain or discomfort in the knee and calf area. Others find the swelling restricts their leg movement, particularly if the cyst becomes quite big. For many people, though, it’s essentially symptomless – except for a noticeable lump. Baker’s Cysts are relatively common. They’re more prevalent in women and people 40+, but they affect younger people too.
What causes them?
The root cause of a Baker’s Cyst is usually an issue back in the joint, where the inflammation begins. A typical cause might be a blow to the knee, for example, which tears the meniscus. But it can also be brought on by chronic conditions like osteo- or rheumatoid arthritis. If the condition worsens, the joint may produce more fluid, which in turn increases the size of the cyst. We think part of the issue may be a kind of one-way “flap-valve” mechanism that exists at the back of the knee; this valve allows fluid into the cyst, but not back into the knee. Either way, we’ll probably want to order an MRI scan, so we can identify the primary issue and treat it directly.
Will the cyst just go away in time?
The first thing anyone with a Baker’s Cyst wants to know is whether it will go away by itself. The answer is: it might. Some naturally dissipate over time, particularly if we address the underlying cause. Sometimes the cyst bursts and this can cause discomfort, which spreads into the calf muscle. That’s why we usually recommend conservative treatment for the cyst itself. Simple painkillers like paracetamol and ibuprofen (an anti-inflammatory) can be helpful. Ice packs can sometimes reduce the swelling and discomfort. Nine times out 10, conservative is the way to go. This might mean waiting for six months or so to see how it develops.
What if it doesn’t?
If a Baker’s Cyst gets particularly large, painful or persistent, other options may come into play. One is to drain the cyst. This is a simple procedure that involves “aspiration” at the back of the knee using a syringe and needle, often under ultrasound guidance. Another approach is a decompression, where we use keyhole surgery to gently widen the valve between joint and cyst so pressure can no longer build up on the other side of the valve. These procedures aren’t commonplace, but they are options to consider if the cyst is becoming a real problem.
In summary, then, a Baker’s Cyst is usually harmless, and most people who get one find that it resolves – either through treatment of the primary cause, or naturally in its own good time. It’s worth adding, or course, that lumps can have other causes – and for that reason, if you have a new lump that hasn’t yet been diagnosed, you should get it checked out to be on the safe side. Either book an appointment with your GP, or come and see us here at the clinic and we can diagnose you and explore the next steps.
To book an appointment with the surgery, hop to the contact page on our website – or drop the team a line direct on 01962 826107.