Young Man, Swollen Knee

By Dr Irwin Lim, Rheumatologist

Young 20-something year-old man walks into their health professional's clinic.

"My right knee just started to become painful and a few days later, the swelling just grew".

Sure, he's an active guy and plays sport like many do.

But, the answer is not always sport.

What's the question that should come to mind?

Is this due to mechanical/degenerative disease or it there an underlying inflammatory arthritis?

If there's a history of trauma or there was a distinct injury on the football field with him limping off, you may be more worried about mechanical issues, for eg, a ligament tear.

If he's had multiple injuries over a period of time in that same knee, and has known damage there, you will be considering possible mechanical and degenerative reasons for this swelling.

If you don't have the above, consider an inflammatory arthritis cause!

How to work out what the cause is?

Well, we'd rely on a combination of:

• a full history including details about seemingly unrelated conditions (for eg, psoriasis or bowel habit)
• the actual physical examination including in areas apart from the knee involved
• investigations such as blood tests and possibly, radiological examintions

I'd also advocate that the fluid in that joint be drained.

Synovial fluid (the joint fluid) is valuable. It can be sent to the lab and analysed. This will differentiate between mechanical/degenerative causes and inflammatory causes. It may actually help determine the actual cause of inflammatory arthritis as in the case with gout or pseudogout.

The point of this post is to remind people that we shouldn't automatically treat all swollen knees as due to "wear and tear".

This happens way too commonly.