It is an inflammatory joint disease which is caused by an extraarticular infection. However, there is absence of bacteria in the joint. Reactive arthritis usually occurs one to four weeks following a remote infection, especially enteric or genitourinary.
An example is Reiter syndrome which has a triad of arthritis, conjunctivitis and urethritis. There is erythema and marked pain in the joint. ESR and CRP are elevated. HLA B27 positivity predicts chronicity and severity.
Treatment is mainly NSAIDs as the condition is usually self limiting. Intra-articular steroids, systemic steroids or even immunosuppressive agents can be used in severe and chronic cases.