If you’ve ever had a Baker’s Cyst, you’ll know they can be a bit disconcerting.
You first notice a lump at the back of your knee, in the concave flex of the joint. It probably isn’t painful (though they sometimes can be). But you know it shouldn’t be there. And if it grows larger, it can feel rather alarming: some Baker’s Cysts can swell to the size of a golf ball – or even a grapefruit. By that point, obviously, you may find it starts to become uncomfortable and restrictive.
Most Baker’s Cysts don’t get so big, fortunately. In fact, some people develop one without even noticing it’s there. After all, how often do you feel the backs of your knees?
There are two reassuring things to say about Baker’s Cysts. First, they are usually harmless. Second, they often simply go away by themselves; it may just be a case of waiting until the cyst dissipates naturally, and we or a doctor can help advise you about this. We would want to first properly diagnose the Baker’s Cyst with a physical examination of your knee, and possibly with an MRI scan as well.
Approach 1: treat the underlying issue
Having said that, a Baker’s Cyst can be a bit of a “window into the knee”. It could indicate something else is going on in your knee joint. That’s because the cyst is essentially an excess of synovial fluid – the thick, lubricating liquid your body produces to reduce friction within joints. So we would want to ask why that inflammation is happening. The answer could be something like osteoarthritis, where the joint produces more fluid in response to loss of cartilage and the resultant, painful rubbing between bones. Or it might have been caused by trauma – a heavy fall, perhaps, or a knock to the knee while playing sport, resulting in a cartilage tear. In cases like these, treating the underlying inflammatory problem may well be the solution for the Baker’s Cyst.
Sometimes, though, the cyst may need a helping hand and some direct treatment.
Approach 2: treat the cyst conservatively
In the vast majority of cases, conservative management is the way to go with a Baker’s Cyst. There are a number of simple things we might recommend you do at home to reduce the swelling and encourage the cyst to subside naturally. These include:
R.I.C.E.: The well-known RICE approach to injuries – Rest, Ice, Compression, Elevation – may be helpful. Since stress to the joint can cause inflammation, pausing certain activities and resting your leg gives the tissues time to recuperate. Icing the knee can help to reduce inflammation within the joint, and using a compression bandage, sleeve or wrap (available from chemists) has a similar effect (though it could potentially cause discomfort if pressing too tightly on the cyst). Elevating the leg when possible may also help to reduce swelling.
Simple medication: If you’re able to take them, NSAIDs can also reduce swelling. NSAID stands for non-steroidal anti-inflammatory drugs. Common ones include ibuprofen and naproxen, both available over-the-counter. These medicines also provide some pain relief.
Approach 3: treat the cyst with surgery
It’s really quite rare to recommend surgery for a Baker’s Cyst. But we do sometimes do it. As the NHS puts it, “further treatment will only be needed if the cyst stops you using your knee or causes persistent pain.” In other words, it’s causing you considerable distress or disruption. There are two main operations we might use to tackle it:
Aspiration: Aspiration means draining fluid from the knee joint with a surgical needle. This is normally performed using an ultrasound probe, which guides the needle safely through the back of the knee and the nerves and blood vessels there. The procedure usually takes about 15 minutes. Afterwards, we simply apply a dressing and you can go home. It’s worth adding, however, that aspiration tends to be a temporary, short-term ‘fix’ rather than a long-term solution. The cyst often returns – though not always to the same degree, which can make the operation worth considering.
Decompression: Decompression is quite a specialist technique that we perform using keyhole surgery and a surgical camera. The idea here is to target the ‘flap valve’ mechanism that sits between the joint and the cyst. The surgeon first creates some small ‘portals’ at the back of the knee. We then make a series of small incisions to widen the valve. This can essentially relieve the pressure build-up on the cyst, causing the gelatinous material inside to flow back into the knee joint. In other words, the procedure doesn’t eliminate the cyst itself. It just eases off the fluid that makes it swell up. Decompression isn’t a miracle cure for Baker’s Cysts; on average, about 50% of patients see a long-term benefit after having the surgery.
For those reasons, choosing aspiration or a decompression is likely to come down to how much discomfort, loss of mobility, or pain it’s causing you. If you’re like most people, the effects of a Baker’s Cyst should be mild. Sometimes the cyst will remain permanently but cause no problems. Sometimes it will disappear over time. But as with all lumps – and indeed with anything that causes you concern or worry – it’s a good idea to have it diagnosed first.