Identification of crystals in synovial fluids and joint tissues.

The identification of crystals in synovial fluids and joint tissues is the most rapid and accurate method of diagnosing the common forms of crystal-associated arthritis. Although there are numerous methods available for identifying and characterizing crystals in biologic specimens including x-ray crystallography and Fourier transform infrared spectroscopy, in practice, polarizing light microscopy is used almost exclusively for articular crystals. Unfortunately, problems with reliability and reproducibility undercut the usefulness of this simple procedure. This article highlights recent developments in the field and discusses the importance of identifying synovial fluid crystals, proper handling of specimens, and the appropriate use of available technologies for crystal identification.