Knee effusions.

There are many questions concerning knee effusions and the basic diagnostic approach to them. The case of a young female with gonococcal arthritis presenting to the Emergency Room with an isolated knee effusion is discussed. From the errors in diagnosis of this case, a basic outline in the approach and work-up of a knee effusion is detailed, including history and physical examination, and the use of synovial fluid analysis as a further diagnostic aid. Procedural instructions and contraindications for knee arthrocentesis are given, as well as data related to interpretation of pertinent laboratory findings of synovial fluid in disease states.