Swelling – like pain – is one of the body’s ways of telling us that something is going awry below the surface. When it comes to knees, there are lots of potential reasons why that might be happening – so if you do experience a swollen knee, it’s a good idea to arm yourself with a doctor’s diagnosis.
Today we want to focus on one of those possible causes. It’s something called synovitis, and we see it fairly frequently with our patients here in the clinic. What exactly is it?
Synovitis is a condition that affects (the clue is in the name here) the synovium. But what’s the synovium? Essentially, it’s a soft-tissue membrane that covers the inner surface of certain joints. It’s also known as the “synovial membrane”, for that reason. The synovium’s job is to protect our joints. It contains a substance called synovial fluid, which lubricates and prevents friction within the joint components. Synovitis is what happens when that synovial membrane becomes inflamed.
What symptoms does that typically produce in a knee?
One possible symptom is swelling, as we’ve mentioned. This can happen as the inflamed membrane thickens, and when the synovium begins to release excess fluid into the area. But swelling doesn’t always occur with synovitis. You could experience joint discomfort or pain because of the synovitis – which can be localised, or spread right across the knee. But synovitis isn’t always painful, even when there’s a lot of swelling around the knee.
What causes synovitis?
The synovium can become irritated for a number of different reasons. Trauma is the obvious one. If you’ve fallen, or taken a blow to your knee, you could see a sudden flare-up as the membrane reacts to the impact. Overuse of the joint – such as in running, or through a repetitive stress injury – can have a similar effect. Infection from a virus or bacteria is another possibility and, though rare, it’s important to rule this out. Another potential cause is inflammatory arthritis. This is a group of diseases – including rheumatoid arthritis and gout – which are caused by an overactive immune system. It’s also possible that degeneration within the joint is affecting the synovium. “Loose bodies” – tiny chunks of cartilage that break away from the joint – can irritate the synovial membrane. Long-term wear-and-tear of the cartilage (osteoarthritis) can also cause synovitis flare-ups.
How do you treat synovitis?
The first thing we need to do is determine that underlying cause. We can do this partly with a physical examination. We’ll often accompany that with a scan, and blood tests to check for raised “inflammatory markers” in the body. Occasionally, we’ll do an aspiration (draining liquid from the knee with a surgical needle so it can be tested), or a biopsy (removing a small piece of tissue from the synovium) to see if there’s any to see if there’s any focal abnormality within the knee, such as a localised lesion, swelling or lump that may have been identified on an MRI scan. Sometimes we might refer you to our colleagues in rheumatology.
What would happen next?
Once we’ve established the root cause of the synovitis, we can create an appropriate treatment plan to resolve or manage it. Part of this may involve reducing those inflammatory symptoms. The good news is that many cases of synovitis settle down fairly quickly, so in the first instance we may simply recommend rest, icing, or mild pain relief (such as ibuprofen, if you are able to take it, which is an anti-inflammatory) until it subsides naturally. The key thing is to get a proper medical diagnosis and move on from there.
Are you concerned about swelling, inflammation or pain in your knee and wondering what might be causing it? Please drop us a line today; we’ll be glad to help. You can call us on 01962 826107 – or book an appointment through the website.