Detection of ankle effusions: comparison study in cadavers using radiography, sonography, and MR imaging.

OBJECTIVE: The purpose of this study was to compare radiography, sonography, and MR imaging in revealing ankle effusions in cadaveric specimens.

MATERIALS AND METHODS: Known quantities of saline solution were instilled in increments into the ankle joints of three cadaveric specimens. Imaging was completed after each injection with the ankle in dorsiflexion, plantar flexion, and a neutral position. Imaging included radiography, sonography, and MR imaging. Three observers who were aware of possible joint fluid evaluated the images by consensus and determined the presence or absence of joint effusion.

RESULTS: MR imaging revealed 1 ml of fluid within the anterior recess of the ankle in a neutral position and in plantar flexion and within the posterior recess in dorsiflexion. Sonography revealed 2 ml of fluid within the anterior recess in a neutral position and in plantar flexion. Radiography revealed 5 ml of fluid within the anterior recess in a neutral position.

CONCLUSION: MR imaging, sonography, and lateral radiography, in order of decreasing sensitivity, revealed ankle effusion. The power to reveal with each technique is influenced by the precise position of the ankle.