Simple bone cyst: A discrepancy between magnetic resonance imaging and surgical observations

OBJECTIVE: The purpose of this study was to compare magnetic resonance (MR) imaging and surgical observations of fluid in simple bone cysts. STUDY DESIGN: Findings during MR imaging of 7 simple bone cysts were compared with surgical observations 1 day or 1.8 months (mean) after MR imaging. RESULTS: All MR images showed cavities filled with fluid. In 2 patients operated on the day after the imaging, surgical observations were in accordance with the MR findings. At surgery 1.8 months after the MR examination, 4 cavities were found to be empty and 1 cavity contained only a minor amount of fluid. CONCLUSION: A discrepancy between MR imaging and surgical observations of fluid in simple bone cyst cavities was observed that might be dependent on the time between the observations, indicating that a fairly rapid absorption of fluid might occur or that the amount of fluid in a simple bone cyst can vary for unknown reasons.