A synovectomy is a relatively rare type of surgery for someone who’s experiencing significant problems with swelling and inflammation inside their knee joint. What sort of conditions would cause those problems? And how does the procedure help to solve them? Here’s a brief guide to the issues…
What and where is the synovium?
The synovium is a tissue membrane that lines the inside of your knee joints. It’s thin – usually just one or two cell layers deep. You could think of it as a bit like an inner skin on the surface of your joints.
What does the synovium do?
It protects the joints. It produces a liquid called synovial fluid, which contains important chemicals and enzymes like hyaluronic acid, lubricin and proteinase. This fluid nourishes and lubricates the different parts of your knee joint so that everything moves smoothly.
What problems can it develop?
The most common one is synovitis. This is where the synovium becomes swollen, inflamed and sometimes painful. Synovitis can have a variety of causes, such as trauma (eg a bad fall), irritation caused by “loose bodies” of broken-off cartilage, or inflammatory arthritis – a group of diseases that includes rheumatoid arthritis and gout. The good news about synovitis is that, for most people, it will settle down with conservative treatments like rest, ice and mild pain relief.
When might you need surgery on your synovium?
A synovectomy might be recommended if you’ve tried a range of other treatments and they just aren’t working. For instance, if you’ve been taking antirheumatic medicines (“DMARDS”) for rheumatoid arthritis for six months or more and your symptoms haven’t improved, your rheumatologist might refer you to us to see if a synovectomy would be appropriate. There are some other disorders of the synovium that often lead to surgery:
Pigmented villonodular synovitis (PVNS) – PVNS is a type of non-cancerous tumour that causes the synovium to thicken and grow bigger than normal. It can be uncomfortable, or quite painful, with significant swelling and sometimes catching or locking within the joint. If the PVNS is diffuse (spready widely), it’s quite likely to recur in the future, even after surgery.
Synovial chondromatosis – This condition causes the synovium to produce tiny, berry-like nodules of cartilage – sometimes hundreds or even thousands at a time. These can be either localised or widespread; they float freely within the joint, causing discomfort and, often, mechanical problems like locking of the knee.
How does the synovectomy surgery work?
The idea behind a synovectomy is to remove the inflamed synovium that’s causing your symptoms. How much of it depends on your own situation – it could be just a portion of the membrane (a partial synovectomy) or all of it. We can do this with open surgery or, more commonly, with keyhole surgery, which is less invasive. The idea of the synovectomy is to reduce the pain, swelling and functional problems you were getting with the inflammation in your knee.
What happens next?
Recovery after a synovectomy varies quite a lot depending on the type of procedure you had – it can take six weeks or even up to a year or so for some complex cases. Physiotherapy can help to improve the recovery time in either case. It’s worth noting that, unlike the articular cartilage that’s at the heart of osteoarthritis problems, your synovium will likely have the power to regenerate over time. Thanks to a good blood supply in this part of your knee, it’s likely to grow back over the next year or two. This can mean the inflammatory issues will happen again in the future. But that isn’t always the case. This is something we’ll discuss in detail with you during your assessment.
