Measurement of synovial fluid volume using albumin dilution upon intraarticular saline injection

A simple method for measuring synovial fluid (SF) volume is described. The degree of dilution of SF albumin after intraarticular injection of a defined volume of saline was used to calculate residual SF volume. Good correlation between calculated and aspirated SF volume was found for knee joint exudates. The method is simple, requires no radioactive tracer and should be useful in quantitative studies involving SF pathophysiology. Interestingly, the major portion of the SF could be directly aspirated, since residual volumes were small in comparison.