Hello and welcome to the Zero to Finals podcast. My name is Tom and in this episode I'm going to be talking to you about reactive arthritis.

And if you want to follow along with written notes on this topic, you can follow along at zero tofinals.com slash reactive arthritis or in the rheumatology section of the zero to finals medicine book.

So let's get straight into it.

Reactive arthritis is where synovitis occurs in joints as a reaction to a recent infective trigger.

And remember, synovitis is inflammation of the synovium, which is inside the joints and acts like a cushion to keep the joints from wearing out.

Reactive arthritis used to be known as rita syndrome. So you might still see that appearing in older textbooks or potentially in your exams.

Typically, it causes an acute monoarthritis. And a monoarthritis is a

single joint and it's acute because it comes on fairly quickly. And often this is a single

joint in the lower limb, most often the knee. And it presents with a warm, swollen and painful

joints. The obvious differential diagnosis is

septic arthritis, which is infection in the joint, but in reactive arthritis, there's no joint

infection. The most common infective triggers for reactive arthritis are gastroenteritis or sexually

transmitted infections. Climidia is the most or sexually transmitted infections.

Chlamydia is the most common sexually transmitted infection that causes reactive arthritis.

Conorrhea commonly causes a gonoccal septic arthritis. So if somebody's got a recent

sexually transmitted infection, you need to think about both reactive arthritis but also

septic arthritis. As far as pathophysiology is concerned, essentially what is happening is that

the immune system is responding to the recent infection, whether that's a gastroenteritis or

sexually transmitted infection or an other infection,

and the immune system response also causes antibodies or inflammation that affects joints.

There's a link with the HLA B27 gene, and it's considered part of the seronegative spondolo

arthropathy groups of conditions

...