Problem based review: The patient with acute monoarthritis.

Acute monoarthritis is a common medical emergency with wide differential diagnosis. Common underlying causes include trauma, septic arthritis, crystal induced arthritis (gout and pseudogout), and reactive arthritis. Of these, septic arthritis is the diagnosis not to miss because of its association with significant morbidity and mortality. Precise diagnosis of the underlying cause of monoarthritis relies on a good history, physical examination findings, and results of focussed investigations. In this article, a practical approach to diagnosis and initial management of patients presenting with acute monoarthritis is described with the aid of a case vignette.