Monoarthropathy. Could this be infection?

Monoarthritis in an adult presents a diagnostic challenge. Monoarticular symptoms usually imply local joint pathology, but may be a referred phenomenon, a feature of a periarticular syndrome such as a stress fracture or the dominant manifestation in polyarticular disease.

When confronted with an acute or subacute monoarthritis, exclusion of sepsis is essential and wherever feasible joint aspiration and diagnostic analysis of synovial fluid should be undertaken.

A history of joint stiffness, restricted joint movements and the presence of an effusion are generally helpful indicators of true arthritis. Synovial fluid examination is the single most informative investigation that can be performed in this clinical setting. It should include a total and differential leucocyte count, scrutiny for crystals under polarized light and microscopy and culture for organisms. In the absence of organisms or crystals, the presence or absence of blood in the aspirate and the number and type of leucocytes will assist in the differentiation of other diagnostic possibilities.