Sonographic diagnosis of an arterioarticular fistula following knee arthrocentesis.

An arterioarticular fistula is an unusual complication of knee arthrocentesis. We describe the sonographic findings immediately following a failed clinical attempt at knee arthrocentesis that resulted in an arterioarticular fistula. Spectral Doppler analysis confirmed the jet of blood into the hemarthrosis. Knowledge of anatomy and application of standard technique is necessary to minimize the complications of arthrocentesis.